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This is to certify that the
thesis entitled

ALTERNATIVE METHODS OF WEED CONTROL FOR
CARROT PRODUCTION

presented by

JUAN JOSE CISNEROS

has been accepted towards fulfillment
of the requirements for the

MS. degree in Horticulture

 

 

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My 33. 1006

Date

 

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2/05 p:/ClRC/Date0ue.indd-p.1

ALTERNATIVE METHODS OF WEED CONTROL FOR CARROT
PRODUCTION

By

Juan Jose Cisneros

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
Department of Horticulture

2006

ABSTRACT
ALTERNATIVE METHODS OF WEED CONTROL FOR CARROT PRODUCTION
By
Juan Jose Cisneros

Experiments were conducted to study alternative methods of weed control in
carrot. Several herbicides were tested in Michigan between 2001 and 2003 for
preemergence and postemergence weed control in carrot. Preemergence clomazone and
ﬂufenacet plus metribuzin (Domain®) were consistently safe on carrot and provided
good weed control during the production season. Carrot stand counts and yield in these
herbicide treatments were similar to linuron treatment in all sites and years. Oxyﬂuorfen
postemergence was safe on carrot and also gave good weed control.

In another experiment, an air-assisted rotary atomizer sprayer was compared to a
conventional boom sprayer. Herbicide application effectiveness did not differ between
the conventional sprayer and the rotary atomizer sprayer. However, this sprayer used a
fourth of the amount of liquid compared to the conventional sprayer, an advantage of
fewer reﬁll trips required.

Flame weeding was studied as an alternative method of weed control. Broadleaf
weeds with unprotected growing points were more susceptible to heat than grass weeds
with protected growing points. Furthermore, weeds at earlier developmental stages were
more susceptible to heat than weeds at older stages. In general, better weed control was

obtained when weeds were ﬂamed at the 0-2 leaf stage.

To my wife Carla and my sons Bartolome and Cristobal for their love and unconditional
support

To F austo and Rosa, my loved parents

iii

ACKNOWLEDGEMENTS

I wish to express my sincere appreciation to my major professor Dr. Bernard
Zandstra for his outstanding guidance during my graduate studies and his open
ﬁ'iendship, and to Drs. Karen Renner, Mathieu Ngouajio, and Gary Van Ee, members of
my committee, for their advice and support.

I wish to thank to the Department of Horticulture and the MSU Horticulture
Teaching and Research Center staff for their help during my research. Many thanks also

to Dr. Joseph Masabni and Michael Particka for their help with the ﬁeld work.

iv

TABLE OF CONTENTS

LIST OF TABLES ............................................................................................................. vi
CHAPTER I ........................................................................................................................ 1
REVIEW OF LITERATURE .................................................. ' ........................................... 1
Introduction ..................................................................................................................... 1
Literature Review ........................................................................................................... 5
Literature Cited ............................................................................................................. 21
CHAPTER II ..................................................................................................................... 25
ALTERNATIVE HERBICIDES FOR WEED CONTROL IN CARROT ...................... 25
Introduction ................................................................................................................... 25
Materials and Methods .................................................................................................. 26
Results and Discussion ................................................................................................. 38
Literature Cited ............................................................................................................. 84
CHAPTER III ................................................................................................................... 87
COMPARISON OF A ROTARY ATOMIZER “PROPTEC” AND CONVENTIONAL
SPRAYER FOR HERBICIDE APPLICATION IN CARROTS. .................................... 87
Introduction ................................................................................................................... 87
Materials and Methods .................................................................................................. 89
CHAPTER IV ................................................................................................................. 100
FLAME WEEDING EFFECTS ON SEVERAL WEED SPECIES ............................... 100
Introduction ................................................................................................................. 100
Material and Methods ................................................................................................. 103
Results and Discussion ............................................................................................... 106
Literature Cited ........................................................................................................... 118
APPENDICES ................................................................................................................ 1 19

LIST OF TABLES
Table 1. Greenhouse preemergence herbicide treatments on carrot in 2001 and 2002 27
Table 2. Greenhouse postemergence herbicide treatments on carrot in 2001 and 2002 .. 28

Table 3. List of herbicide treatments and rates, applied on carrot in Oceana County during

2001 .................................................................................................................................. 3 1
Table 4. List of herbicide treatments and rates applied on carrot in Oceana County during
2002 .................................................................................................................................. 32
Table 5. List of herbicide treatments and rates applied on carrot in Oceana County during
2003 .................................................................................................................................. 33
Table 6. List of herbicide treatments and rates applied on carrot in Newaygo County

during 2001 and 2002 ....................................................................................................... 34
Table 7. List of herbicide treatments and rates applied on carrot in Newaygo County

location during 2003 ......................................................................................................... 35
Table 8. List of herbicide treatments and rates applied on carrot at the Muck Farm during
2003 .................................................................................................................................. 36
Table 9. Field experiments site details ............................................................................. 37

Table 10. Summary of the effect of preemergence herbicides on carrot grown in the
greenhouse. ....................................................................................................................... 40

Table l 1. Effect of preemergence herbicides on carrot stand and fresh weight applied in
the greenhouse on March 2001. ........................................................................................ 41

Table 12. Effect of preemergence herbicides applied in the greenhouse on May 2001, on
carrot stand and fresh weight. ........................................................................................... 42

Table 13. Effect of preemergence herbicides applied in the greenhouse on April 2002, on
carrot stand, injury level, and fresh weight. ...................................................................... 43

Table 14. Effect of preemergence herbicides applied in the greenhouse on March 2003,
on carrot stand, injury level, and fresh weight. ................................................................. 44

Table 15. The effect of postemergence herbicides on carrot grown in the greenhouse —
summary of results. ........................................................................................................... 46

Table 16. Effect of postemergence herbicides applied in the greenhouse on March 2001,
on carrot stand and ﬂesh weight. ...................................................................................... 47

Table 17. Effect of postemergence herbicides applied in the greenhouse on May 2001, on
carrot stand and fresh weight. ........................................................................................... 48

vi

Table 18. Effect of postemergence herbicides applied in the greenhouse on April 2002,

on carrot stand, injury level, and ﬂesh weight. ................................................................. 49
Table 19. Effect of postemergence herbicides applied in the greenhouse on March 2003,
on carrot stand, injury level, and ﬂesh weight. ................................................................. 50
Table 20. The effect of preemergence ﬂumioxazin on carrot stand, injury, and yield 1n the
ﬁeld. .................................................................................................................................. 52
Table 21. The effect of postemergence ﬂumioxazin on carrot stand, 2001 and 2002. ..... 54
Table 22. The effect of postemergence ﬂumioxazin on carrot injury, 2001, 2002, and
2003. ................................................................................................................................. 55
Table 23. The effect of postemergence ﬂumioxazin on carrot yield, 2001, 2002, and
2003. ................................................................................................................................. 56
Table 24. The effect of preemergence ﬂufenacet plus metribuzin on carrot stand, 2001,
2002, and 2003 .................................................................................................................. 59
Table 25. The effect of preemergence ﬂufenacet plus metribuzin on carrot injury, 2001,
2002, and 2003 .................................................................................................................. 60
Table 26. The effect of preemergence ﬂufenacet plus metribuzin on carrot yield, 2001,
2002, and 2003. ................................................................................................................. 61
Table 27. The effect of preemergence clomazone on carrot stand, 2002 and 2003. ........ 63
Table 28. The effect of preemergence clomazone on carrot injury, 2002 and 2003. ....... 64
Table 29. The effect of preemergence clomazone on carrot yield .................................... 65
Table 30. The effect of postemergence oxyﬂuorfen on carrot stand, 2001 and 2002. ..... 67
Table 31. The effect of postemergence oxyﬂuorfen on carrot injury, 2001, 2002, and
2003 .................................................................................................................................. 68
Table 32. The effect of postemergence oxyﬂuorfen on carrot yield, 2001, 2002, and 2003
.......................................................................................................................................... 69
Table 33. The effect of postemergence mesotrione on carrot stand, 200] and 2002 ....... 72
Table 34. The effect of postemergence mesotrione on carrot injury, 2001 , 2002, and
2003. ................................................................................................................................. 73

Table 35. The effect of postemergence mesotrione on carrot yield, 2001, 2002, and 2003.
.......................................................................................................................................... 74

Table 36. The effect of preemergence ﬂufenacet on carrot stand, 2001, 2002, and 2003.76

vii

Table 37. The effect of preemergence ﬂufenacet on carrot injury, 2001, 2002, and 2003.
.......................................................................................................................................... 77

Table 38. The effect of preemergence ﬂufenacet on carrot yield, 2001, 2002, and 2003.78

Table 39. The effect of preemergence metribuzin on carrot stand, injury, and yield. ...... 79
Table 40. The effect of preemergence s-metolachlor, pendimethalin, and sulfentrazone

on carrot stand, injury, and yield. ..................................................................................... 80
Table 41. The effect of preemergence mesotrione on carrot stand, injury, and yield. ..... 81
Table 42. List of treatments applied at the MSU Muck Farm during 2001 ...................... 91
Table 43. Analysis of variance of carrot injury, Proptec experiment ............................... 93
Table 44. Analysis of variance of yellow nutsedge control, Proptec experiment ............ 94
Table 45. Analysis of variance of carrot ﬂesh weight, Proptec experiment ..................... 95

Table 46. ADV main effect of linuron rate, adjuvant use, and sprayer type factors
independently of each other on carrot injury, yield, and yellow nutsedge control, Proptec
experiment. ....................................................................................................................... 96

Table 47. ADV means effect of linuron rate, adjuvant use, and sprayer type factors on
carrot injury, yield, and yellow nutsedge control ............................................................ 97

Table 48. Weeds species studied. .................................................................................. 104

Table 49. Results ﬂom ﬂaming bamyardgrass at 0-2 and 2-4 leaves. Five hundred seeds
were planted per ﬂat ....................................................................................................... 108

Table 50. Results ﬂom ﬂaming green foxtail at 0-2 and 2-4 leaves. Five hundred seeds
were planted per ﬂat ....................................................................................................... 110

Table 51. Results ﬂom ﬂaming large crabgrass at 0-2 and 2-4 leaves. Five hundred
seeds were planted per ﬂat .............................................................................................. 1 12

Table 52. Results ﬂom ﬂaming redroot pigweed at 0-2 and 2-4 leaves. Five hundred
seeds were planted per ﬂat .............................................................................................. 114

Table 53. Results ﬂom ﬂaming common ragweed at 0-2 and 2-4 leaves. Five hundred
seeds were planted per ﬂat .............................................................................................. 115

Table 54. Results ﬂom ﬂaming common lambsquarters at 0-2 and 2-4 leaves. Five
hundred seeds were planted per ﬂat ................................................................................ 1 16

viii

CHAPTER I

REVIEW OF LITERATURE

IntroduCtion

Carrot is an important vegetable crop in several states in the US, including
California, Colorado, Florida, and Michigan. In 2002, the total carrot harvested area in
the US was over 43,000 ha. Michigan ranks ﬁfth nationally in carrot production with a
total harvested area of approximately 2,500 ha (U .S. Department of Agriculture, 2002).
The main carrot producing counties in Michigan are Muskegon, Montcalm, and Oceana
counties on mineral soils, and Newaygo and Lapeer counties on muck soils.

In general carrot production relies heavily on pesticides to increase quality and
productivity. In particular, herbicides constitute about 60% of the total tonnage of
pesticides applied annually on conventional vegetable production farms (Gianessi and
Marcelli, 2000). This substantial use of herbicides may cause several problems such as
chemical carryover, residues in the crop, soil, and groundwater, and weed resistance.
Herbicide usage is essential for carrot production due to its low competitive capacity with
weeds. Carrot emerges slowly preventing carrot ﬂom competing efﬁciently against
weeds during the ﬁrst six weeks of growth. In addition to competition for nutrients,
water, and light and the consequent carrot yield reduction, weeds may act as host to
insects and pathogens and may interfere with harvesting operations (US. Department of
Agriculture, 1999; Bell et al., 2000a; Stall, 2003). Bell et al. (2000a) reported an 85%

reduction in carrot yield when no weed control program was applied.

In Michigan, three herbicides are labeled for preemergence use in carrots:
triﬂuralin, metribuzin, and linuron. Linuron is the most widely used herbicide and has
the widest spectrum of weed control (Bellinder et al., 1997; Bell et al., 2000a; Michigan
State University, 2000; Stall, 2003; Zandstra, 2004). Linuron is the primary herbicide on
90% of Michigan carrot acreage (Crop Life Foundation, 1997). Linuron is a safe,
efﬁcient, and cost effective herbicide for carrot weed control and gives the highest rate of
return ﬂom incremental investment in weed control (Bell et al., 2000a; Michigan State
University, 2000). Nevertheless, linuron is an herbicide that has been in use for several
decades. Linuron was ﬁrst registered in the US. in 1966. From 1984 to 1988 linuron
was under special review because it exceeded the oncogenicity risk criteria. At present,
linuron and all other herbicides labeled for carrots face an uncertain ﬁrture as a result of
the Food Quality Protection Act (FQPA) of 1996, that requires the Environmental
Protection Agency (EPA) to reassess all pesticide tolerances by 2006 (Bell eta1., 2000b).
Therefore, there is a future risk of use restriction, label elimination, or manufacturer
voluntary withdrawal of the herbicides labeled for carrots.

The FQPA promotes the development and use of new environmentally friendly
pesticides. In the past years many new herbicides have been introduced for use in major
crops (Bell et al., 2000b; Haar et al., 2002). Most of these new herbicides are active at
very low rates compared to their predecessors, which should result in lower residues in
the crop, soil, and groundwater (Putnam, 1990; Haar et al., 2002; Ogbuchiekwe et al.,
2004). Unfortunately, there is little economic incentive for chemical companies neither
to register new herbicides for minor crops, nor to invest in research to develop herbicides

for minor crops (Bell et al., 2000b; Haar et al., 2002).

Dependence on a few herbicides for many years may result in the development of
herbicide resistant weeds. Masabni and Zandstra (1999) identiﬁed linuron-resistant
common purslane (Portulaca oleracea L) in Michigan carrots ﬁelds. Beuret (1989)
reported the discovery of biotypes of common groundsel (Senecio vulgaris L) resistant to
linuron in carrots in Switzerland. The dependence on linuron for weed control in carrots
may lead to the development of additional weed resistance. In addition, linuron requires
high rates compared to new low-rate herbicides that in many cases are active at rates of
grams per hectare. Herbicides applied at higher rates are more likely to cause problems
such as chemical carryover and chemical residues in the crop, soil, and groundwater than
new low-rate herbicides (Haar et al., 2002; Ogbuchiekwe et al., 2004). Some Michigan
carrot growers produce carrot for the baby food industry, which is greatly concerned with
chemical residues in raw product. As a result they demand lower inputs of pesticides in
their carrot production. These growers are facing a major challenge to produce carrots
with lower residues without the availability of alternative herbicides (Michigan State
University, 2000).

A common cultural practice in Michigan carrot production to prevent erosion and
seedling damage ﬂom wind is planting of a small grain nurse crop, usually rye (Secale
cereale L.) or barley (Hordeum vulgare L.). When the cover crop reaches four inches
high it is killed with an herbicide to prevent competition with the carrot crop (US.
Department of Agriculture, 1999; Michigan State University, 2000). Linuron applied

preemergence has limited activity on annual grasses (Kuratle and Rahn, 1968; Michigan

State University, 2000), so in most situations it does not have an adverse effect on the
small grain nurse crop.

There are limited choices for alternative weed control programs in carrots.
Below-labeled rate may be an alternative for reducing total herbicide usage, reducing off-
‘target crop damage, and increasing proﬁt margins (Putnam, 1990; Zhang et al., 2000).
Below-labeled rates have been studied by Putnam (1990), Bellinder et al. (1997), Zhang
et a1. (2000), and Ogbuchiekwe et al. (2004). A single low-rate application (0.14 kg
ai/ha) of linuron postemergence did not control redroot pi gweed (Amaranthus retroﬂexus
L.) or common lambsquarters (Chenopodium album L.), and reduced carrot yield.
However, two low-rate postemergence applications (0.14 kg ai/ha) of linuron
signiﬁcantly improved weed control and there was no yield reduction. Similar results
were obtained with low-rate metribuzin applications (Bellinder et al., 1997). Few studies
have been reported on selectivity of new low-rate herbicides in carrot.

Physical weed control methods have been developed in other vegetable crops,
including ﬂaming and mechanical weed control. The use of mechanical methods for
weed control and cover crop removal in carrot production is limited. No mechanical weed
control is recommended before carrot has reached at least 15 cm to avoid root injury.
Moreover, carrots are grown at very high plant densities preventing effective cultivation
to control weeds without damaging the crop (Bell et al., 2000).

The objectives of this research were to: evaluate the selectivity of several new
herbicides developed for major agronomics crops in carrots; evaluate level of weed
control of the same herbicides at rates that were safe for carrots; and gain a better

understanding of ﬂame weeding in grass and broadleaf weed control.

Literature Review

Chemical Weed Control in Carrot Crop

Preemergence herbicides labeled for carrot crops in Michigan

Triﬂuralin was ﬁrst registered in the US in 1963. It is incorporated preemergence
to control annual grasses and broadleaf weeds. Triﬂuralin belongs to the dinitroaniline
chemical family. It is absorbed by plants through developing roots and impedes mitosis
and cell elongation. Currently, triﬂuralin is classiﬁed as a Group C carcinogen by the
Environmental Protection Agency (EPA). EPA deﬁnes C carcinogen as possible human
carcinogen for which there is limited animal evidence (United States Environmental
Protection Agency, 1996; Bell et al., 2000a; Michigan State University, 2000).

Triﬂuralin is used on limited carrot acreage in Michigan. It is effective on mineral
soil, for control of annual grasses and some broadleaves. It does not control Composite
weeds, mustards, or nightshades. It is very safe on carrots, but it kills the small grain

cover crops used in carrot production (Michigan State University, 2000; Zandstra, 2004).

Preemergence and postemergence herbicides labeled for carrot crops in Michigan
Linuron was ﬁrst registered in the US in 1966. In the 19803, linuron underwent a
special review because of potential oncogenicity. However, there was no strong evidence
that it causes cancer in humans. EPA decided to classify linuron as an unquantiﬁable
Group C carcinogen (United States Environmental Protection Agency, 1995). Linuron

belongs to the substituted urea chemical family and its mode of action is inhibiting

photosynthesis in photosystem II. This herbicide controls a broad spectrum of weeds on
organic and mineral soils and is effective preemergence and postemergence.

In Michigan, linuron is the most widely used herbicide for carrot production.
Moreover, carrot production without linuron would not be proﬁtable because there is no
current substitute for postemergence broadleaf control (Michigan State University, 2000).
Preemergence and postemergence applications of linuron are safe on carrots. Linuron
appears to be safe early in the season when carrot is in the 1-2 true leaf stage (Kuratle and
Rahn, 1968). However, the label does not allow linuron application until the carrot crop
reaches 7.6 cm in height, which limits the effectiveness of postemergence weed control
(Bellinder et al., 1997; Zandstra, 2004). Crop injury and yield reduction have occurred
when linuron was applied postemergence with temperatures above 30 degree Celsius
(Kuratle and Rahn, 1968). Linuron is very effective against most broadleaf and annual
grass weeds. Fortunately, it does not kill the small grain cover crop needed to protect the
soil and carrot ﬂom wind erosion and damage respectively (Michigan State University,
2000). Linuron controls redroot pi gweed and common lambsquarters, both very common
annual broadleaf weeds in Michigan carrot ﬁelds. However, at reduced rates, the weed
control is variable. Moreover, a single postemergence application of linuron may result in
poor weed control and reduced carrot yield (Bellinder et al., 1997). Temperature during
postemergence treatment does not affect broadleaf weed control. However, high
temperature either before or after postemergence linuron application reduces its
effectiveness against annual grasses (Kuratle and Rahn, 1968).

Intensive use of linuron in carrots may result in linuron-resistant weeds. Linuron-

resistant common purslane has been found in Michigan carrot ﬁelds (Masabni and

Zandstra, 1999). Beuret (1989) reported linuron-resistant biotypes of common groundsel

in carrot crops in Switzerland.

Postemergence herbicides labeled for carrot crops in Michigan

Metribuzin was ﬁrst registered in the US in 1973. In 1991 and 1995, EPA
required supplementary information related to metribuzin chemistry, environmental fate
and groundwater, and ecological effect (United States Environmental Protection Agency,
1998)

In Michigan, metribuzin is used to substitute for one postemergence linuron
application (Bell et al., 2000b) when the carrot has reached at least 5-6 leaves.
Metribuzin is registered for postemergence application in carrot; however, Jensen et al.
(2004) found that carrot tolerance to metribuzin preemergence application was similar to
preemergence linuron. Metribuzin does not have as wide a spectrum of weed control as
linuron; under certain condition it can injure carrots, and it can only be applied one time
per season (Zandstra, 2004). Therefore this herbicide cannot be used as a primary
solution for a weed control program in carrot production. Jensen et al. (2004) found
injury levels ﬂom 2 to 42% in carrots when metribuzin was applied to carrots at the 4-5
leaf stage. Carrot injury increased as temperature increased. Injury only occurred to the

leaves sprayed, but not to the new leaves.

Thermal Weed Control

Cultivation is the most extensively used mechanical weed control method.
However, cultivation stimulates new weed ﬂushes (Rasmussen, 2003). In addition soil
disturbance decreases water retention in the soil, which limits the amount of water
available for the crop. Other disadvantages of cultivation are that it cannot control intra-
row weeds, and cultivation may injure crop roots (Heiniger, 1999).

Thermal weed control may be an alternative to cultivation for physical weed
control. There are several techniques of thermal weed control such us ﬂame weeding,
inﬂared radiation, steam and hot water, electric, microwaves, etc. Flame weeding with
liqueﬁed petroleum gas (LPG) burners is the oldest and most commonly used technique
for thermal weed control (Rahkonen etal., 2003).

During the 1950S and early 19603 ﬂame weeding with propane burners was very
common in US agriculture. By the late 1960’s improvement in herbicide efﬁciency and
lower cost pushed ﬂame weeding into obsolescence (Heiniger, 1999; Diver, 2002). In
recent years there has been increased interest in thermal weeding as an alternative or
complement to chemical weed control, especially where problems with herbicide-
resistant weeds have occurred (Moj iis, 2002). Thermal weed control should help prevent
development of herbicide resistant weeds, since no weed is resistant to temperatures
above the boiling point of water (Heiniger, 1999).

Thermal weed control has several advantages. In organic agricultural production
and in crops where herbicides are not available, thermal weed control may decrease labor

required for hand weeding. In addition, thermal weed control leaves no chemical

residues that may contaminate soil and water. Thermal weed control also is compatible
with no-tillage production techniques. A major limitation of thermal weed control is the
non-selectivity, limiting its usage to crop preemergence and to a limited number of heat
resistant crops postemergence. In general, thermal methods have a relative low weed-

control capacity with a high consumption of fossil fuels (Ascard, 1998).

Weed Susceptibility to Thermal Treatment

The thermal weed control technique consists of exposing weed foliage to high
temperatures for a relatively short period of time. This heat exposure denaturizes plant
proteins, which results in loss of cell function, causes intracellular water expansion, cell
membrane rupture, and ﬁnally desiccates and kills the weeds, normally within 2 to 3 days
(Heiniger, 1999; Campbell, 2004; Rahkonen, 2003; Diver, 2002). It is not necessary to
burn the weeds to cause death. One technique to verify the sufﬁciency of the ﬂaming
treatment is applying pressure to the leaves between thumbs and ﬁngers. An imprint in
the foliage indicates cell membrane rupture (Campbell, 2004; Diver, 2002).

The susceptibility of the weeds to thermal weed control is determined by several
factors. The developmental stage of the weed is probably the most important factor;
seedlings with the shoot apex exposed are more susceptible to ﬂame weeding than older
stages where the shoot apex might be protected by surroundings leaves, or where axillary
buds may have developed. In addition, older stages have larger surface and larger
biomass, which requires a higher ﬂaming dose to heat. Ascard (1994) found a linear
relationship between a weed’s fresh weight and the effective propane dose for 95% weed

reduction. It required doses above 40 kg ha'1 to achieve 95% control of weeds with 0 to 2

true-leaves, whereas it required up to 70 kg ha'1 to achieve the same control level in
weeds with 2 to 4 true-leaves. In general, broadleaves are more susceptible to heat than
grasses because grasses develop a sheath that in many cases protects the growing point.
Weeds with growing points below the soil surface might have the capacity to regrow aﬁer
ﬂaming treatment, because ﬂaming has a superﬁcial effect. Finally, annual weeds are
more susceptible to ﬂame weeding than biennial and perennials (Diver, 2002; Monis,

2002; Ascard, 1995a, 1998).

Measuring temperature

Two methods of plant temperature measurement are used in thermal weed control.
One method is by contact sensors, usually using small thermocouples inserted in the leaf.
The other method is by inﬂared meters. Rahkonen (2003) concluded that it is possible to
obtain accurate measurements with either method. Quite the opposite, Ascard (1995b)
stated that accurate measurement of leaf temperatures during ﬂaming is very difﬁcult as
the temperature changes constantly. If a thermocouple is inserted into a leaf, it will itself
act as a heat sink and the type and size of the thermocouple will inﬂuence the results. An
inﬂared thermometer can be used as a non-contact temperature measurement method.
The main advantage of this method is the non-inﬂuence on the target temperature, but the
main downside of this technique is the slow response time (Ascard, 1995b).

Thermal weed control usually does not involve burning the weeds; this being the
case, temperature in the leaf does not exceed 100 degree Celsius as a result of moisture
vaporization ﬂom the leaf surface. This moisture vaporization creates a cooling layer

which prevents temperatures higher than 100 degree Celsius (Ascard, 1995b).

10

Ascard (1999) recommends measuring temperature in the ﬂame, or vicinity of the
plant, or in an environment without plants. However, Ascard advises that the
temperatures recorded by the thermocouples are not temperatures of the air nor of the leaf
but of the thermocouple itself. Moreover, in a non-stationary situation the temperature
registered will depend on the thickness of the thermocouple. Thus a maximum
temperature of 700 degree Celsius recorded by a 0.25 mm thermocouple corresponds to

900 degree Celsius in a 0.13 mm thermocouple.

Flame Weeding

Flame weeding is by far the most common thermal weed control method in
agriculture (Ascard, 1995b). This technique uses liqueﬁed petroleum gas (LPG) burners
to generate combustion temperatures of up to 1900 degree Celsius, raising the
temperature of the exposed leaves very rapidly, causing cell membrane rupture and later
desiccation and death of the weed. Aﬁer its almost complete disappearance in the 19703,
ﬂame weeding is starting to regain interest, mainly in Europe for non-selective weed
control in organic production (Ascard, 1995b).

As in any other weed control technique ﬂame weeding has advantages and
disadvantages. The main advantages of ﬂame weeding are the lack of chemical residues
remaining in the crop, soil, or water; the no carry-over effect on the next season, the wide
spectrum of weeds controlled, and the non-possibility to develop weed resistance to
ﬂaming (Ascard, 1995b; Heiniger, 1999). The main disadvantages of ﬂame weeding are
the lack of residual effect, which requires repeated applications, the lack of selectivity for

crop safety, low speed of application, human safety issues, and the high total cost

11

(Ascard, 1995b). The soil surface condition also may be a limitation for effective ﬂame
weeding. A rough surface with many soil clods may cause upward ﬂame deﬂections that
reduce the heat effects close to the surface. In addition, soil clods also could act as shields
for small weed seedlings (Ascard, 1999).

The major factor inﬂuencing ﬂame weeding efﬁcacy is the developmental stage
of the weeds at the time of ﬂaming, that determines the weed sensitivity to the treatment.
The stage of growth of the weeds establishes the kind and degree of protective layers, the
ligniﬁcation level, and the location of growth points. For most weed species, ﬂaming will
be most effective when weeds are in the early growth stage (Ascard, 1995a; Campbell,
2004).

In addition to the grth stage of the weeds, the efﬁcacy of the ﬂaming treatment
is determined by the combinations of two additional factors, the amount of heat
transferred ﬂom the burner and the time of exposure of the weeds to the heat (Heiniger,
1999; Ascard, 1998). The amount of heat transferred by the ﬂarner to the weeds is
determined by the number of burners for a giving working width, the nozzle size, and the
gas pressure. Each burner type has its own optimum fuel pressure, and there is a narrow
interval for changing the fuel pressure for a given burner type. The exposure time is
determined by the tractor speed. Ascard (1998), found a strong positive correlation
(r2=99) between the combination of temperature-exposure (temperature sum) and the
weeds killed. The correlation was slightly lower when temperature alone was correlated
with weeds killed or exposure time alone was correlated with weeds killed. These two
factors combined are commonly cited in the literature as propane consumption per

hectare (Mojzis, 2002) or propane consumption per unit working width (Ascard, 1998).

12

This propane consumption is determined by gas pressure and the speed of the tractor.
Higher propane consumption is obtained by higher pressure and lower tractor speed. The
relationship between propane consumption per hectare and weed control is direct; the
higher the propane consumption, the better the weed control. Factors that affect ﬂame
weeding performance are: burner type, fuel pressure, burner height, treatment speed, and
wind (Ascard, 1999).

The relationship of these factors with the efﬁcacy of the ﬂaming treatment is
simple. Gas pressure has a direct relationship with heat produced; the higher the
pressure, the more heat is produced. For tractor speed there is an inverse relationship; the
higher the speed, the lower the heat time exposure. For burner type, there is more
complexity because there are different models available in the market. In other words,
we can have higher tractor speed by increasing the burner power of the ﬂamer (Ascard,
1995b, 1997). In an experiment combining ﬁrel input and ground speed for weed control,
Ascard (1997) found that for a covered ﬂamer with fuel consumption of 34 kg h'1 per
meter working width at a ground speed of 7.9 km h'l, he was able to achieve 95% weed
control. On the other hand, in the same study and for achieving the same level of weed
control but with a fuel consumption of 12 kg h", it required an effective ground speed of

2.6 km h".

Burner Type
Burners are typically classiﬁed by the shape of the burner and ﬂame and the
presence or absence of a vapor chamber (Ascard, 1995b). The most common burner

types are the ﬂat burner and the round burner. The ﬂat burner, also known as the ﬂat

13

vapor burner, produces a wide, ﬂat flame with temperatures of about 1300 degree
Celsius. It is important to mention that the width of the ﬂame can vary depending on the
jet nozzle. Round burners produce long and narrow ﬂames with temperatures of about
1400 degree Celsius. For ﬂame weeding, ﬂat burners are more common, because of their
wide coverage (Campbell, 2004). The presence of a vapor chamber indicates that the
burner is a liquid-phase type; on the other hand the absence of a vapor chamber would
indicate a gas-phase burner. According to Ascard (1995b) there are no consistent

differences between burner types for weed control.

Burner angles

The burner angle has considerable inﬂuence on ﬂame weeding performance. The
burner angle determines how the ﬂame reaches the weed and how long the high
temperature will last. In open ﬂamers, the burner angle is more critical than in covered
ﬂamers because direction of the ﬂame has to be more accurate.

In selective ﬂaming with open high pressure ﬂamers it is generally recommended
to use burner angles of 30 to 45 degrees to the ground. In this technique the ﬂames aim
at the base of the crop, crossing beneath the canopy and avoiding direct contact with the
crop foliage (Diver, 2002; Heiniger, 1999). However, these angles are not necessarily
appropriate in other ﬂaming situations, such as with less powerful burners or non-
selective ﬂame weeding. There are no conclusive studies of the appropriate burner angle

for the different types of ﬂamers and ﬂaming techniques.

Open and Covered Flamers

l4

According to Ascard (1995b), there are basically two different ﬂame weeder
designs, the open burner ﬂamer that is usually used in heat-resistant crops such us cotton,
sugar cane, and corn; and the covered ﬂamer that concentrates the ﬂames under a shield
or insulated cover, commonly used in intra-row treatment in heat-sensitive crops.

Covered ﬂamers are considered more efﬁcient than open ﬂamers, as well as being
operationally safer. This difference in efﬁciency is more obvious in bigger weeds or
more heat-tolerant weeds. Bertram (1991, 1992), in his thermodynamic model, proposes
that the actual heat transferred to the weeds with an open ﬂamer at a fuel consumption of
50 kg ha‘1 is only 15% of the total combustion heat. At the same fuel consumption for a
covered ﬂamer, the heat transferred to the weeds is 30%. Moreover, the heat transferred
to weeds could be increased to 60% of the total combustion heat by optimizing the cover
design (Ascard, 1995b).

Ascard (1995) demonstrated that covered ﬂamers were more efﬁcient than open
ﬂamers. On average, open ﬂamers required 40% more fuel than covered ﬂamers to
achieve the same level of weed control. These differences varied depending on the
developmental stage of the plants. In small, heat-sensitive plants, the difference between
open and covered ﬂamers was minor, whereas in larger plants the difference was more
obvious.

In a study comparing ﬂaming versus cultivation for weed control in popcorn and
soybean, Heiniger (1999) reported that ﬂaming treatment showed consistently better
weed control than cultivation. However, crop yields for both popcorn and soybean were
not signiﬁcantly different between the methods. From a cost point of view, fuel cost of

ﬂame weeding is similar to the cost of herbicides. However, the total cost of ﬂame

15

weeding is much higher than herbicide weed control due to the necessity of

supplementary hand weeding (Ascard, 1995).

Preemergence Flame Weeding

Preemergence ﬂaming is based on the presumption that the ﬁrst ﬂush of weeds is
the largest group to germinate during the season. If there is no soil disturbance after
initial tillage, new weed emergence will be reduced. If ﬂame weeding is applied aﬂer
tillage and just before crop emergence, most weeds will be killed early in the season.

For fast growing crops, preemergence ﬂame weeding would create favorable
conditions for the crop and in many cases allow the formation of full canopy which
impedes later weed emergence. Later ﬂushes of weeds, even though in lower quantities,
may cause serious competition for slow growing crops.

Diver (2002) refers to two distinct techniques to use preemergence ﬂame
weeding, one being the stale seedbed technique and the other the peak emergence

technique.

Stale seedbed technique

The stale seedbed technique consists of delaying planting after seedbed
preparation. Flame is applied to a ﬁeld two to three weeks after tillage, when the ﬁrst
ﬂushes of weeds have emerged (Caldwell and Mohler, 2001; Diver, 2002; Rasmussen,
2003). The basic principle is to delay sowing after tillage, kill the early germinated
weeds and avoid later soil disturbance that promotes germination of weeds. The crop

then is sowed into a weed-ﬂee ﬁeld. Variations on this technique could be irrigating

l6

before ﬂaming to induce more weed germination and punch planting as proposed by
Rasmussen (2003) to minimize soil disturbance.

Punch planting is a technique of sowing used in organically grown crops to
reduce weeds within rows. A hole is punchedin the soil and the seeds are dropped into it
without seedbed preparation and soil disturbance beyond the hole. Rasmussen (2003), in
an experiment combining stale seedbed technique, punch planting, and ﬂame weeding,
found that this combined treatment showed a 30% intra-row weed reduction compared
with normal planting with ﬂame weeding.

The efﬁcacy of the stale seedbed technique is inﬂuenced by the growth rate of the
crop and its critical weed-ﬂee period. The critical weed-ﬂee period is the minimum
amount of time a crop requires to be weed-free to avoid yield reductions or lower quality.
In most cases, this critical weed-free period is during the ﬁrst quarter or third of the
growing period, usually for four to ﬁve weeks. Weeds emerging later in the season have
little or no impact on yield of most crops (Ross & Lembi, 1985; Caldwell and Mohler,

2001).

Peak Emergence Technique

The peak-emergence ﬂaming technique is very similar to the stale seedbed
technique; the main difference being that instead of having a delayed sowing, in the peak
emergence technique the sowing is done right aﬂer seedbed preparation. The ﬂame
treatment is applied just before crop seedlings emerge, which kills the ﬁrst ﬂushes of

seedling weeds. This ﬁrst ﬂush is the most abundant of the season, especially if there are

17

no later soil disturbances. However, this technique is only applicable to slow-
germinating crops such us carrots and parsley.

In general terms, preemergence ﬂame weeding is not sufﬁcient to avoid yield
reduction due to weeds. It could work very well for the establishment of the crop but
later in the season some form of weed control is required. Flame weeding after crop

emergence is known as postemergence ﬂame weeding.

Postemergence Flame Weeding

This technique consists of controlling weeds by ﬂaming after the crop has
emerged. Timing of application is important to avoid crop damage (Campbell, 2004).
For heat-resistant crops such as cotton, corn, and sugarcane, ﬂame weeding can be
applied directly to the bottom of the plant at some growth stages. This technique, called
selective ﬂaming, controls intra-row weeds (Diver, 2002). For heat-sensitive crops,
postemergence ﬂaming can be applied using a covered ﬂamer to protect the crop ﬂom the
intense heat (Ascard, 1995). This technique, also known as parallel ﬂaming, controls the

weeds between the rows.

Cross Flaming

In cross ﬂaming, also known as selective ﬂaming, the burners are directed down
in a 45 degree angle towards both sides of the crop row in an alternate pattern. The
ﬂames aim at the base of the crop, crossing beneath the canopy and avoiding direct
contact with the crop foliage (Diver, 2002; Heiniger, 1999). Cross ﬂaming targets the

small weeds growing in the rows. For cross ﬂaming to be effective, the soil surface must

18

be relatively smooth; a rough surface causes ﬂame deﬂection upwards, which may injure

the crop.

Parallel Flaming

This technique used in heat-sensitive crops and in early growth stages of heat
resistant crops, aims at the weeds growing between rows and close to the rows. In this
method, burners are set parallel to the direction of the crop row or a ﬂamer shield is

employed to protect the crop (Diver, 2002).

Split vs. Single Application

A split application could be used in any of the techniques described above. A
split application is partitioning of the full ﬂaming dose in two half doses applied in
subsequent passes separated in time. Ascard (1995) reported no difference between split
applications with two half dose treatments one week apart and a single late ﬂame
treatment at the same total fuel dose. Despite these results there are some situations
where split applications can be advantageous. For example, in crops with long
germination periods, it may be possible to kill the early ﬁrst ﬂush of weeds before they
get too big and more heat-resistant; and then the second application could be applied just
before crop emergence. It may also be favorable to use split applications in selective

ﬂaming to reduce crop injury.

Infrared Weed Control

19

The inﬂared weeder is a variation to the covered ﬂamer design characterized by
not having a visible ﬂame. Inﬂared weeders use propane burners that heat a ceramic or
steel surface to a red brightness at temperatures around 900 degree Celsius that then
irradiates heat towards the weeds (Diver, 2002; Campbell, 2004). Safety is the main
advantage of using inﬂared weeders over ﬂaming due to the lack of an open ﬂame.
Disadvantages of inﬂared weed control are the poor capacity to penetrate dense canopies,
the slower speed required for application, and the high cost of the equipment (Ascard,
1998).

Ascard (1998) reported substantially higher temperatures reached under a ﬂamer
than under an inﬂared weeder when temperatures were measured 1 cm above the ground.
However, the temperature under the ﬂamer was only slightly higher at 3.5 cm above
ground. In the same study, Ascard found that inﬂared weeders and ﬂamers require the
same dose of propane (60 kg per ha) to obtain a 95% weed reduction at a 0 to 2-leaf
stage; in other words, both thermal weeders had comparable effects on weeds at the same
propane doses. Since ﬂamers have higher consumption capacity than inﬂared weeders,

the effective speed of application is higher in ﬂame weeders.

2O

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acetochlor, and atrazine for weed management in corn (Zea mays). Weed
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density. Weed Research 34: 337-3 85.

Ascard, J. 1995a. Effects of ﬂame weeding on weed species at different developmental
stages. Weed Research 35: 397-411.

Ascard, J. 1995b. Thermal weed control by ﬂaming: biological and technical aspects.
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Ascard, J. 1999. F lame weeding: effects of burner angle on weed control and temperature
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1089-1091.

Bell, C. E., S. A. Fennimore, M. E. McGiffen, Jr., W. T. Lanini, D. W. Monks, J. B.
Masiunas, A. R. Bonanno, B. H. Zandstra, K. Umeda, W. M. Stall, R. R.
Bellinder, R. D. William, and R. B. McReynolds. 2000b. My view. Weed Science
48:1.

Bellinder, R. R., J. J. Kirkwyland, and R. W. Wallace. 1997. Carrot (Daucus carota) and
weed response to linuron and metribuzin applied at different crop stages. Weed
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Beuret, E. 1989. A new problem of herbicide resistance: Senecio vulgaris L. in carrot
crops treated with linuron. Revue-Suisse—de-Viticulture,-d'Arboriculture-et-
d'Horticulture 21 (6): 349-352.

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Brown D. and J. Masiunas. 2002. Evaluation of herbicides for pumpkin (C ucurbita spp.).
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Caldwell, B. and C. L. Mohler. 2001. Stale seedbed practices for vegetable production.
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Campbell, R. 2004. Flame weeding. Organic Agriculture Centre of Canada.
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Cavero J ., J. Aibar, M. Gutierrez, S. Fernandez-Cavada, J. M. Sopeﬁa, A. Pardo, M. L.
Suso, and C. Zaragoza. 2001. Tolerance of direct-seeded paprika pepper
(Capsicum annuum) to clomazone applied preemergence. Weed Technology
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Crop Life Foundation. 1997. National pesticide use database.
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Diehl, H. J. and W. Benz. 1998. FOE 5043 (ﬂufenacet) and mixing partners for use in
maize, cereals, and potatoes in Germany. Pﬂanzenschutz-Nachrichten Bayer 51
(2) 129-138.

Diver, S. 2002. Flame weeding for vegetable crops. ATTRA bulletin.
http://attra.ncat.org/attra-pub/PDF/ﬂameweedvegpdf.

Ghosheh, H. Z. 2004. Single herbicide treatments for control of broadleaved weeds in
onion (Allium cepa). Crop Protection 23: 539—542.

Gianessi, L. P. and M. B. Marcelli. 2000. Pesticide use in US. crop production: 1997.
National Center for Food and Agricultural Policy.
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Grichar W. J ., B. A. Besler, K. D. Brewer and D. T. Palrang. 2003. Flufenacet and
metribuzin combinations for weed control and corn (Zea mays) tolerance. Weed
Technology 17:346—351.

Haar, M. J ., S. A. Fennimore, M. E. McGiffen, W. T. Lanini, and C. E. Bell. 2002.
Evaluation of preemergence herbicides in vegetable crops. HortTechnology 12
(1): 95-99.

Hansson, D. and J. Ascard. 2002. Inﬂuence of developmental stage and time of
assessment on hot water weed control. Weed Research 42: 307—3 16.

Heiniger, R. W. 1999. Controlling weeds in organic crops with ﬂame weeders. Organic

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Farming Research Foundation, Information Bulletin No. 6: 17-19.

Jensen, K. I. N., D. J. Doohan, and E. G. Specht. 2004. Response of processing carrot to
metribuzin on mineral soils in Nova Scotia. Canadian Journal of Plant Science 84:
669—676.

Johnson B. C. and B. G. Young. 2002. Inﬂuence of temperature and relative humidity on
the foliar activity of mesotrione. Weed Science 50:157—1 61.

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application rate and timing of mesotrione on corn (Zea mays) response and weed
control. Weed Technology 16:414—420.

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with Daucus carota and Chenopodium album. Ecological Research 15: 293-306.

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and R. A. Wichert. 2001. Mesotrione: a new selective herbicide for use in maize.
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Engineering. 48 (3): 94—97.

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23

Peachey, R. E. and C. Mallory-Smith. Tolerance of processed vegetables to herbicides.
Oregon State University. http://oregonLu1te.edu/dept/hort/weedrpt/screenZ.htm

Putnam, A. R. 1990. Vegetable weed control with minimal herbicide input. HortScience
25 (2): 155-159.

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73 8-F -96-006. http://wwwepagov/oppsrrd 1 /REDs/factsheets/01 81 factfpdf

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Michigan State University. Extension Bulletin E 433.

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at below-labeled rates. Weed Technology 14: 106-115.

24

CHAPTER II

ALTERNATIVE HERBICIDES FOR WEED CONTROL IN CARROT

Introduction

Good weed control is essential in carrot production. Carrots emerge and grow
slowly during the ﬁrst six weeks of growth, which limits their ability to compete against
weeds. Weeds also may act as hosts for insects and diseases and may interfere with
harvesting operations (Bell et al., 2000a; Stall, 2003; US. Department of Agriculture,
1999). Weeds may reduce carrot yield up to 85% (Bell et al., 2000a).

Only two herbicides are registered for preemergence use in carrot on mineral soil
in the United States: linuron and triﬂuralin. S-metolachlor is registered for use on soils
with more than 20% organic matter. Linuron is the most widely used herbicide for carrot
and has the broadest weed control spectrum (Bell et al., 2000a; Bellinder et al., 1997;
Michigan State University, 2000; Stall, 2003; Zandstra, 2004). Ninety percent of carrot
acreage in Michigan is treated with linuron (Crop Life Foundation, 1997). Linuron is a
safe, efficient, and cost effective herbicide for weed control in carrot with no alternative
with the same characteristics (Bell et al., 2000a; Michigan State University, 2000).
Nevertheless, linuron has been used for several decades; linuron was ﬁrst registered as a
pesticide in the US. in 1966. From 1984 through 1988 linuron was under special review
because it exceeded the oncogenicity risk criteria. At present, linuron and all other
labeled herbicides for carrots face an uncertain future as a result of the Food Quality

Protection Act (FQPA) of 1996, that requires the Environmental Protection Agency

25

(EPA) to reassess all pesticide tolerances by 2006 (Bell et al., 2000b). Therefore, there is
a future risk of use restriction, label elimination, or voluntary withdrawal of the
herbicides labeled for carrot by manufacturers. The continued use of linuron for weed
control in carrots may lead to the development of herbicide-resistant weeds. Masabni and
Zandstra (1999) reported linuron-resistant Portulaca oleracea in carrot ﬁelds that had
been treated with linuron for over 20 years. Beuret (1989) reported biotypes of Senecio
vulgaris with resistance to linuron in carrot crops in Switzerland. Another concern
regarding linuron is the tendency of baby food processors to require reduced chemical
use in carrot suppliers. Growers producing carrot for baby food face a major challenge to
produce carrots without the availability of alternative herbicides (Michigan State
University, 2000).

Few studies have been conducted to test selectivity of new herbicides in carrot.
The objective of this study was to evaluate several new and older herbicides for safety in

carrots and the level of weed control at rates safe on carrot.

Materials and Methods
Greenhouse studies
Screening studies were conducted in the MSU Plant Science Greenhouse at
Michigan State University in 2001 and 2002 to determine carrot sensitivity to several
new herbicides (Tables 1 and 2). Carrot ‘Apache’ seeds were planted in 30 x 30 cm

plastic ﬂats. The seeds were sown in rows at a rate of 75 seeds per ﬂat, 25 seeds per row.

26

Table 1. Greenhouse preemergence herbicide treatments on carrot in 2001 and 2002

 

 

 

Treatments Rate
Common name Trade name (Kg ai/ha)
Linuron Lorox 50DF 0.561
Flumioxazin Valor 51WG 0.0011
Flumioxazin Valor 51WG 0.0056
Flumioxazin Valor 51WG 0.0112
Oxyﬂuorfen Goal XL 2L 0.112
Oxyﬂuorfen Goal XL 2L 0.224
Oxyﬂuorfen Goal XL 2L 0.448
Clomazone Command 3ME 0.280
Clomazone Command 3ME 0.560
Clomazone Command 3ME 1.121
Clomazone Command 3ME 2.242
Sulfentrazone Spartan 75DF 0.112
Sulfentrazone Spartan 75DF 0.224
Azafenidin Milestone 80DF 0.112
Azafenidin Milestone 80DF 0.224
Flufenacet + metribuzin Domain 60DF 0.09 + 0.135
F lufenacet + metribuzin Domain 60DF 0.179 + 0.269
F lufenacet + metribuzin Domain 60DF 0.359 + 0.538
Flufenacet + metribuzin Domain 60DF 0.717 + 1.076
Mesotrione Callisto 4SC 0.022
Mesotrione Callisto 4SC 0.045
Mesotrione Callisto 4SC 0.090
Mesotrione Callisto 4SC 0.179

 

27

Table 2. Greenhouse postemergence herbicide treatments on carrot in 2001 and 2002

 

 

 

Treatments Rate
Common name Trade name (Kg ai/ha)
Linuron Lorox 50DF 0.561
Flumioxazin Valor 51WG 0.036
Flumioxazin Valor 51WG 0.053
Flumioxazin Valor 51WG 0.071
Oxyﬂuorfen Goal XL 2L 0.035
Oxyﬂuorfen Goal XL 2L 0.070
Oxyﬂuorfen Goal XL 2L 0.140
Mesotrione Callisto 4SC 0.022
Mesotrione Callisto 4SC 0.045
Mesotrione Callisto 4SC 0.090
Mesotrione Callisto 4SC 0.179
Carfcntrazone Aim 40DF 0.01 l
Carfcntrazone Aim 40DF 0.022
Prometryn Caparol 4L 1 . 121
Sulfentrazone Spartan 75DF 0.112
Sulfentrazone Spartan 75DF 0.224

 

28

The media used was soil collected ﬂom the MSU Horticulture Teaching and Research
Center for mineral soil and ﬂom the MSU Muck Research Farm for organic soil. The
soil type ﬂom the MSU Horticulture Teaching and Research Center was a Marlette ﬁne
sandy loam, pH 6.1, with 2.0% organic matter. The soil type ﬂom the MSU Muck Farm
was Houghton Muck, pH 6.3, with 80% organic matter. Carrot seedlings were fertilized
weekly with a solution of 20N-8.6P-16.6K at the rate of 300 mg/L. Irrigation was
applied as needed. Flats were hand weeded as required.

Preemergence and postemergence experiments were conducted to determine
carrot tolerance to several new herbicides. Preemergence herbicides were applied three
days after seeding. Postemergence herbicides were applied when carrots reached the 4 to
5 leaf stage. Herbicides were applied with a traveling-belt bench sprayer equipped with
an 8001E ﬂat-fan nozzle and calibrated at 1.5 km/h, 187 L/ha, and 152 kPa. Stand
counts, crop injury, and crop biomass measurements were collected. Crop injury ratings
were conducted using a scale of 1 to 10, where 1 represented no injury and 10
represented plant death. Crop injury ratings were converted to percentage for
presentation. Visual crop injury ratings were made at 7, l4 and 28 days after treatment
(DAT). Stand counts were assessed at 14 and 28 DAT and at harvest. Whole plants were
harvested 50 to 60 days after sowing and ﬂesh weight was measured. The carrot plants
were dried at 50 C for 7 days and dry weights were recorded. The experimental design
was a randomized complete block with four replications; each ﬂat was considered to be
replication. The preemergence and postemergence treatments are listed in Table 1; all

treatments were compared to an untreated control. These experiments were repeated

29

three times. Statistical analyses were conducted independently for each experiment due

to interaction found between experiment and time of the year.

Field Studies

Field studies were conducted in 2001, 2002 and 2003 to evaluate carrot tolerance
to several new herbicides under ﬁeld conditions (Tables 3 - 8). Sites included
commercial ﬁelds in Oceana and Newaygo counties in 2001, 2002, and 2003, and at the
MSU Muck Research Farm (Muck Farm) in Laingsburg in 2003. These three locations
represent two major Michigan carrot production areas and two main soil types. The soil
type at the Oceana site was a Spinx-Benona complex with 1.6% organic matter, 83%
sand, 11% silt, 6% clay and pH 6.7. Soil type at the Newaygo location was a Pipestone
Sand complex with 2.4% organic matter, 88% sand, 7% silt, 5% clay, and pH 6.9. Soil
type at the Muck Farm was a Houghton Muck soil with 80% organic matter and pH 6.3.
Site details are presented in Table 9.

Cultural practices and carrot cultivars used in these studies were typical for each
location. Carrot seeds were sown in three lines per bed with a commercial planter in
early May 2001, 2002, and 2003 at the Oceana location, late May 2003 at the Muck
Farm, and three triple lines per bed in early May 2001, 2002, and 2003 at the Newaygo
location. Plot size was 1.4 m wide (1 bed) by 10 m long. The experimental design was a
randomized complete block with three replications in all the studies. Herbicide treatments
were applied preemergence and postemergence. The herbicides used in this study are
listed in Tables 3 - 8. In 2001 and 2002, all experiments had an untreated control plot. In

2003 all experiments had a hand-weeded control plot. A linuron treated check-plot was

30

Table 3. List of herbicide treatments and rates applied on carrot in Oceana County during 2001

 

 

Preemergence Postemergence
Rate Rate
Treatment Trade Name (kg ai/ha) Treatment Trade Name (kg ai/ha)
Linuron Lorox 50DF 0.280 Linuron a Lorox 50DF 0.280
Linuron Lorox 50DF 0.561 Linuron a Lorox 50DF 0.561
Flumioxazin Valor 51WG 0.001 Flumioxazin a Valor 51WG 0.036
Flumioxazin Valor 51WG 0.006 Flumioxazin a Valor 51WG 0.053
Flumioxazin Valor 51WG 0.01 1 F lumioxazin Valor 51WG 0.036
S-metolachlor Dual Magnum 0.561 Flumioxazin Valor 51WG 0.053
7.62EC
Pendimethalin Prowl 3.3EC 0.841 F lumioxazin Valor 51WG 0.070
Sulfentrazone Spartan 75DF 0.112 Oxyﬂuorfen Goal XL 2L 0.035
Flufenacet Deﬁne 60DF 0.336 Mesotrione Callisto 4SC 0.011
.. mm...— 3;;3:+ 22:22:: mm 3232+
Pelargonic acid Scythe 3.810

 

 

a Treatment + clethodirn 0.112 kg ai/ha + NIS 0.25% WV

31

Table 4. List of herbicide treatments and rates applied on carrot in Oceana County during 2002

 

 

Preemergence Postemergence

Rate Rate
Treatment Trade Name (kg ai/ha) Treatment Trade Name (kg ai/ha)
Linuron Iorox 50DF 0.561 Linuron Lorox 50DF 0.561
Oxyﬂuorfcn Goal XL 2L 0.1 12 F lumioxazin Valor 51WG 0.036
Oxyﬂuorfen Goal XL 2L 0.224 Flumioxazin Valor 51WG 0.053
Flumioxazin Valor 51WG 0.006 Flumioxazin Valor 51WG 0.071
Flumioxazin Valor 51WG 0.01 1 Oxyﬂuorfen Goal XL 2L 0.035
S-metolachlor 17316lazllihéfagnum 0.561 Oxyﬂuorfen Goal XL 2L 0.070
Pendimethalin Prowl 3.3EC 0.841 Sulfentrazone Spartan 75DF 0.056
Sulfentrazone Spartan 75DF 0.1 12 22:23:: + Domain 60DF 333% +
Flufenacet Deﬁne 60DF 0.336 23:33:: + Domain 60DF 3216): +
22:33: + Domain 60DF 333: + Mesotrione Callisto 4SC 0.022
Clomazone Command 3ME 0.28 Mesotrione Callisto 4SC 0.045

 

 

32

Table 5. List of herbicide treatments and rates applied on carrot in Oceana County during 2003

 

 

Preemergence Postemergence

Rate Rate
Treatment Trade Name (kg ai/ha) Treatment Trade Name (kg ai/ha)
Linuron Lorox 50DF 0.561 Linuron a Lorox 50DF 0.561
Clomazone Command 3ME 0.280 Linuron Lorox 50DF 1.121
Clomazone Command 3ME 0.561 Oxyﬂuorfen Goal XL 2L 0.035
Clomazone Command 3ME 1.121 Oxyﬂuorfen Goal XL 2L 0.070
Mesotrione Callisto 4SC 0.112 Oxyﬂuorfen Goal XL 2L 0.140
Mesotrione Callisto 4SC 0.224 Flumioxazin Valor 51WG 0.036
Mesotrione Callisto 4SC 0.448 Flumioxazin Valor 51WG 0.070
22:23:: + Domain 60DF 3&2: + Mesotrione b Callisto 4SC 0.0'5
2:333? Domain 60DF 8:333 + Mesotrione b Callisto 4SC 0.105
Metribuzin Sencor 75DF 0.420 Mesotrione Callisto 4SC 0.050
Flufenacet Deﬁne 60DF 0.673 Mesotrione Callisto 4SC 0.105

 

 

a Treatment + COC 1% WV
bTreatment + COC 1% WV + UAN 2.5% WV

33

Table 6. List of herbicide treatments and rates applied on carrot in Newaygo County during 2001 and 2002

 

 

Postemergence treatments 2001 Postemergence treatments 2002

Rate Rate
Treatment Trade Name (kg ai/ha) Treatment Trade Name (kg ai/ha)
Linuron ‘1 Lorox 50DF 0.280 Linuron Lorox 50DF 0.561
Linuron a Lorox 50DF 0.561 Flumioxazin Valor 51WG 0.036
Flumioxazin Valor 51WG 0.036 Flumioxazin Valor 51WG 0.053
Flumioxazin a Valor 51WG 0.036 Flumioxazin Valor 51WG 0.070
Flumioxazin Valor 51WG 0.053 Oxyﬂuorfen Goal XL 2L 0.035
Flumioxazin a Valor 51WG 0.053 Oxyﬂuorfen Goal XL 2L 0.071
Oxyﬂuorfen Goal XL 2L 0.035 Oxyﬂuorfen Goal XL 2L 0.140
F luthiacet Action 4.75WP 0.0038 Mesotrione Callisto 4SC 0.045
Flumiclorac Resource 0.86EC 0.045 Sulfentrazone Spartan 75DF 0.056
Carfcntrazone Aim 40DF 0.01 1 Sulfentrazone Spartan 75DF 0.112

 

 

aTreatment + sethoxydirn 0.213 kg ai/ha + NIS 0.25% WV

34

Table 7. List of herbicide treatments and rates applied on carrot in Newaygo County location during 2003

 

 

 

Preemergence Postemergence

Rate Rate
Treatment Trade Name kg ai/ha Treatment Trade Name kg ai/ha
Linuron Lorox 50DF 0.280 Linuron a Lorox 50DF 0.280
Linuron Lorox 50DF 0.561 Linuron a Lorox 50DF 0.561
Clomazone Command 3ME 0.280 Linuron Lorox 50DF 1.121
Clomazone Command 3ME 0.561 Oxyﬂuorfen Goal XL 2L 0.035
Mesotrione Callisto 4SC 0.1 12 Oxyﬂuorfen Goal XL 2L 0.070
Mesotrione Callisto 4SC 0.224 Oxyﬂuorfen Goal XL 2L 0.140
22:33:: Domain 60DF 3323 + Flumioxazin Valor 51WG 0.036
23:33:: Domain 60DF 33,3: + Flumioxazin Valor 51WG 0.070
Metribuzin Sencor 75DF 0.420 Mesotrione Callisto 4SC 0.050
Flufenacet Deﬁne 60DF 0.673 Mesotrione Callisto 4SC 0.105

 

a Treatment + COC 1% V/V

35

Table 8. List of herbicide treatments and rates applied on carrot at the Muck Farm during 2003

 

 

Preemergence Postemergence

Rate Rate
Treatment Trade Name kg ai/ha Treatment Trade Name kg. ai/ha
Linuron Lorox 50DF 1.121 Linuron “ Lorox 50DF 1.121
S-metolachlor 173.23???“ 1.900 Triﬂoxysulfuron 3‘32“ 75 0.0075
Pendimethalin Prowl 3.3EC 2.240 Oxyﬂuorfen Goal XL 2L 0.035
Clomazone Command 3ME 0.280 Oxyﬂuorfen Goal XL 2L 0.07 0
Clomazone Command 3ME 0.561 Oxyﬂuorfen Goal XL 2L 0.140
Mesotrione Callisto 4SC 0.1 12 F lumioxazin Valor 51WG 0.036
Mesotrione Callisto 4SC 0.224 Flumioxazin Valor 51WG 0.071
Mesotrione Callisto 4SC 0.448 Mesotrione Callisto 4SC 0.050
2:31:23: Domain 60DF 3313: + Mesotrione Callisto 4SC 0.105
Metribuzin Sencor 75DF 0.561 Mesotrione b Callisto 4SC 0.050
Flufenacet Deﬁne 60DF 0.673 Mesotrione b Callisto 4SC 0.105

 

 

aTreatment + COC 1% WV

bTreatment + COC 1% WV + UAN 2.5% WV

36

Table 9. Field experiments site details

 

 

Oceana County Newaygo County MSU Muck F arm

Cultivar Type

2001 Goliath (P)a Bergen (P) Goliath (P)

2002 Canada (P) Sugarsnax (F) N/A

2003 Recolleta (P) Sugarsnax (F) Apache (F)
Seeding rate 670,000 seeds/ha 2,000,000 seeds/ha 1,350,000 seeds/ha
Soil type Spinx-Benona Pipestone Sand Houghton Muck

Sand 83% 88% N/A

Silt 11% 7% N/A

Clay 6% 5% N/A

Organic matter 1.6% 2.4% 80%

pH 6.7 6.9 6.3

 

a P = Processing variety; F = Fresh market variety

37

included among the treatments in all studies. Herbicides were applied using a CO;
pressurized backpack sprayer and a 1.2 m boom with four FF8002 nozzles at 187 um
volume, pressure of 207 kPa, and a speed of 5.3 km/h.

Stand counts, crop injury, weed control ratings, and yields were collected. Crop
injury was rated for all experiments at 7, 14, and 21 DAT. Crop injury and weed control
estimates were done on a scale of 1 to 10, where 1 represented no injury and 10
represented complete plant death. The visual rating scale was converted to percentage for
analysis. The carrot stands of preemergence studies were assessed in 1 linear meter of
bed at 14 DAT. Yields were obtained in mid September by harvesting 1.5 m of all three
rows near the center of each plot. Fresh weight of carrot roots was recorded.

Experiments were arranged in a randomized complete block design with three
replications. Data ﬂom each experiment were subjected to analysis of variance using
SAS program (SAS, 1990). Fisher’s Protected LSD at a = 0.05 signiﬁcance level was

used to detect differences between treatment means.

Results and Discussion
Greenhouse Studies
Greenhouse screening studies were conducted to determine carrot sensitivity to
several new herbicides. Herbicides that appeared to be safe on carrot were selected and
further studies were conducted under ﬁeld conditions.
Preemergence herbicides
Flumioxazin preemergence at 0.0011 and 0.0056 kg/ha demonstrated low toxicity

to carrot, and did not reduce stand counts or biomass. When ﬂumioxazin rate was

38

increased to 0.0112 kg/ha results were inconsistent. In one experiment, carrot stand was
reduced signiﬁcantly and biomass tended to decrease but was not signiﬁcantly different
compared to the untreated control. In the other experiment, stand count and biomass did
not differ compared to the untreated control (Tables 10, 11, 12, and 13).

Azafenidin at 0.112 kg/ha was highly toxic to carrot. Applied preemergence,
azafenidin killed all carrots. Sulfentrazone at 0.112 and 0.224 kg/ha was toxic to carrot,
reducing stand count and biomass (Tables 10 and 11).

Clomazone at 0.280, 0.561, and 1.12 kg/ha was safe on carrot. It caused low
initial injury, similar to the injury caused by linuron at 0.561 kg/ha. Stand counts and
biomass did not decrease. Clomazone at 2.24 kg/ha caused slightly higher injury
compared to the lower rates. Stand counts and biomass were not affected (Tables 10, 13,
and 14).

Domain (ﬂufenacet 24% plus metribuzin 36%) at 0.224 and 0.448 kg/ha was safe
for carrot. Domain at those rates caused minimal initial injtu'y which was not different
ﬂom linuron at 0.561 kg/ha. Stand counts and biomass were similar to the untreated
control. Domain at 0.897 kg/ha caused slightly higher initial crop injury. However,
Domain at 1.79 kg/ha was toxic to carrot, causing signiﬁcant initial injury and stand
count and biomass reduction (Tables 10 and 14).

Mesotrione preemergence at 0.022, 0.045, 0.090 and 0.179 kg/ha was safe for
carrot. Initial injury was minimal at 0.022 kg/ha and increased slightly at 0.045, 0.090,
and 0.179 kg/ha, although it was not signiﬁcant. Stand count and biomass reduction was

not observed (Tables 10 and 14).

39

Table 10. Summary of the effect of preemergence herbicides on carrot grown in the greenhouse.

 

 

Herbicide “(IE/:3) Toxicity to carrot Comments

Flumioxazin 0.001 1 Low

Flumioxazin 0.0056 Low

Flumioxazin 0.0112 Moderate Irregular. One time safe, one time moderate
Azafenidin 0.1 12 High Completely killed plants

Azafenidin 0.224 High Completely killed plants

Oxyﬂuorfen 0. 1 12 Low

Oxyﬂuorfen 0.224 Low Low. Initial crop injury higher than linuron
Ox yﬂuo rfen 0. 448 Moderate 31:51:11,233; 2:16 safe, one time moderate.
Sulfentrazone 0.1 12 High Signiﬁcant reduction in stand and biomass
Sulfentrazone 0.224 High Signiﬁcant reduction in stand and biomass
Clomazone 0.280 Low

Clomazone 0.56 1 Low

Clomazone 1 . 12 Low

Clomazone 2.24 Low Crop injury slightly higher

Domain a 0.224 Low

Domain 0.448 Low

Domain 0.897 Low Crop injury slightly higher

Mesotrione 0.0224 Low

Mesotrione 0.0448 Low

Mesotrione 0.0897 Low

Mesotrione 0.179 Low Crop injury slightly higher

 

a Flufenacet 24% plus metribuzin 36%

40

Table 11. Effect of preemergence herbicides on carrot stand and ﬂesh weight applied in the greenhouse on

 

 

 

March 2001.
Stand count Fresh weight

Rate No. of plants per ﬂat 3 g/ ﬂat
Treatment (kg ai/ha) .35 DAT 66 DAT 66 DAT
Flumioxazin 0.0011 73.7 ab 69.7 a 10.0 ab
Flumioxazin 0.0056 57.7 abc 59.3 ab 9.3 ab
Flumioxazin 0.0112 39.0 c 38.0 b 5.8 bc
Azafenidin 0.112 0.0 d 0.0 c 0.0 d
Azafenidin 0.224 0.0 d 0.0 c 0.0 d
Oxyﬂuorfen 0.224 55.0 abc 53.7 ab 7.7 abc
Oxyﬂuorfen 0.448 45.0 be 30.0 b 3.7 cd
Linuron 0.561 74.7 a 68.3 a 12.1 a
Untreated control 57.3 abc 56.0 ab 7.1 bc
LSD (005, 28.805 29.762 4.5

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a 100 seeds were planted per 900 cm2 ﬂat

41

Table 12. Effect of preemergence herbicides applied in the greenhouse on May 2001, on carrot stand and

 

 

 

ﬂesh weight.
Stand count Fresh weight

Rate No. of plants per ﬂat a g/ ﬂat
Treatment (kg ai/ha) 35 DAT 66 DAT 66 DAT
Flumioxazin 0.0011 65.3 a 64.3 a 18.9 abc
Flumioxazin 0.0056 64.5 a 60.5 ab 19.0 abc
Flumioxazin 0.0112 54.8 abc 54.8 abc 20.7 ab
Oxyﬂuorfen 0.224 42.5 de 41.3 de 18.9 abc
Oxyﬂuorfen 0.448 49.5 cde 48.5 cde 17.9 abc
Sulfentrazone 0.112 47.3 cde 45.8 cde 16.6 c
Sulfentrazone 0.224 40.5 c 37.5 c 17.3 be
Linuron 0.561 53.3 bcd 51.0 bcd 20.9 a
Untreated control 61.5 ab 60.3 ab 20.5 ab
LSD (0.05, 10.9 11.2 3.5

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a 75 seeds were planted per 900 cm2 ﬂat

42

Table 13. Effect of preemergence herbicides applied in the greenhouse on April 2002, on carrot stand,
injury level, and ﬂesh weight.

 

 

 

Stand count Crop injury b Fresh weight

Rate No. of plants per ﬂat a (0/0) g/ﬂat
Treatment (kg ai/ha) 14 DAT 14 DAT 21 DAT 28 DAT 58 DAT
linuron 0.561 57.3 b 8.9 cde 11.1 be 11.1 b 16.2 b
ﬂumioxazin 0.0011 62.3 ab 5.5 cde 3.3 cd 3.3 bc 16.1 b
ﬂumioxazin 0.0056 57.0 b 11.1 cd 8.9 bcd 5.5 be 17.0 ab
oxyﬂuorfen 0.112 62.3 ab 14.4 be 11.1 be 8.9 be 16.3 ab
oxyﬂuorfen 0.224 59.8 b 22.2 ab 16.7 b 5.5 be 16.8 ab
oxyﬂuorfen 0.448 59.3 b 31.1 a 31.1 a 22.2 a 16.5 ab
clomazone 0.280 59.0 b 5.5 cde 3.3 cd 3.3 be 19.1 a
clomazone 0.561 67.1 a 1.1 e 0.0 d 0.0 c 19.1 a
Untreated control 62.3 ab 3.3 de 0.0 d 0.0 c 17.7 ab
LSD (005, 6.7 10.0 10.0 10.0 2.8

 

Values followed by the same letter in the same column are not statistically significant at (1 =0.05
a 75 seeds were planted per 900 cm2 ﬂat

b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death.

43

Table 14. Effect of preemergence herbicides applied in the greenhouse on March 2003, on carrot stand,
injury level, and ﬂesh weight.

 

 

 

Stand count Crop injury b Fresh weight

Rate No. of plants per ﬂat 3 (%) g/ﬂat
Treatment (kg ai/ha) 19 DAT 60 DAT 19 DAT 60 DAT
Linuron 1.120 64.3 a 56.7a 11.1 be 14.0 ab
clomazone 0.561 62.3 ab 57.0 a 11.1 be 13.6 ab
clomazone 1.120 63.0 ab 50.3 ab 11.1 be 10.2 bc
clomazone 2.240 60.7 ab 53.0 ab 25.5 abc 11.2 ab
Domainc 0.224 58.7 ab 48.3 ab 7.8 be 12.3 ab
Domain 0.448 62.3 ab 57.7 a 11.1 be 12.4 ab
Domain 0.897 56.7 ab 51.0 ab 22.2 abc 11.0 ab
Domain 1.790 40.7 c 34.0 c 36.7 a 6.7 c
mesotrione 0.022 59.7 ab 57.3 a 3.3 c 12.1 ab
mesotrione 0.045 54.3 abc 48.0 abc 18.9 abc 11.7 ab
mesotrione 0.090 49.3 be 47.0 abc 18.9 abc 11.8 ab
mesotrione 0.179 51.3 abc 49.3 ab 30.0 ab 11.8 ab
Untreated control 58.3 ab 50.0 ab 7.8 be 14.5 a
LSD (0.051 14.0 14.0 24.4 3.8

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a 75 seeds were planted per 900 cm2 ﬂat

b Visually assessed crop injury at scale of 0 to 100%; O= no injury and 100% = plant death.

c Flufenacet 24% plus metribuzin 36%

Postemergence herbicides

Flumioxazin postemergence at 0.022 kg/ha demonstrated low toxicity to carrot.
Stand counts and biomass of carrot treated with ﬂumioxazin at 0.022 were similar to the
untreated control. When ﬂumioxazin rate was increased to 0.036, 0.044, and 0.053
kg/ha, stand counts were not different ﬂom the untreated control and biomass was not
statistically different compared to untreated control. However, there was a trend of
decreasing weight (Tables 15, 16, 17, and 18). Results of ﬂumioxazin at 0.067 kg/ha
were variable. In one experiment, stand counts were reduced and biomass was
signiﬁcantly different compared to the untreated control. In another experiment, there
was no reduction in stand counts and biomass. Flumioxazin at 0.071 kg/ha caused
stunting in carrot but there was no effect on stand counts. Biomass was reduced and
statistically different compared to untreated control but it was not signiﬁcantly different
when compared to linuron at 0.561 kg/ha.

Oxyfluorfen postemergence at 0.03 5, 0.070, and 0.140 kg/ha was safe on carrot.
There was no signiﬁcant stand count or biomass reduction. However, initial injury was
higher at all rates of oxyﬂuorfen when compared to linuron at 0.561 kg/ha (Tables 15, 16,
17,18, and 19).

Carfcntrazone postemergence at 0.011 kg/ha was moderately toxic to carrot. In
one experiment there was no stand reduction but biomass was signiﬁcantly reduced
compared to the untreated control. In another experiment, both stand and biomass were
signiﬁcantly reduced compared to the untreated control. Carfcntrazone at 0.022 kg/ha
was highly toxic to carrot signiﬁcantly reducing both stand counts and biomass compared

to the untreated control (Tables 15, 16, and 17).

45

Table 15. The effect of postemergence herbicides on carrot grown in the greenhouse -— summary of results.

 

Rate

 

Herbicide Toxici to carrot Comments
(Kg/ha) ‘1

ﬂumioxazin 0.022 Low

ﬂumioxazin 0. 03 6 Low Imtral crop mjury high. Slight ﬂesh welght
reductron

ﬂumioxazin 0.045 Low Slight biomass reduction

ﬂumioxazin 0.053 Low Slight biomass reduction

ﬂumioxazin 0.067 Moderate to high Vanable results. Stand and ﬂesh welght
sometimes reduced
Initial crop injury high. Fresh weight reduced

ﬂumioxazin 0.070 Moderate but no signiﬁcant difference compared to
linuron

oxyﬂuorfen 0.035 Low Initial crop injury slightly high

oxyﬂuorfen 0.070 Low Initial crop injury slightly high
Initial crop injury slightly high. Slight ﬂesh

oxyﬂuorfen 0'140 Low weight reduction (variable)

carfentrazone 0.01 1 Moderate to high Fresh welght reduction, occasronal stand
reductlon

carfentrazone 0022 High Stand reduction and srgnlﬁcant blomass
reduction

mesotrione 0.022 Low

mesotrione 0.045 Low

mesotrione 0.090 Low Tendency to reduce ﬂesh weight

mesotrione 0.179 Moderate Fresh weight reduction

 

46

Table 16. Effect of postemergence herbicides applied in the greenhouse on March 2001, on carrot stand
and ﬂesh weight.

 

 

 

Stand count Fresh weight

Rate No. of plants per ﬂat a g/ﬂat
Treatment (kg ai/ha) , 0 DAT 24 DAT 24 DAT
ﬂumioxazin 0.022 85.3 a 79.0 a 19.3 ab
ﬂumioxazin 0.045 86.5 a 80.5 a 15.2 bcd
ﬂumioxazin 0.067 82.3 ab 57.5 b 11.1 de
oxyﬂuorfen 0.035 73.3 ab 72.5 ab 17.6 abc
oxyﬂuorfen 0.070 73.3 ab 73.5 ab 20.9 ab
oxyﬂuorfen 0.140 82.8 ab 81.3 a 15.7 bed
carfentrazone 0.011 73.3 ab 70.8 ab 12.6 cde
carfentrazone 0.022 69.0 b 57.8 b 7.2 e
linuron 0.561 80.3 ab 79.8 a 21.9 a
Untreated control 74.5 ab 74.0 ab 17.5 abc
LSD (0.05, 15.4 16.6 5.8

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a 100 seeds were planted per 900 cm2 ﬂat

47

Table 17. Effect of postemergence herbicides applied in the greenhouse on May 2001, on carrot stand and
ﬂesh weight.

 

 

 

Stand count Fresh weight

Rate No. of plants per ﬂat 3 g/ ﬂat
Treatment (kg ai/ha) , 0 DAT 32 DAT 32 DAT
ﬂumioxazin 0.022 62.3 a 62.3 ab 20.6 ab
ﬂumioxazin 0.045 63.3 a 60.5 abc 18.6 b
ﬂumioxazin 0.067 63.8 a 59.5 abc 18.5 b
oxyﬂuorfen 0.035 60.0 a 59.8 abc 21.4 ab
oxyﬂuorfen 0.070 61.5 a 56.0 be 18.4 b
oxyﬂuorfen 0.140 60.0 a 57.5 abc 19.5 b
carfentrazone 0.011 59.5 a 53.3 c 13.4 c
carfentrazone 0.022 65.3 a 44.0 d 7.5 d
linuron 0.561 62.5 a 62.0 ab 23.9 a
Untreated control 64.3 a 64.0 a 21.7 ab
LSD (00,, NS b 7.9 3.8

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a 75 seeds were planted per 900 cm2 ﬂat

b No signiﬁcant difference

48

Table 18. Effect of postemergence herbicides applied in the greenhouse on April 2002, on carrot stand,
injury level, and ﬂesh weight.

 

 

 

 

Stand count Crop injury b Fresh weight

Rate No. of plants per ﬂat a g/ﬂat
Treatment (kg tha) 0 DAT 28 DAT 7 DAT 14 DAT 60 DAT
linuron 0.561 61.3 a 59.5 a 8.9 d 0.0 b 15.2 bc
ﬂumioxazin 0.035 60.0 a 58.8 a 27.8 ab 14.4 a 13.9 c
ﬂumioxazin 0.053 62.3 a 60.8 a 22.2 c 20.0 a 14.7 be
ﬂumioxazin 0.070 63.5 a 62.5 a 22.2 c 16.7 a 14.0 c
oxyﬂuorfen 0.035 64.0 a 62.8 a 25.5 be 5.5 b 15.8 abc
oxyﬂuorfen 0.070 63.8 a 61.8 a 22.2 c 3.3 b 15.3 be
oxyﬂuorfen 0.140 60.0 a 59.3 a 31.1 a 0.0 b 16.7 abc
mesotrione 0.022 59.3 a 56.8 a 11.1 d 0.0 b 19.0 a
mesotrione 0.044 63.8 a 61.3 a 11.1 d 3.3 b 17.3 abc
Untreated control 59.8 a 60.5 a 0.0 e 0.0 b 17.8 ab
LSD (0.05) NS ° NS 5.6 7.8 3.6

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a 75 seeds were planted per 900 cm2 ﬂat

b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death.

c No signiﬁcant difference

49

Table 19. Effect of postemergence herbicides applied in the greenhouse on March 2003, on carrot stand,
injury level, and ﬂesh weight.

 

 

Stand count Crop injury b Fresh weight

Rate No. of plants per ﬂat 3 (%) g/ﬂat
Treatment (kg ai/ha) 48 DAT 7 DAT 48 DAT
Linuron 0.561 55.7 ab 14.4 ed 18.2 ab
Linuron 1.121 50.3 ab 14.4 ed 16.7 be
oxyﬂuorfen 0.035 55.7 ab 41.1 b 20.2 ab
oxyﬂuorfen 0.070 52.0 ab 52.2 a 16.2 bc
oxyﬂuorfen 0.106 56.3 ab 44.4 ab 19.7 ab
oxyﬂuorfen 0.142 49.0 ab 52.2 a 17.0 be
mesotrione 0.022 62.7 a 14.4 cd 18.4 ab
mesotrione 0.044 57.3 ab 11.1 d 18.3 ab
mesotrione 0.090 51.3 ab 18.9 cd 16.6 bc
mesotrione 0.179 46.7 b 22.2 c 13.4 c
Untreated control 47.0 b 0.0 c 22.4 a
LSD (0.05, 14.7 8.9 4.5

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a 75 seeds were planted per 900 cm2 ﬂat
b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death.

50

Mesotrione postemergence at 0.022 and 0.044 kg/ha had low toxicity to carrot.
Initial injury level, stand counts, and biomass were similar to linuron at 0.561 kg/ha.
Mesotrione at 0.090 kg/ha had a tendency to reduce carrot biomass. Biomass was not
different compared to linuron at 0.561 kg but was signiﬁcantly different when compared
to the untreated control. Mesotrione at 0.179 kg/ha reduced biomass signiﬁcantly

compared to linuron and the untreated control (Tables 15, 18, and 19).

Field Studies

 

F lumioxazin preemergence:

Flumioxazin preemergence at 0.001 1 kg/ha in mineral soil at Oceana County in
2001 was safe on carrot with no signiﬁcant difference compared to linuron at 0.56 kg/ha
for stand count, injury, and yield (Table 20). When the ﬂumioxazin rate was increased to
0.0056 and 0.011 kg/ha in 2001 and 2002, a signiﬁcant decrease of stand and a higher
level of injury appeared. Visual injury was rated at 22.2% 35 DAT for both ﬂumioxazin
rates in 2001 and 36.7% 42 DAT in 2002. Carrot yield with ﬂumioxazin at 0.0056 kg/ha
was not different ﬂom linuron at 0.561 kg/ha in 2001; however, yield decreased
signiﬁcantly in 2002. With ﬂumioxazin at 0.011, carrot yield decreased signiﬁcantly in
2001 and 2002 (Table 20).

Flumioxazin at 0.0011 had fair control (67%) of common lambsquarters
(Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.), and poor
control (< 30%) of shepherd's-purse (Capsella bursa-pastoris L.) at Oceana County in
2001 (Appendix 5). At the same rate, control of eastern black nightshade (Solanum

ptycanthum Dun.) was 83%. Weed control improved at 0.0056 and 0.011 kg/ha. For

51

Table 20. The effect of preemergence ﬂumioxazin on carrot stand, injury, and yield in the ﬁeld.

 

 

 

Stand count Crop injﬂﬂ b - Yield
(plants/1m of bed) a (%) (kg/1.5m of bed)
Rate Oceana Oceana Oceana Oceana Oceana Oceana
. 2001 2002' 2001 2002 2001 2002
Treatment (kg am“) 35 DAT 127 DAT 35 DAT 42 DAT 125 DAT 127DAT
Linuron 0.280 26.7 a 0.0 b 14.6 a
Linuron 0.561 22.0 b 69.5 ab 0.0 b 14.4 ab 14.2 ab 7.0 b
Flumioxazin 0.001 22.7 ab 7.8 b 13.9 ab
Flumioxazin 0.006 16.7 c 36.0 be 22.2 a 36.7 a 11.8 be 1.0 e
Flumioxazin 0.011 15.0 c 17.3 c 22.2 a 36.7 a 10.4 c 0.6 c
Untreated 24.3 ab 97.3 a 7.8 b 0.0 b 10.0 c 9.9 a
LSD (0.05) 4.1 35.3 13.3 24.4 2.7 2.6

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

8‘ Carrots were planted on beds. Each bed had 3 rows
b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death.

52

common lambsquarters and redroot pigweed, control was 93% at both rates, and for
shepherd's-purse control was 73% with 0.0056 kg/ha of ﬂumioxazin and 90% with 0.011
kg/ha of ﬂumioxazin. With both rates, control of eastern black nightshade was 100%
(Appendix 5). However, in 2002 at Oceana County, weed control with ﬂumioxazin at
0.0056 and 0.011 kg/ha was lower than in 2001. Control of redroot pigweed was of 53%
at a rate of 0.0056 kg/ha and 93% at a rate of 0.011 kg/ha. Control of ladysthumb
(Polygonum persicaria L.) was marginal (< 20%) at both rates and common
lambsquarters was controlled 70% at 0.0056 kg/ha and 37% at 0.011 kg/ha. Common
ragweed (Ambrosia artemisiifolia L.) control was 30% at 0.0056 kg/ha and 53% at 0.011
kg/ha in 2002, black medic (Medicago lupulina L.) with less than 45% control at both
rates, and common chickweed (Stellaria media L.) with 70% control at both rates.
Control of those weeds decreased considerably 11 weeks after treatment (Appendixes 10

and 13).

F lumioxazin postemergence:

Carrot had moderate tolerance to postemergence ﬂumioxazin at 0.053 kg/ha in
2001 and 2002 at Newaygo and Oceana County. Stand count and yield were not
signiﬁcantly different ﬂom linuron at 0.561 kg/ha (Tables 21 and 23). Crop injury
caused by ﬂumioxazin at 0.053 kg/ha 7 DAT was not different ﬂom linuron in 2001 at
Oceana County (Table 22). However, ﬂumioxazin crop injury was signiﬁcantly higher in
Newaygo in 2001 and 2003 and Oceana in 2002 and 2003 compared to linuron (Table
22). F lumioxazin at 0.070 kg/ha injured carrot seven DAT but did not reduce stand

counts and yield at Oceana in 2001 and 2003, and at Newaygo 2003. Results in 2002

53

Table 21. The effect of postemergence ﬂumioxazin on carrot stand, 2001 and 2002.

 

 

 

Stand count
(Plants/m ofbed) a
Rate Newaygo Oceana Oceana
. 2001 2001 2002

Treatment (kg tha) 99 DAT 99 DAT 84 DAT
Linuron 0.280 65.0 a 25.3 a
Linuron 0.561 63.0 a 24.7 a 92.3 a
Flumioxazin 0.035 56.3 a 21.3 a 79.3 a
Flumioxazin 0.053 60.0 a 24.0 a 89.7 a
Flumioxazin 0.070 23.0 a 90.0 a
Untreated 59.0 a 23.0 a 101.0 a
LSD (00,, NS b NS NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b No signiﬁcant difference

54

Table 22. The effect of postemergence ﬂumioxazin on carrot injury, 2001, 2002, and 2003.

 

 

 

Carrot injury (%) 3'
Muck
Rate Newaygo Oceana Oceana Newaygo Oceana Farm
. 2001 2001 ' 2002 2003 2003 2003
Treatment (kg am”) 7 DAT 7 DAT 7 DAT 14 DAT 14 DAT 14 DAT
Linuron 0.280 0.0 b 3.3 c 3.3 d
Linuron 0.561 7.8 b 3.3 c 3.3 b 14.4 c 7.8 be
Linuron 1.121 25.5 b 14.4 b 3.3 bc
Flumioxazin 0.035 66.7 a 14.4 ab 18.9 a 44.4 a 30.0 a 11.1 ab
Flumioxazin 0.053 74.4 a 7.8 be 22.2 a
Flumioxazin 0.070 22.2 a 22.2 a 44.4 a 33.3 a 18.9 a
Untreated 0.0 b 0.0 c 0.0 b 0.0 d 0.0 c 0.0 c
LSD (0.05) 13.3 8.9 14.4 10.0 10.0 8.9

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed crop injury at scale of 0 to 100%; 0= no injury and 100% = plant death.

55

Table 23. The effect of postemergence flumioxazin on carrot yield, 2001, 2002, and 2003.

 

Yield (kg/1.5m ofbed) a

 

 

Rate Newaygo Oceana Oceana Newaygo Oceana
“came” (kg ai/ha) 992%)AT 992 (1)3111" 83%); 912 (153T 1025012;
Linuron 0.280 11.9 a 11.6 a 14.9 a
Linuron 0.561 10.6 ab 11.9 a 10.4 a 15.1 a 14.2 a
Linuron 1.121 16.5 a 14.8 a
Flumioxazin 0.035 8.7 b 11.0 a 4.9 b 15.6 a 16.6 a
Flumioxazin 0.053 8.9 b 10.9 a 5.7 b
Flumioxazin 0.071 11.6 a 3.7 b 13.0 a 17.2 a
Untreated 6.1 e 9.7 a 11.9 a 15.5 a 13.9 a
LSD (0,0,, 2.2 NS b 4.7 NS NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Carrots were planted on beds. Each bed had 3 rows
b No signiﬁcant difference

56

were considerably different; ﬂumioxazin signiﬁcantly reduced yield at Oceana. Even at a
low ﬂumioxazin rate of 0.035 kg/ha, yield was reduced to half compared to linuron 0.56
kg/ha. However, stand was not signiﬁcantly different compared to linuron and hand
weeded treatments. It is probable that crop yield reduction in 2002 was more inﬂuenced
by weed competition than by the effect of the herbicide itself. During 2002 there was
high precipitation and higher weed pressure. Crop injury at Oceana was also higher in
2002 and 2003 than in 2001 at 7 DAT (Table 22). Carrot injury with ﬂumioxazin at
0.035 kg/ha in muck soil was not different ﬂom linuron at 1.121 kg/ha. However,
ﬂumioxazin at 0.070 kg/ha increased injury in muck soil at the MSU Muck Farm in 2003
(Table 22)

F lumioxazin postemergence at 0.053 kg/ha had good control (> 95%) during the
season of redroot pigweed, ladysthumb, common purslane (Portulaca oleracea L.), and
common chickweed. Early in the season, ﬂumioxazin at 0.053 kg/ha gave good control
(> 77%) of large crabgrass (Digitaria sanguinalis L.) and common lambsquarters at
Newaygo in 2001 (Appendix 2). However, three weeks later control of large crabgrass
and common lambsquarters fell to less than 30% (Appendix 3). In 2003, ﬂumioxazin at
0.070 had good control (73%) of redroot pigweed and 83% control of common
lambsquarters at Newaygo County (Appendix 22). F lumioxazin at 0.035 kg/ha had a fair
control (> 60%) of large crabgrass and common lambsquarters 7 DAT and no control
three weeks after treatment. The addition of NIS 0.25% to ﬂumioxazin at 0.035 and
0.053 kg/ha in Newaygo County during 2001 increased weed control to above 95% for

all weeds described above (Appendix 2).

57

At the Oceana site, ﬂumioxazin at 0.035, 0.053 and 0.070 kg/ha had good control
(> 90%) of redroot pigweed during all the season in all three years (Appendixes 7, 15, 16,
17, 18, and 19). In 2001, ﬂumioxazin at 0.035, 0.053 and 0.070 kg/ha had good control
(> 90%) of shepherd's-purse, eastern black nightshade, common chickweed and common
lambsquarters; and 80% control of ladysthumb (Appendix 8). In 2002, ﬂumioxazin at
0.035, 0.053 and 0.070 kg/ha had fair to good control (< 80%) of common ragweed,
ladysthumb, and common lambsquarters; and good control of black medic. Control of
common ragweed and ladysthumb decreased during the season reaching a level of less
than 67% for common ragweed and less than 50% for ladysthumb (Appendixes 15, 16,
17, and 18). In 2003, ﬂumioxazin at 0.035 and 0.070 kg/ha had fair to good control (<
80%) of common lambsquarters and hairy nightshade (Solanum sarrachoides Sendtner)
and fair control (< 67%) of redroot pi gweed.

At the MSU Muck Farm on organic soil, ﬂumioxazin at 0.035 and 0.070 kg/ha
had poor control of yellow nutsedge (C yperus esculentus L.), ladysthumb, redroot
pigweed, common purslane, and common lambsquarters. Flumioxazin at 0.071 kg/ha

increased moderately control of redroot pi gweed and common purslane (Appendix 30).

F [ufenacet 24 % plus metribuzin 3 6% (Domain DF) preemergence:

Carrot was tolerant of Domain (ﬂufenaeet 24% plus metribuzin 36%)
preemergence at 0.336, 0.448, and 0.673 kg/ha in mineral soils in 2001, 2002, and 2003
at Newaygo and Oceana County (Tables 24, 25, and 26). At 0.336 kg/ha, crop injury,

stand counts, and yield did not differ ﬂom linuron in 2001 and 2002 at Newaygo and

58

Table 24. The effect of preemergence ﬂufenacet plus metribuzin on carrot stand, 2001, 2002, and 2003

 

Stand count (plants/1m of bed) b

 

 

Rate Oceana Oceana Newaygo Oceana
. 2001 2002 2003 2003

Treatment (kg ml“) 35 DAT 127 DAT 35 DAT 35 DAT
Linuron 0.280 26.7 a 257.0 a
Linuron 0.561 22.0 a 69.5 a 258.0 a 41.7 a
Domain a 0.336 23.0 a 64.7 a
Domain 0.448 109.0 b 30.3 b
Domain 0.673 73.0 b 30.0 b
Untreated 24.3 a 97.3 a 207.3 a 42.0 a
LSD (0,0,, NS c NS 94.3 10.1

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Domain: ﬂufenacet 24% plus metribuzin 36%

b Carrots were planted on beds. Each bed had 3 rows

c No signiﬁcant difference

59

Table 25. The effect of preemergence ﬂufenacet plus metribuzin on carrot injury, 2001, 2002, and 2003

 

 

 

Carrot injury (%) b
Rate Oceana Oceana Newaygo Oceana Muck Farm

. 2001 2002 2003 2003 2003
“came“ (kg “’1‘” 35 DAT 42 DAT 21 DAT 21 DAT 14 DAT
Linuron 0.280 0.0 a 3.3 b
Linuron 0.561 0.0 a 14.4 a 3.3 b 25.5 b
Linuron 1.121 18.9b
Domain 3 0.336 7.8 a 18.9 a
Domain 0.448 55.5 a 47.8 a
Domain 0.673 70 a 52.2 a 63.3 a
Untreated 7.8 a 0.0 a 14.4 b 0.0 c 11.1 b
LSD (005, NS ° NS 25.6 17.8 20.0

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Domain: ﬂufenacet 24% plus metribuzin 36%
b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death.

c No signiﬁcant difference

60

Table 26. The effect of preemergence ﬂufenacet plus metribuzin on carrot yield, 2001, 2002, and 2003.

 

Yield (kg/1.5m ofbed) b

 

 

Rate Oceana Oceana Newaygo Oceana

. 2001 2002 2003 2003
Tmmem “‘3 M“) 125 DAT 127 DAT 128 DAT 142 DAT
Linuron 0.280 14.6 a 19.1 a
Linuron 0.561 14.2 ab 7.0 b 18.5 a 16.5 a
Domain 3 0.336 11.8 be 6.2 b
Domain 0.448 14.6 a 14.1 a
Domain 0.673 15.1 a 12.8 a
Untreated 10.0 c 9.9 a 19.1 a 15.1 a
LSD (0,0,, 2.7 2.6 NS ° NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Domain: ﬂufenacet 24% plus metribuzin 36%
b Carrots were planted on beds. Each bed had 3 rows

0 No signiﬁcant difference

61

Oceana County. In 2003, at rates of 0.448 and 0.673 kg/ha, crop injury was higher than
linuron and stand count was lower than linuron in mineral and organic soils in all sites.

However, yield was not reduced and was not different ﬂom linuron application (Tables
24, 25, and 26).

Weed control with Domain at 0.336, 0.448, and 0.673 kg/ha was over 90% in all
sites and all years for common lambsquarters, redroot pigweed, shepherd's-purse,
common ragweed, ladysthumb, black medic, common chickweed, annual bluegrass (Poa
annua L.), common purslane, and mayweed chamomile (Anthemis cotula L.); with the
exception of ladysthumb with 83% control in 2002 at Oceana County and eastern black
nightshade with 87% in 2001 at Oceana County (Appendixes 8, 10, 20, 24, and 27). In
organic soil, control of yellow nutsedge was only 40% in 2003 at MSU Muck Farm

(Appendix 27).

Clomazone preemergence:

Carrot was tolerant of clomazone at 0.28 and 0.561 kg/ha. Crop injury, stand
counts and yield were not different ﬂom linuron at 0.561 kg/ha in mineral soil in 2002
and 2003 at Oceana and Newaygo counties (Tables 27, 28, and 29). In organic soil, crop
injury was not signiﬁcantly different from linuron in 2003 at MSU Muck Farm (Table
28). In mineral soil, clomazone at 1.121 kg/ha increased crop injury slightly but was not
signiﬁcantly different ﬂom linuron. However, yield was signiﬁcantly reduced compared
to linuron at 0.561 kg/ha but not signiﬁcantly different from the untreated control (Table

29).

62

Table 27. The effect of preemergence clomazone on carrot stand, 2002 and 2003.

 

Stand count (plants/1m of bed) a

 

 

Rate Oceana Oceana Newaygo
. . 2002 2003 2003

Treatment “‘3 am“) 127 DAT 35 DAT 35 DAT
Linuron 0.280 257.0 a
Linuron 0.561 69.5 a 41.7 a 258.0 a
Clomazone 0.280 77.0 a 35.3 a 222.7 a
Clomazone 0.561 36.0 a 250.0 a
Clomazone 1.121 33.3 a
Untreated 97.3 a 42.0 a 207.3 a
LSD (0.0,, NS b NS NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b . . .

No Slgnlﬁcant drfference

63

Table 28. The effect of preemergence clomazone on carrot injury, 2002 and 2003.

 

 

 

Carrot injury (%) a
Rate Oceana Oceana Newaygo Muck Farm

. 2002 ‘ 2003 2003 2003
Treatment (kg “/ha) 42 DAT 21 DAT 21 DAT 14 DAT
Linuron 0.280 3.3 a
Linuron 0.561 14.4 a 25.5 a 3.3 a
Linuron 1.121 18.9a
Clomazone 0.280 7.8 a 18.9 a 25.5 a 7.8 a
Clomazone 0.561 22.2 a 22.2 a 7.8 a
Clomazone 1.121 36.7 a
Untreated 0.0 a 0.0 b 14.4 a 11.1 a
LSD (0.0,, NS b 17.8 NS NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death
b No signiﬁcant difference

64

Table 29. The effect of preemergence clomazone on carrot yield.

 

Yield (Kg/1.5m ofbed) a

 

 

Rate Oceana Oceana Newaygo
. ‘ 2002 2003 2003

Treatment (kg am" 127 DAT 142 DAT 128 DAT
Linuron 0.280 19.1 a
Linuron 0.561 7.0 b 16.5 a 18.5 a
Clomazone 0.280 5.3 b 14.1 ab 18.3 a
Clomazone 0.561 14.2 ab 20.8 a
Clomazone 1.121 12.4 b
Untreated 9.9 a 15.1 ab 19.1 a
LSD mos, 2.6 4.0 NS b

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b . . .

No srgruﬁcant dlfference

65

Clomazone at 0.28 kg/ha controlled over 95% of ladysthumb, common
lambsquarters, common chickweed, annual bluegrass, and common purslane in all years
and all sites (Appendixes 10, 20, 24, and 27). In 2002, control of common ragweed and
black medic was less than 75% at Oceana County (Appendix 10). At an increased rate of
0.561 kg/ha, clomazone had a tendency to improve weed control but was not statistically

different.

Oxyﬂuorfen postemergence:

Carrot demonstrated moderate tolerance to postemergence oxyﬂuorfen at 0.035
and 0.071 kg/ha in 2001, 2002, and 2003 in mineral soil in Newaygo and Oceana County
(Tables 30, 31, and 32). In 2003, an additional rate of 0.14 kg/ha was included in the
studies increasing slightly the initial crop injury but not affecting yield. Yield and stand
count was not signiﬁcantly different compared to linuron 0.56 kg/ha in 2001 at Oceana
and Newaygo County. In 2002 in Oceana County, yield was signiﬁcantly reduced,
probably explained by weed competition more than an effect of oxyﬂuorfen activity
because initial visual crop injury was 14.4% and 1 1.1% for 0.035 and 0.070 kg/ha
respectively and stand counts were not different compared to linuron application. The
plots were not weeded after application and there was considerable weed pressure later in
the season. In 2003, yield was slightly reduced in Newaygo County at oxyﬂuorfen rates
of 0.035 and 0.070 kg/ha but yield was similar to linuron when oxyﬂuorfen was applied
at 0.140 kg/ha. This better yield can be explained by better weed control with the higher

oxyﬂuorfen rate. The same year in Oceana county yield was not different ﬂom linuron at

66

Table 30. The effect of postemergence oxyﬂuorfen on carrot stand, 2001 and 2002.

 

 

 

Stand count (plants/1m of bed) a
Rate Newaygo Oceana Oceana
. ‘ 2001 2001 2002

Treatment (kg M3) 99 DAT 99 DAT 84 DAT
Linuron 0.280 65.0 a 25.3 a
Linuron 0.561 63.0 a 24.7 a 92.3 a
Oxyﬂuorfen 0.035 73.7 a 24.7 a 89.7 a
Oxyﬂuorfen 0.071 82.3 a
Oxyﬂuorfen 0. 140
Untreated 59.0 a 23.0 a 101.0 a
LSD (00,, NS b NS NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b No signiﬁcant difference

67

Table 31. The effect of postemergence oxyﬂuorfen on carrot injury, 2001, 2002, and 2003

 

 

 

Carrot injury (%) a
Muck
Rate Newaygo Oceana Oceana Newaygo Oceana Farm
. 2001 2001 ‘ 2002 2003 2003 2003
Treatment (kg am) 7 DAT 7 DAT 7 DAT 14 DAT 14 DAT 14 DAT
Linuron 0.280 0.0 b 3.3 ab 3.3 d
Linuron 0.561 7.8 b 3.3 ab 3.3 ab 14.4 c 7.8 cd
Linuron 1.121 25.5 b 14.4 be 3.3 ab
Oxyﬂuorfen 0.035 47.8 a 11.1 a 14.4 a 25.5 b 22.2 ab 0.0 b
Oxyﬂuorfen 0.071 1 1.1 ab 30.0 ab 14.4 be 0.0 b
Oxyﬂuorfen 0.14 36.7 a 30.0 a 11.1 a
Untreated 0.0 b 0.0 b 0.0 b 0.0 d 0.0 d 0.0 b
LSD (0.051 13.3 8.9 14.4 11.1 11.1 8.9

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed crop injury at scale of 0 to 100%; 0= no injury and 100% = plant death.

68

Table 32. The effect of postemergence oxyﬂuorfen on carrot yield, 2001, 2002, and 2003

 

Yield (kg/1.5m ofbed) a

 

Rate Newaygo Oceana Oceana Newaygo Oceana
. 2001 2001 2002 2003 2003
Treatment “‘3 am“) 99 DAT 99 DAT 84 DAT 91 DAT 105 DAT

 

Linuron 0.280 11.9 a 11.6 a 14.9 a

Linuron 0.561 10.6 a 11.9 a 10.4 a 15.1 a 14.2 a
Linuron 1.121 16.5 a 14.8 a
Oxyﬂuorfen 0.035 10.4 a 12.0 a 3.2 b 8.5 be 15.5 a
Oxyﬂuorfen 0.071 3.3 b 7.9 c 15.7 a
Oxyﬂuorfen 0.14 12.0 ab 16.8 a
Untreated 6.1 b 9.7 a 11.9 a 15.5 a 13.9 a
LSD (0,0,, 2.0 NS b 4.7 3.7 NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at 0 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b No signiﬁcant difference

69

all oxyﬂuorfen rates (0.035, 0.070, and 0.140 kg/ha). For all experiments in mineral soil,
oxyﬂuorfen caused slightly more injury than regular application of linuron at 0.561 kg/ha
(Table 31). In organic soil, oxyﬂuorfen caused initially no carrot injury, similar to
linuron in 2003 at MSU Muck Farm (Table 31).

Oxyﬂuorfen provided good weed control in general as reported by Ghosheh in
2004. Oxyﬂuorfen at 0.035 kg/ha had good control (> 90%) of common lambsquarters,
redroot pi gweed, ladysthumb, and common purslane in 2001 at Oceana and Newaygo
County (Appendixes 2, 3, 7 and 8). Results in 2002 were inconsistent; in Oceana
County, control of redroot pigweed was 70% at 0.035 kg/ha and 97% at 0.070 kg/ha;
control of common ragweed and ladysthumb was less than 65%, control of common
lambsquarters was around 75%, and had good control (> 97%) of black medic and
common purslane (Appendixes 15 and 16). Weed control results in 2003 at Newaygo
County was less effective compared to the other years and sites. Control of redroot
pigweed and common lambsquarters went ﬂom a low 37% at 0.070 kg/ha to a high of
67% for redroot pigweed and 80% for common lambsquarters at 0.140 kg/ha of
oxyﬂuorfen (Appendix 22). The same year 2003, in Oceana County redroot pigweed
control was over 90% (Appendix 25). In organic soil at the MSU Muck Farm in 2003,
control of yellow nutsedge was poor, less than 37% for all three oxyﬂuorfen rates. For
the lower rate of 0.035 kg/ha control of ladysthumb, common purslane, and common
lambsquarters was partial between 53% and 87%. However, control of those weeds was

better at higher rates of oxyﬂuorfen (Appendix 30).

70

Mesotrione postemergence:

Carrot tolerance to mesotrione postemergence was inconsistent across different
sites and years. This disparity in results could be explained by the effect of temperature
and humidity on the activity of mesotrione on plants (Armel et. al., 2003 and Johnson et.
al., 2002a). Carrot stand count, Visual injury and yield with mesotrione postemergence
treatment at 0.011 kg/ha was not different ﬂom linuron in 2001 at Oceana County
(Tables 33, 34, and 35). In 2002, mesotrione postemergence rates were increased to
0.022 and 0.045 kg/ha at Oceana County. At both rates initial crop injury was higher
than linuron but 21 DAT there was minimal injury (Appendix 14). Stand counts for both
rates were not signiﬁcantly different ﬂom linuron. Carrot yield ﬂom mesotrione 0.045
kg/ha was not different ﬂom linuron 0.561 kg/ha. However, carrot treated with
mesotrione 0.022 kg/ha showed decreased yield, probably as a result of higher weed
competition at the end of the season (Table 35). Mesotrione at 0.022 kg/ha is far below
the recommended rate of 0.07 to 0.15 kg/ha for postemergence weed control (Grichar et.
al. 2003); this could explain the higher weed pressure at 0.022 kg/ha. In Oceana County
in 2003, crop injury was considerably higher than regular linuron treatment. Mesotrione
at 0.05 kg/ha caused 57% Visual injury and mesotrione at 0.105 caused 67% visual injury
compared to linuron visual injury of 17% (Table 34). However, crop yield with
mesotrione at 0.05 kg/ha was not statistically different ﬂom linuron yield. Mesotrione at
0.105 kg/ha reduced yield signiﬁcantly (Table 35). A similar result of initial high level of
injury but with no effect on yield was reported on corn (Johnson et. al., 2002b). In
Newaygo County in 2003, mesotrione postemergence at 0.05 and 0.105 kg/ha caused

high crop injury and reduced crop yield signiﬁcantly (Tables 34 and 35). In

71

Table 33. The effect of postemergence mesotrione on carrot stand, 2001 and 2002

 

Stand count (plants/1m of bed) a

 

 

Rate Oceana Oceana
Treatment (kg ai/ha) 99223;]. 83032.1.
Linuron 0.280 25.3 a
Linuron 0.561 24.7 a 92.3 a
Linuron 1.121
Mesotrione 0.01 1 22.3 a
Mesotrione 0.022 83.7 a
Mesotrione 0.045 93.0 a
Mesotrione 0.050
Mesotrione 0. 1 05
Untreated 23.0 a 101.0 a
LSD (00,, NS b Ns

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b No signiﬁcant difference

72

Table 34. The effect of postemergence mesotrione on carrot injury, 2001 , 2002, and 2003.

 

 

 

Carrot injury (%) a
Rate Oceana Oceana Newaygo Oceana Muck Farm

. 2001 ‘ 2002 2003 2003 2003
Treatment (kg am) 7 DAT 7 DAT l4 DAT 14 DAT 14 DAT
Linuron 0.280 3.3 a 3.3 d
Linuron 0.561 3.3 a 3.3 b 14.4 c 7.8 cd
Linuron 1.121 25.5 b 14.4 c 3.3 c
Mesotrione 0.011 7.8 a
Mesotrione 0.022 25.5 a
Mesotrione 0.045 30.0 a
Mesotrione 0.050 70.0 a 52.2 b 74.4 b
Mesotrione 0.105 66.7 a 63.3 a 88.9 a
Untreated 0.0 a 0.0 b 0.0 d 0.0 d 0.0 c
LSD (0.0,, NS b 14.4 11.1 11.1 8.9

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed crop injury at scale of 0 to 100%; 0= no injury and 100% = plant death.
b No signiﬁcant difference

73

Table 35. The effect of postemergence mesotrione on carrot yield, 2001, 2002, and 2003.

 

Yield (Kg/1.5m ofbed) a

 

 

Rate Oceana Oceana Newaygo Oceana
Treatment (kg aim") 9§§AT 83(1)::T 912(1):; 102503;
Linuron 0.280 11.6 a 14.9 a
Linuron 0.561 11.9 a 10.4 ab 15.1 a 14.2 ab
Linuron 1.121 16.5 a 14.8 a
Mesotrione 0.011 1 1.2 a
Mesotrione 0.022 4.2 c
Mesotrione 0.045 6.2 bc
Mesotrione 0.050 5.6 b 11.0 be
Mesotrione 0.105 7.2 b 10.5 c
Untreated 9.7 a 11.9 a 15.5 a 13.9 abc
LSD (00,, NS b 4.7 3.7 3.7

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b No signiﬁcant difference

74

organic soil in 2003 at MSU Muck Farm, the crop injury was high reaching a visual

rating of 88.9% or more compared to 3.3% from linuron application (Table 34).

Fl ufenacet preemergen ce:

Carrot demonstrated tolerance to ﬂufenacet preemergence at 0.336 and 0.673
kg/ha, although injury was higher at 0.673 kg/ha. Crop yield was not different ﬂom
regular linuron treatment in 2001 and 2003 in Oceana and Newaygo County (Table 38).
However, crop yield was lower than linuron in 2002. Initial crop injury was not
signiﬁcantly different ﬂom linuron but ﬂufenacet injury continued during the season
whereas linuron injury almost disappeared by the end of the season (Appendix 23). In
addition, this reduced yield can also be explained by a higher weed competition due to
the poor control of ladysthumb (27%) and redroot pigweed with 37% control

(Appendixes 9 and 10).

Metribuzin preemergence:

Metribuzin preemergence was only studied in 2003 in the three Sites. Metribuzin
at 0.42 kg/ha demonstrated partial safety for carrot. Initial visual injury at Newaygo
County was 77% and at Oceana was 40% whereas linuron at 0.561 kg/ha was 13% and
33% respectively. Crop yields were not statistically different ﬂom linuron in both sites
but presented a tendency to be lower (Table 39). In organic soil, metribuzin applied at
0.561 kg/ha showed toxicity for carrot with a visual rate of 60%. For all three sites,

metribuzin had a good weed control (> 90%) comparable with the results obtained by

75

Table 36. The effect of preemergence ﬂufenacet on carrot stand, 2001, 2002, and 2003.

 

Stand count (plants/1m of bed) a

 

 

Rate Oceana Oceana Newaygo Oceana
. 2001 ’ 2002 2003 2003

Treatment (kg ma) 35 DAT 127 DAT 35 DAT 35 DAT
Linuron 0.280 26.7 a 257.0 a
Linuron 0.561 22.0 b 69.5 ab 258.0 a 41.7 a
Flufenacet 0.336 24.0 ab 51.0 b
Flufenacet 0.673 148.3 b 30.7 b
Untreated 24.3 ab 97.3 a 207.3 ab 42.0 a
LSD (0.05, 4.1 35.3 94.3 10.1

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows

76

Table 37. The effect of preemergence ﬂufenacet on carrot injury, 2001, 2002, and 2003.

 

 

 

Carrot injury (%) a
Rate Oceana Oceana Newaygo Oceana Muck Farm
. 2001 ‘ 2002 2003 2003 2003
Treatment (kg M“) 35 DAT 42 DAT 21 DAT 21 DAT 14 DAT
Linuron 0.280 0.0 b 3.3 a
Linuron 0.561 0.0 b 14.4 a 3.3 a 25.5 a
Linuron 1.121 18.9a
Flufenacet 0.336 14.4 a 7.8 a
Flufenacet 0.673 25.5 a 33.3 a 25.5 a
Untreated 7.8 ab 0.0 a 14.4 a 0.0 b 11.1 a
LSD W, 13.3 NS b NS 17.8 NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed crop injury at scale of 0 to 100%; 0= no injury and 100% = plant death.
b No signiﬁcant difference

77

Table 38. The effect of preemergence ﬂufenacet on carrot yield, 2001, 2002, and 2003.

 

Yield (Kg/1.5m ofbed) a

 

 

Rate Oceana Oceana Newaygo Oceana
. 2001 2002 2003 2003

Trea'mem (kg ”113) 125 DAT 127 DAT 128 DAT 142 DAT
Linuron 0.280 14.6 a 19.1 a
Linuron 0.561 14.2 a 7.0 b 18.5 a 16.5 a
Linuron 1.121
Flufenacet 0.336 12.7 ab 1.0 c
Flufenacet 0.673 17.4 a 13.8 a
Untreated 10.0 b 9.9 a 19.1 a 15.1 a
LSD (0.0,, 2.7 2.6 Ns b NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Carrots were planted on beds. Each bed had 3 rows

b No signiﬁcant difference

78

Table 39. The effect of preemergence metribuzin on carrot stand, injury, and yield.

 

 

 

 

 

 

Stand count Crop injury b
plants/1m of bed a (%) kg/1.5m of bed

Rate Newaygo Oceana Newaygo Oceana 11:11:: Newaygo Oceana
Treatment (kg ai/ha) 2003 2003 12003 2003 2003 2003 2003
Linuron 0.280 257.0 a 3.3 b 19.1 a
Linuron 0.561 258.0 a 41.7 a 3.3 b 25.5 a 18.5 a 16.5 a
Linuron 1.121 18.9b
Metribuzin 0.420 66.3 b 38.3 a 74.4 a 33.3 a 15.0 a 14.9 a
Metribuzin 0.561 55.5 a
Untreated 207.3 a 42.0 a 14.4 b 0.0 b 11.1 b 19.1 a 15.1 a
LSD (0.0,, 94.3 Ns ° 24.4 17.8 22.2 NS Ns

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Carrots were planted on beds. Each bed had 3 rows
b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death.

c No signiﬁcant difference

79

Table 40. The effect of preemergence s-metolachlor, pendimethalin, and sulfentrazone on carrot stand,
injury, and yield.

 

 

 

 

 

 

Stand count Carrot injury b Yield
plants/1m of bed a (%) kg/l .5m ofbed
Rate Oceana Oceana , Oceana Oceana Muck Oceana Oceana

Treatment kg ai/ha 2001 2002 2001 2002 2003 2001 2002
Linuron 0.280 26.7 a 0.0 b 14.6 a
Linuron 0.561 22.0 b 69.5 ab 0.0 b 14.4 b 14.2 ab 7.0 b
Linuron 1.121 18.9a
S-metolachlor 0.561 24.3 ab 43.3 be 7.8 b 3.3 b 11.8 be 2.2 c
S-metolachlor 1.9 11.1 a
Pendimethalin 0.841 23.7 ab 52.3 be 11.1 b 3.3 b 12.3 abc 0.9 c
Pendimethalin 2.24 11.1 a
Sulfentrazone 0.112 17.0 c 27.0 c 33.3 a 52.2 a 11.9 abc 0.7 c
Untreated 24.3 a 97.3 a 7.8 b 0.0 b 11.1 a 10.0 c 9.9 a
LSD (0,0,, 4.1 35.3 13.3 24.4 NS ° 2.7 2.6

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows

b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death.

6 No signiﬁcant difference

80

Table 41. The effect of preemergence mesotrione on carrot stand, injury, and yield.

 

 

 

 

 

 

Stand count Carrot injury b Yield
plants/1m of bed a (%) kg/1.5m ofbed
Rate Newaygo Oceana Newaygo Oceana Muck Newaygo Oceana

Treatment kg ai/ha 2003 2003 2003 2003 2003 2003 2003
Linuron 0.280 257.0 a 3.3 b 25.5 b 19.1 a 16.5 a
Linuron 0.561 258.0 a 41.7 a 3.3 b 18.5 a
Linuron 1.121 18.9b
Mesotrione 0.112 0.0 b 1.0 b 100.0 a 100.0 a 88.9 a 0.0 b 5.0 b
Mesotrione 0.224 0.0 b 0.0 b 100.0 a 100.0 a 96.7 a 0.0 b 1.0 c
Mesotrione 0.448 0.0 b 100.0 a 100.0 a 0.0 c
Untreated 207.3 a 42.0 a 14.4 b 0.0 c 11.1 b 19.1 a 15.1 a
LSD (005, 94.3 10.1 24.4 17.8 22.2 4.8 4.0

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Carrots were planted on beds. Each bed had 3 rows
b Visually assessed crop injury at scale of 0 to 100%; 0: no injury and 100% = plant death..

81

Ghosheh (2004) with the exception of yellow nutsedge in organic soil that reached a

control of only 57%.

Other results:

S-metolachlor preemergence at 0.561 kg/ha did not reduce carrot emergence in
2001 but did reduce carrot emergence in 2002 at Oceana County. Crop injury was
similar to linuron in mineral and organic soil. Yield was not different ﬂom linuron at
0.561 kg/ha in 2001. However, yield was signiﬁcantly lower than linuron in 2002 at
Oceana County (Table 40). Pendimethalin preemergence at 0.841 kg/ha gave results
similar to linuron in stand counts and initial crop injury in 2001 and 2002 at Oceana
County. Carrot yield was similar to linuron in 2001 but was signiﬁcantly reduced in
2002; however, weed pressure was higher in 2002 than in 2001. Pendimethalin at 2.24
kg/ha in organic soil caused the same level of crop injury as linuron at 1.121 kg/ha (Table
40). Mesotrione preemergence at 0.112, 0.224, and 0.448 killed the carrot in organic and
mineral soil (Table 41).

In preemergence weed control, Domain (ﬂufenacet 24% plus metribuzin 36%)
and clomazone did not injure carrot. Domain at 0.336, 0.448, and 0.673 kg/ha did not
injure carrot and had good control of common lambsquarters, redroot pi gweed,
shepherd’s-muse, common ragweed, ladysthumb, black medic, common chickweed,
annual bluegrass, common purslane, mayweed chamomile, and eastern black nightshade.
Clomazone at 0.28 and 0.561 kg/ha did not injure carrot and had good control of
ladysthumb, common lambsquarters, common chickweed, annual bluegrass, and common

purslane. In postemergence weed control, oxyﬂuorfen at 0.035, 0.070 and 0.140 kg/ha

82

caused some foliar injury, but did not reduce yield of carrot. Oxyﬂuorfen gave good
postemergence weed control but did not have residual activity, so weeds re-grew quickly

and carrot yield were reduced.

83

Literature Cited

Armel, G. R., H. P. Wilson, R. J. Richardson, and T. E. Hines. 2003. Mesotrione,
acetochlor, and atrazine for weed management in corn (Zea mays). Weed
Technology 171284—290

Bell, C. E., B. E. Boutwell, E. J. Ogbuchiekwe, and M. E. McGiffen, Jr. 2000a. Weed
control in carrots: efﬁcacy and economic value of linuron. HortScience 35 (6):
1089-1091

Bell, C. E., S. A. Fennimore, M. E. McGiffen, Jr., W. T. Lanini, D. W. Monks, J. B.
Masiunas, A. R. Bonanno, B. H. Zandstra, K. Umeda, W. M. Stall, R. R.
Bellinder, R. D. William, and R. B. McReynolds. 2000b. My View. Weed Science
48:1

Bellinder, R. R., J. J. Kirkwyland, and R. W. Wallace. 1997. Carrot (Daucus carota) and
Weed response to linuron and metribuzin applied at different crop stages. Weed
Technology 11: 23 5—240

Beuret, E. 1989. A new problem of herbicide resistance: Senecio vulgaris L. in carrot
crops treated with linuron. Revue-Suisse-de-Viticulture,-d'Arboriculture-et-
d'Horticulture 21 (6): 349-3 52

Brown D. and J. Masiunas. 2002. Evaluation of herbicides for pumpkin (Cucurbita spp.).
Weed Technology 162282—292

Cavero J ., J. Aibar, M. Gutierrez, S. Femandez-Cavada, J. M. Sopeﬁa, A. Pardo, M. L.
Suso, and C. Zaragoza. 2001. Tolerance of direct-seeded paprika pepper

(Capsicum annuum) to clomazone applied preemergence. Weed Technology
15:30—35

Crop Life Foundation. 1997. National pesticide use database.
http://cipm.nesu.edu/croplife

Diehl, H. J. and W. Benz. 1998. FOE 5043 (ﬂufenacet) and mixing partners for use in
maize, cereals, and potatoes in Germany. Pﬂanzenschutz-Nachrichten Bayer 51
(2) 129-138

Ghosheh, H. Z. 2004. Single herbicide treatments for control of broadleaved weeds in
onion (Alliurn cepa). Crop Protection 23: 53 9—542

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Gianessi, L. P. and M. B. Marcelli. 2000. Pesticide use in US. crop production: 1997.
National Center for Food and Agricultural Policy.
http://cipm.ncsu.edu/croplife/nationalsummaryl997.pdf

Grichar W. J ., B. A. Besler, K. D. Brewer and D. T. Palrang. 2003. Flufenacet and
metribuzin combinations for weed control and corn (Zea mays) tolerance. Weed
Technology 17:346—351

Haar, M. J ., S. A. Fennimore, M. E. McGiffen, W. T. Lanini, and C. E. Bell. 2002.
Evaluation of preemergence herbicides in vegetables crops. HortTechnology 12
(1): 95-99

Jensen, K. I. N., D. J. Doohan, and E. G. Specht. 2004. Response of processing carrot to
metribuzin on mineral soils in Nova Scotia. Canadian Journal of Plant Science 84:
669—676

Johnson B. C. and B. G. Young. 2002a. Inﬂuence of temperature and relative humidity
on the foliar activity of mesotrione. Weed Science 50:157—161

Johnson B. C., B. G. Young, and J. L. Matthew. 2002b. effect of postemergence
application rate and timing of mesotrione on corn (Zea mays) response and weed
control. Weed Technology 162414—420

Kuratle H. and E. M. Rahn. 1968. Weed control with linuron and prometryne. Journal
American Society for Horticultural Science 92: 465-472

Li, B. and A. R. Watkinson. 2000. Competition along a nutrient gradient: a case study
with Daucus carota and Chenopodium album. Ecological Research 15: 293-306

Masabni, J. G. and B. H. Zandstra. 1999. Discovery of a common purslane (Portulaca
oleracea) biotype resistant to linuron. Weed Technology 13 (3): 599—605.

Michigan State University. 2000. A strategic plan for the Michigan carrot industry.
Workshop Summary. hip://pestdata.ncsu.edemsp/pdf/micmots.@

Mitchell, G., D. W. Bartlett, T. EM. Fraser, T. R. Hawkes, D. C. Holt, J. K. Townson,
and R. A. Wichert. 2001. Mesotrione: a new selective herbicide for use in maize.

Pest Management Science 57:120-128

Ogbuchiekwe, E. J ., M. E. McGiffen, Jr., J. Nuﬁez, and S. A. Fennimore. 2004.
Tolerance of carrot to low-rate preemergent and postemergent herbicides.
HortScience 39 (2): 291-296

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Peachey, R. E. and C. Mallory-Smith. Tolerance of processed vegetables to herbicides.
Oregon State University. http://oregonstate.edu/dept/hort/weedmt/screen2.htrn

Putnam, A. R. 1990. Vegetable weed control with minimal herbicide input. HortScience
25 (2): 155-159

Ross, M. A. and C. A. Lembi. 1985. Applied weed science. Macmillan Publishing
Company. New York. 340 p.

Stall, W. M. 2003. Weed control in carrots. University of Florida. Fact Sheet HS-201,
http://edis.ifas.uﬂ.edu/pdfﬁles/WG/WG02600.Ddf

US. Department of Agriculture. 1999. Crop proﬁle for carrots in michigan.
http://www.ipmcenters.org/cropproﬁles/docs/micarrotshtml

US. Department of Agriculture. 2002. Census of agriculture. National Agricultural
Statistics System

United States Environmental Protection Agency. 1995. Linuron. R.E.D. Facts, EPA-738-
F-95-003

United States Environmental Protection Agency. 1998. Metribuzin. R.E.D. Facts, EPA-
73 8-F-96-006. http://www.epa.gov/onpsrrdl/RED3/factsheets/0181faet.pdf

United States Environmental Protection Agency. 2001. Mesotrione. R.E.D. Facts, EPA-
738-F-95-003

Zandstra, B. 2005. Weed control guide for vegetable crops. East Lansing, Michigan,
Michigan State University. Extension Bulletin E 433

Zhang, J ., S. E. Weaver, and A. S. Hamill. 2000. Risk and reliability of using herbicides
at below-labeled rates. Weed Technology 14: 106-115

86

CHAPTER III
COMPARISON OF A ROTARY ATOMIZER “PROPTEC” AND CONVENTIONAL

SPRAYER FOR HERBICIDE APPLICATION IN CARROTS.

Introduction

Applying linuron at reduced rates may be an alternative method to reduce total
pesticide application and still maintain good weed control. Zhang et a1 (2000) reported
variable results in weed control when below-labeled rates were used. Weed control
efficacy for below-labeled rates in several studies was lower than for labeled rates when
below-labeled rates were not used in conjunction with other weed control methods such
as cultivation. However, Zhang found that weed control was 80% or higher in 50% of
the studies. In general terms, weed control tended to be lower and more variable at
reduced rates than at labeled rates but always remained within the 60 to 100% range. In
a study using linuron at below-label rates, Bellinder et al (1997) reported that linuron
postemergence at 0.14 and 0.28 kg/ha did not adequately control redroot pigweed
(Amaranthus retroﬂexus L.) and common lambsquarters (Chenopodium album L.). In
general terms, Bellinder found that below-label rate linuron resulted in 35% less control
than linuron at labeled rates. Putnam (1990) indicated that herbicide label rates are based
on averages produced by scientists’ research, where the herbicide is expected to be
effective most of the time. There is a window of opportunity for below-labeled rates

depending on the weed pressure and the application efﬁciency.

87

Zhang et al (2000) indicated that the use of adjuvants is not sufﬁciently reliable to
improve efficacy of below-label rate herbicides. However, more uniform coverage
through a more efﬁcient sprayer may improve herbicide foliar absorption and
effectiveness.

It may be possible to increase the effectiveness of postemergence herbicides
applied at reduced rates by increasing the herbicide contact area on the leaf surface.
Droplets ﬂom conventional nozzles tend to be large and variable in size (Ledebuhr et al,
1985). This variability in droplet size creates an inefficient deposition and runoff of the
pesticide, especially when large droplets are present. Small droplets tend to stick more
easily to the leaf surface (Landers et a1, 2000). Under normal application conditions,
some pesticide solution runs off the leaves and is lost. In other words, the amount of
chemical absorbed by the weeds is less than the amount applied. Increasing the
efﬁciency of deposition may allow for decreasing the total amount of herbicide required
to obtain good weed control.

A rotary atomizer (Proptec) was developed by engineers in the Michigan State
University Agricultural Engineering Department. In a rotary atomizer, liquid is fed into a
high-speed rotating screen cage. The impact and centrifugal forces pulverize the drops
and produce a very uniform spectrum of small drOplets (averaging 60 to 120 microns).
Approximately 95% of the droplets are the same size (Van Ee et al, 2000). Droplets are
directed to the crop by a small propeller producing highly turbulent and high volume
airﬂow while reducing driﬁ (Hanson et al, 2000; Landers et al, 2000). The airﬂow is

aimed deep into the crop canopy to reach weeds below the crop canopy.

88

In addition to improved penetration into the plant canopy, the small droplets
produced by the Proptec cover more foliage surface than bigger droplets with the same
total volume of spray mix. For the same volume of liquid, decreasing in half the diameter
of a droplet increases the number of droplets by eight. If the spray droplet diameter
decreases to a quarter of the original diameter, then the number of spray droplets
increases to 64. The area covered for a ﬁxed volume of liquid is doubled each time the
diameter of the droplet is halved (Landers et al, 2001).

The use of an air-assisted rotary atomizer applicator may improve the application
of postemergence herbicide in carrot ﬁelds. This experiment was conducted to compare
an air-assisted rotary atomizer Sprayer with a conventional boom sprayer for low volume

and reduced rate application of linuron on carrot.

Materials and Methods

A ﬁeld study was conducted at the MSU Muck Research Farm (Muck Farm) in
Laingsburg in 2001 to evaluate carrot tolerance and weed control with below-labeled
rates of linuron applied with a conventional boom sprayer and an air-assisted rotary
atomizer applicator. Soil type at the Muck Farm was a Houghton Muck soil with 80%
organic matter and soil pH of 6.3.

Field preparation, seed density, and fertilization, used in this study were typical
commercial practices. Carrot seeds of the cultivar ‘Premium’ were sown in three lines
per bed with a commercial carrot planter on June 13, 2001. Plot size was 3.2 m wide (2

beds) by 15 m long. Three factors were considered in this study: one, the effect of the

89

linuron postemergence rate; two, the effect of using an adjuvant; and three, the effect of
the type of sprayer. The treatments applied in this study are listed in detail in Table 42.

The spraying equipment consisted of a conventional boom sprayer and an air-
assisted rotary atomizer (Proptec) designed and constructed by Michigan State University
Agricultural Engineering Department. Both applicators were mounted on the same
tractor, one on each side. The conventional sprayer was a C02 pressurized boom sprayer
equipped with eight FF 1 1002 nozzles delivering 187 tha at a pressure of 207 kPa; 75
cm height, and a speed of 5.5 km/h. The air-assisted applicator was a rotary atomizer
with two sets of propellers delivering 46.7 L/ha and a ground speed of 5.5 km/h.
Treatments were applied postemergence on July 10 when carrots were 15 to 20 cm high.
Weeds present at the time of application were few large crabgrass (Digitaria sanguinalis
L.), few common purslane (Portulaca oleracea L.), and moderate yellow nutsedge
(Cyperus esculentus L.).

Visual crop injury and weed control were rated on July 30. Visual crop injury and
weed control estimates were done in a scale of 1 to 10, where 1 represented no injury and
10 represented complete plant death. Yields were collected on October 2 by harvesting
1.5 m of the center section of each plot. Fresh weight of carrot roots was recorded. The
experiment was repeated in 2002, but improper adjustment of the air-assisted sprayer
resulted in inadequate results.

Experiments were arranged in a split-block randomized complete block design
with four replications. Linuron rate were establish as the main blocks, and the subplots
were the sprayer type and the usage or not of adjuvant. Data ﬂom each experiment were

subjected to analysis of variance using SAS program (SAS, 1990).

90

Table 42. List of treatments applied at the MSU Muck Farm during 2001

 

 

 

 

Rate

Factors (kg ai/ha)
Linuron rate

Linuron 0.11

Linuron 0.22

Linuron 0.45
Sprayer

Conventional boom

Proptec
Adjuvant

Sylgard 309 + 0.5%

No Sylgard 309

 

91

Results and Discussion

The three-factor interaction effect, linuron rate, adjuvant application, and sprayer
type, was not signiﬁcant for any of the parameters assessed (Tables 43, 44, 45). The two
factor interactions: linuron rate x adjuvant, adjuvant x sprayer, and linuron rate x
sprayer, also were not signiﬁcant. No interaction was found in any combination of the
three factors studied when assessing the effect of the treatments on carrot injury, carrot
yield, and yellow nutsedge control.

The main effect of linuron rate on carrot injury, carrot yield, and yellow nutsedge
was not signiﬁcant (Table 46). Linuron at 0.11, 0.22, and 0.45 kg/ha alone or mixed with
Sylgard 309 (0.5%) gave similar low level of injury to carrots. These results are similar
to results obtained by Bellinder et al (1997) and Kuratle et al (1968), where they found
carrot tolerance to linuron up to 3.9 kg/ha. No difference was found when evaluating the
main effect of the adjuvant. The air-assisted rotary atomizer gave similar result to the
conventional boom.

Carrot yield was reduced only in the treatment with linuron at 0.22 kg/ha applied
with Proptec (Table 47). No other treatment had signiﬁcant yield reduction. This may be
explained by an uneven distribution of the weed population. Weed control analysis was
limited because of the general low weed population. Yellow nutsedge was the only weed
present at densities where weed control could be evaluated. The lowest yellow nutsedge
control was obtained by linuron at 0.22 kg/ha mixed with Sylgard 309, applied by
Proptec. However, it is important to mention that the nutsedge population was moderate

and with an uneven distribution.

92

Table 43. Analysis of variance of carrot injury, Proptec experiment

 

 

Source of Variation DF Sum of Squares Mean Square F Sig.
Total 47 10.479
Block 3 1.063 0.354
Linuron 2 0.042 0.021 0.040 NS 3
Error 1 6 3.125 0.521
Adjuvant 1 0.188 0.188 0.771 NS
Linuron x adjuvant 2 0.375 0.188 0.771 NS
Error 2 9 2.188 0.243
Sprayer 1 0.021 0.021 0.130 NS
Linuron x sprayer 2 0.292 0.146 0.913 NS
Adjuvant x sprayer 1 0.021 0.021 0.130 NS
Linuron x adjuvant x sprayer 2 0.292 0.146 0.913 NS
Error3 18 2.875 0.160

 

a Not Signiﬁcant at a = 0.05

93

Table 44. Analysis of variance of yellow nutsedge control, Proptec experiment

 

 

Source of Variation DF Sum of Squares Mean Square F Sig.
Total 47 330.000
Block 3 216.000 72.000
Linuron 2 18.500 9.250 1.762 NS 3
Error 1 6 31.500 5.250
Adjuvant 1 4.083 4.083 0.717 NS
Linuron x adjuvant 2 2.667 1.333 0.234 NS
Error 2 9 51.250 5.694
Sprayer 1 0.000 0.000 0.000 NS
Linuron x sprayer 2 0.500 0.250 1.059 NS
Adjuvant x sprayer 1 0.083 0.083 0.353 NS
Linuron x adjuvant x sprayer 2 1.167 0.583 2.471 NS
Error 3 18 4.250 0.236

 

a Not Signiﬁcant at a = 0.05

94

Table 45. Analysis of variance of carrot ﬂesh weight, Proptec experiment

 

 

Source of Variation DF Sum of Squares Mean Square F Sig.
Total 47 2084.581
Block 3 1902.514 634.171
Linuron 2 13.090 6.545 1.136 NS 3
Error 1 6 34.571 5.762
Adjuvant 1 11.175 1 1.175 1.924 NS
Linuron x adjuvant 2 7.949 3.974 0.684 NS
Error 2 9 52.273 5.808
Sprayer 1 1.920 1.920 0.693 NS
Linuron x sprayer 2 3.140 1.570 0.567 NS
Adjuvant x sprayer 1 3.183 3.183 1.149 NS
Linuron x adjuvant x sprayer 2 4.885 2.443 0.881 NS
Error3 18 49.881 2.771

 

a Not Signiﬁcant at a = 0.05

95

Table 46. AOV main effect of linuron rate, adjuvant use, and sprayer type factors independently of each
other on carrot injury, yield, and yellow nutsedge control, Proptec experiment.

 

 

 

Rate Crop injury 3 Yield CYPES control °
Treatment kg ai/ha scale 1-10 kg/l .5m ofbed b (scale 1-10)
Linuron rate effect
Linuron 0.11 1.25 a 16.25 a 7.63 a
Linuron 0.22 1.19 a 14.97 a 7.50 a
Linuron 0.45 1.25 a 15.55 a 8.88 a
LSD (0,05, 0.62 2.08 1.98
Adjuvant effect
Sylgard 309 0.5% 1.29 a 16.07 a 7.71 a
Sylgard 309 0.0% 1.17 a 15.11 a 8.29 a
LSD (0,05, 0.32 1.57 1.56
Sprayer effect
Conventional boom 1.21 a 15.79 a 8.00 a
Proptec 1.25 a 15.39 a 8.00 a
LSD (00,, NS d _ NS NS

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed crop injury at scale of l to 10; I: no injury and 10 == plant death.

b Carrots were planted on beds. Each bed had 3 rows

c Visually assessed weed control at scale of 1 to 10; 1: no control and 10 = complete control.

d Not Signiﬁcant at a = 0.05

96

Table 47. AOV means effect of linuron rate, adjuvant use, and sprayer type factors on carrot injury, yield,

and yellow nutsedge control

 

Rate Sprayer

Treatment (kg ai/ha) Equipment

Crop injury a
(scale 1-10)

Yield

CYPES
control c

kg/1.5m ofbedb (scale 1-101

 

Linuron + Sylgard 309 0.11 + 0.5% Boom

Linuron + Sylgard 309 0.11 + 0.5% Proptec
Linuron 0.1 1 Boom

Linuron 0.1 1 Proptec
Linuron + Sylgard 309 0.22 + 0.5% Boom
Linuron + Sylgard 309 0.22 + 0.5% Proptec
Linuron 0.22 Boom

Linuron 0.22 Proptec
Linuron + Sylgard 309 0.45 + 0.5% Boom

Linuron + Sylgard 309 0.45 + 0.5% Proptec

Linuron 0.45 Boom
Linuron 0.45 Proptec
LSD (0.051

1.25 a
1.50 a
1.00 a
1.25 a
1.25 a
1.00a
1.25 a
1.25 a
1.25 a
1.50 a
1.25 a
1.00 a

NSd

17.11 a
16.05 ab
15.08 abc
16.78 ab
16.30 ab
15.73 abc
14.35 be
13.52 c
16.19 ab
15.07 abc
15.73 abc
15.2 abc

2.473

7.25 d
7.75 cd
7.75 cd
7.75 cd
7.25 d
6.50 e
8.00 c
8.25 be
8.75 ab
8.75 ab
9.00 a
9.00 a

0.722

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed crop injury at scale of 1 to 10; 1: no injury and 10 = plant death.

b Carrots were planted on beds. Each bed had 3 rows

c Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = complete control.

d Not Signiﬁcant at a = 0.05

97

This study was not able to ﬁnd differences in herbicide application effectiveness
between the conventional sprayer and the Proptec. However, it is important to mention
that for similar application effectiveness, the Proptec uses a fourth of the amount of liquid
compared to the conventional sprayer. This lower requirement of water carrier could be

an advantage of less ﬂequent reﬁll trips required.

98

Literature Cited

Bellinder, R. R., J. J. Kirkwyland, and R. W. Wallace. 1997. Carrot (Daucus carota) and
weed response to linuron and metribuzin applied at different crop stages. Weed
Technology 11: 235—240

Hanson, E., J. Hancock, D. Ramsdell, A. Schilder, G. Van Be, and R. Ledebuhr. 2000.
Sprayer type and pruning affect the incidence of blueberry ﬂuit rots. HortScience
35 (2): 235-238.

Kuratle H. and E. M. Rahn. 1968. Weed control with linuron and prometryne. Journal
’ American Society for Horticultural Science 92: 465-472

Landers, A. and W. Wilcox. 2001. The effect of spray application in vineyards. Mark
Chien's Viticulture Newsletter, Penn State University (5/4/01).

Landers, A., W. Wilcox, G. English-Loeb, T. Martinson, and R. Dunst. 2000. Evaluation
of a controlled droplet sprayer to control disease and insects on grapes in New
York. A report to the Viticultural Consortium, Cornell University (1/21/00)

Ledebuhr, R., G. Van Ee, R. Resmer, T. Forbush, and H. Potter. 1985. Field comparison
of the effectiveness of air assisted rotary atomizers vs. conventional hydraulic
nozzles for disease control and vine kill in potatoes. American Society of
Agricultural Engineers. Paper No. 85-1076

Putnam, A. R. 1990. Vegetable weed control with minimal herbicide inputs. HortScience
25(2): 155-158

Van Ee, G., R. Ledebuhr, E. Hanson, J. Hancock, and DC. Ramsdell. 2000. Canopy
development and spray deposition in hi ghbush blueberry. HortTechnology
10:353-359.

Zhang, J ., S. E. Weaver, and A. S. Hamill. 2000. Risk and reliability of using herbicides
at below-labeled rates. Weed Technology 14: 106-115

99

CHAPTER IV

FLAME WEEDING EFFECTS ON SEVERAL WEED SPECIES

Introduction

F lame weeding is the most common thermal weed control method in agriculture
(Ascard, 1995b). This technique uses liqueﬁed petroleum gas (LPG) burners to generate
combustion temperatures of up to 1900 degrees Celsius, raising the temperature of the
exposed leaves very rapidly without requiring burning the weeds to cause death (Ascard,
1995b). This heat exposure denaturizes plant proteins, which results in loss of cell
function, causes intracellular water expansion, cell membrane rupture, and ﬁnally
desiccates and kills the weeds, normally within 2 to 3 days (Campbell, 2004; Diver,
2002; Heiniger, 1999; Rahkonen, 2003;). After its almost complete disappearance in the
19703, ﬂame weeding is starting to regain interest, mainly in Europe for non-selective
weed control in organic production (Ascard, 1995b).

The main advantages of ﬂame weeding are the lack of chemical residues
remaining in the crop, soil, or water; the lack of carry-over effect in the next season, the
wide spectrum of weeds controlled, no possibility of developing weed resistance to
ﬂaming, and compatibility with no-tillage production techniques (Ascard, 1995b, 1998;
Heiniger, 1999, Mojiis, 2002). The main disadvantages of ﬂame weeding are the lack of
residual effect, which requires repeated applications, the lack of selectivity for crop

safety, low speed of application, and human safety issues, (Ascard, 1995b).

100

The major factor inﬂuencing ﬂame weeding efﬁcacy is the developmental stage
of the weeds at the time of ﬂaming that determines the weed sensitivity to heat. The
stage of growth of the weeds establishes the kind and degree of protective layers, the
ligniﬁcation level, and the location of grth points. For most weed species, ﬂaming will
be most effective when weeds are in an early grth stage (Ascard, 1995a, 1998;
Campbell, 2004; Diver, 2002; Mojzis, 2002)

In addition to the growth stage of the weeds, the efficacy of the ﬂaming treatment
is determined by the combinations of two additional factors, the amount of heat
transferred ﬂom the burner and the time of exposure of the weeds to the heat (Ascard,
1998 and Heiniger, 1999). The amount of heat transferred by the ﬂamer to the weeds is
determined by the number of burners for a giving working width, the nozzle size, and the
gas pressure. The exposure time is determined by the tractor speed. Ascard (1998),
found a strong positive correlation (r2=99) between the combination of temperature-
exposure (temperature sum) and the weeds killed. These two factors combined are
commonly cited in the literature as propane consumption per hectare (Moj iiS, 2002) or
propane consumption per unit working width (Ascard, 1998).

Flame weeding is usually classiﬁed as preemergence ﬂaming or postemergence
ﬂaming. Preemergence ﬂaming is based on the presumption that the ﬁrst ﬂush of weeds
is the largest group to germinate during the season. If there is no soil disturbance after
initial tillage, new weed emergence will be reduced. If ﬂame weeding is applied after
tillage and just before crop emergence, most weeds will be killed early in the season.

For fast growing crops, preemergence ﬂame weeding would create favorable

conditions for the crop and in many cases allow the formation of full canopy which

101

impedes later weed emergence. Later ﬂushes of weeds, even though in lower quantities,
may cause serious competition for slow growing crops. In general terms, preemergence
ﬂame weeding is not sufﬁcient to avoid yield reduction due to weeds. It could work very
well for the establishment of the crop but later in the season some form of weed control is
required.

Postemergence ﬂaming consists of controlling weeds after the crop has emerged.
Timing of application is important to avoid crop damage (Campbell, 2004). For heat-
resistant crops such as cotton, corn, and sugarcane, ﬂame weeding can be applied directly
to the bottom of the plant at some grth stages. This technique, called selective
ﬂaming, controls intra-row weeds (Diver, 2002). For heat-sensitive crops,
postemergence ﬂaming can be applied using a covered ﬂamer to protect the crop ﬂom the
intense heat (Ascard, 1995b). This technique, also known as parallel ﬂaming, controls
the weeds between the rows.

The susceptibility of weeds to thermal weed control is determined by several
factors. The developmental stage of the weed is probably the most important factor;
seedlings with the shoot apex exposed are more susceptible to ﬂame weeding than older
seedlings where the shoot apex might be protected by surroundings leaves, or where
axillary buds may have developed. In addition, older seedlings have larger surface area
and larger biomass, which requires a higher ﬂaming dose to heat to a toxic temperature.
In general, broadleaves are more susceptible to heat than grasses because grasses develop
a sheath that in many cases protects the growing point. Weeds with growing points below

the soil surface might have the capacity to regrow after ﬂaming treatment, because

102

ﬂaming has a superﬁcial effect. Furthermore, annual weeds are more susceptible to ﬂame
weeding than biennials and perennials (Ascard, 1995a, 1998; Diver, 2002; MoniS, 2002).
The objective of this study was to determine the temperature and application
speed required for a covered ﬂamer to control several weed species. A second objective
was to determine the developmental stage at which several common carrot weed species

were most sensitive to ﬂaming.

Material and Methods

Experiments were conducted to determine the inﬂuence of weed developmental
stage and ﬂamer technical factors on weed control efﬁcacy. The weeds tested in this
experiment were common weeds found in Michigan carrot ﬁelds. Weeds were moved at
different speeds through a variable speed conveyer stationary ﬂamer that was built in the
Department of Agricultural Engineering at Michigan State University. The experiments
were conducted at the MSU Horticulture Teaching and Research Center.

Six weeds were chosen for this study, three grass species and three broadleaf
species (Table 48). 500 weed seeds were planted in 30 x 30 cm plastic ﬂats, spread in 4
rows. The media used was a peat-based potting mix (Baccto Professional Planting Mix,
Houston, Texas) and irrigation was applied as needed. The weeds were grown in the

greenhouse until ﬂaming experiments were initiated.

103

Table 48. Weeds species studied.

 

 

 

Monocotyledons
Common name Latin name Bayer Code
Green foxtail Setaria viridis L. SETVI
Barnyardgrass Echinochloa crus-galli L. ECHCG
Large crabgrass Digitaria sanguinalis L. DIGSA
Dicotyledons

Redroot pigweed Amaranthus retroﬂexus L. AMARE
Common ragweed Ambrosia artemisiifolia L. AMBEL
Common lambsquarters C henopodium album L. CHEAL

 

104

F lamer Design

A covered ﬂamer was designed to have better control of the ﬂame, increase heat
efﬁciency and to protect the crop ﬂom the heat (Ascard, 1995b, 1997, 1999). The ﬂamer
was designed taking into account future use on a carrot ﬁeld. The ﬂamer shield
dimensions were two meter long, 35 centimeter wide, 20 cm high in the ﬂont and 10 cm
high in the back. The shield was built ﬂom a 1.4 mm stainless steel sheet with no
insulation. Two V-shaped liquid phase burners (model LT 1‘/2 x 8 D Liquid Torch ﬂom
Flame Engineering, Inc) with a maximum capacity of 500,000 kilojoules were installed in
the ﬂont of the cover directed backwards at an angle of 67 degrees. The ﬂamer had a
medium capacity regulator (model 567 RD ﬂom Flame Engineering, Inc) and a 12 volt
D. C. Solenoid valve (model S122 ﬂom Flame Engineering, Inc) for security reasons. A
constant fuel pressure of 0.20 MPa was used and fuel consumption was estimated at 42.4
kg/h/m. Fuel consumption is deﬁned as the propane consumption, measured in kilograms

per hour, per unit working width measured in meters (Ascard, 1998).

Weed Control Experiments

Studies consisted of four treatments per weed species at two different
developmental stages plus an untreated control. The treatments were set as speed of
ﬂame application (time exposure). The four treatments or speeds were 2, 4, 6, and 8
km/h. Two different sets of weeds were established, one ﬂamed when weeds reached the
0-2 leaf stage and another when weeds reached the 2-4 leaf stage. All experiments were

repeated.

105

Temperature inside the covered ﬂamer was measured with a 4-channel type K
thermometer (Omega HH501DK, Omega Engineering, Inc., Stamford, Conneticut). The
ﬂamer generated temperatures inside the cover of 800 to 900 degrees Celsius in the ﬁrst
quarter of the cover where the burners were located, 600 to 800 degrees Celsius in the
second quarter, 500 to 700 degrees Celsius in the third quarter, and 200 to 600 degrees
Celsius in the fourth quarter. The amount of fuel consumption was kept constant,
temperature sums (treatments) were determined by the time exposure through regulating
the conveyer speed. The results Showed the combination of temperature and exposure
time required to obtain a certain level of weed control.

Stand counts and biomass measurements were collected. Two stand counts were
taken, one before the treatment application to determine the number of weeds before
ﬂaming and a second count 14 days after treatment (DAT) to determine the number of
weeds killed. Fresh weight was recorded 14 DAT in order to measure vigor of the
remaining weeds after ﬂaming. The experimental layout was arranged in a randomized
complete block design with four replications. Data ﬂom the two sets of experiments
were pooled because there was no signiﬁcant set by treatment interaction. Data ﬂom
each experiment were subjected to analysis of variance. Fisher’s Protected LSD at 01

=0.05 signiﬁcance level was used to detect differences between treatment means.

Results and Discussion
Grasses
Grass control by ﬂaming was variable depending on the species and the

developmental stage. Bamyardgrass at the 0-2 leaf stage, when ﬂamed at speed of 2, 4,

106

and 6 km/h showed no differences in stand counts 14 DAT compared to the untreated
control. However, at 8 km/h there was an increased number of live plants compared to
the untreated control (Table 49). This could be explained by an increase in germination
stimulated by heat produced during the treatment. Ascard (1995b) found in his ﬂaming
studies an increased emergence of several weed species. Ascard suggested that ﬂaming
may increase germination by breaking seed dormancy on the soil surface. Even though
the number of bamyardgrass 14 DAT was similar to the untreated plot, ﬂesh weight was
signiﬁcantly reduced for all application speeds compared to the untreated control (Table
49). Fresh weight of treated bamyardgrass at 0-2 leaf stage was reduced by 84% or more
for all speeds compared to the untreated plants. There was no signiﬁcant difference in
bamyardgrass ﬂesh weight between treatments. Although ﬂaming reduced barnyard
grass ﬂesh weight, it failed to control the number of live plants.

For bamyardgrass ﬂamed at the 2-4 leaf stage, stand counts 14 DAT were not
different ﬂom the untreated control with the exception of bamyardgrass ﬂamed at 6 km/h
where the number of plants was higher than the control. Fresh weight was signiﬁcantly
lower in the treated ﬂats than the untreated one. Fresh weight reduction in treated plots
was 80% or more compared to the control. However, there was no signiﬁcant difference
in ﬂesh weight between Speed treatments. On the other hand, there was a clear tendency
of greater ﬂesh weight reduction at slower speeds; 92% weight reduction at 2 km/h
compared to 80% at 8 km/h (Table 49). However, none of the heat treatments was

effective in killing bamyardgrass.

107

Table 49. Results ﬂom ﬂaming bamyardgrass at 0-2 and 2-4 leaves. Five hundred seeds were planted per

 

 

 

 

ﬂat
0-2 leaves 2-4 leaves
Stand Stand Fresh Stand Stand Fresh
counts counts weight counts counts weight
# plants/ﬂat # plants/ﬂat g/ﬂat # plants/ﬂat # plants/ﬂat g/ ﬂat

C‘mveyer 0 DAT 14 DAT 14 DAT 0 DAT 14 DAT 14 DAT
Speed
2 km/h 16.0 a 20.4 c 2.45 b 24.9 a 43.3 ab 6.85 b
4 km/h 17.6 a 34.1 b 4.21 b 25.6 a 49.9 ab 10.63 b
6 km/h 15.8 a 32.5 b 3.65 b 25.3 a 52.8 a 15.01 b
8 km/h 20.1 a 43.4 a 4.57 b 23.1 a 47.6 ab 16.15 b
Untreated 20.5 a 26.8 be 28.22 a 23.9 a 38.9 b 84.36 a
LSD (0.05, 7.5 8.7 11.0 8.3 11.0 11.2
CV 40.5 27.0 33.8 32.9 23.2 17.8

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

108

Green foxtail control by ﬂaming at the 0-2 leaf stage was effective (Table 50).
Stand counts 14 DAT of green foxtail ﬂamed at the 0-2 leaf stage demonstrated
signiﬁcant differences compared to the untreated control for all treatments. Although
there was no signiﬁcant difference between treatments, a clear trend was observed: the
Slower the speed of application the better the weed control. At 2 km/h weed stand counts
were reduced by almost 100%, at 4 km/h green foxtail population was reduced 96.5%; at
6 km/h weed count reduction was 94%, and weed count reduction was 78% at 8 km/h.
Green foxtail ﬂesh weight 14 DAT was signiﬁcantly lower in all treatments compared to
the untreated control. Weight reduction was greater than 96.6% for all treatments but
there was no signiﬁcant difference between treatments. Fresh weight reduction followed
the same trend as stand counts: the slower the speed the greater the weight reduction
(Table 50). Green foxtail ﬂesh weight reduction at 2 km/h and 4 km/h was almost 100%,
at 6 km/h weight reduction was 99.4%, and at 8 km/ha was 96.6%.

Different results were obtained when green foxtail was ﬂamed at the 2-4
leaf stage. Stand counts 14 DAT were signiﬁcantly lower than the untreated control,
similar to the earlier stage treatment but the reduction was not as great as in the 0-2 leaf
stage (Table 50). At 2-4 leaf stage differences between treatments were found. At 8 km,
stand counts were reduced by 33% which was signiﬁcantly less compared to 79%
reduction of the 2 km/h and 63% of the 4 km/h treatments. At 6 km/h, stand counts were
reduced by 51%, which was signiﬁcantly different compared to 79% reduction of the
treatment at 2 km/h. At 4 km/h stand counts were reduced by 62.6% and at 2 km/h stand
count reduction was 78.8% (Table 50). Only the treatment at 2 km/h had a signiﬁcant

reduction in ﬂesh weight compared to the untreated control. All other treatments were

109

Table 50. Results ﬂom ﬂaming green foxtail at 0-2 and 24 leaves. Five hundred seeds were planted per
ﬂat

 

 

 

0-2 leaves 2-4 leaves
Stand Stand Fresh Stand Stand Fresh
counts counts weight counts counts weight
# plants/ﬂat # plants/ﬂat g/ﬂat , # plants/ﬂat # plants/ﬂat g/ﬂat

SCIDZZZCYC’ 0 DAT 14 DAT 14 DAT 0 DAT 14 DAT 14 DAT
2km/h 103.03 0.2b 0.02b 61.3 a 13.8d 3.21 b
4 km/h 99.8 a 4.5 b 0.15 b 57.3 a 24.3 ed 11.03 ab
6km/h 90.5a 7.8b 0.45b 61.3a 31.8be 22.173
8 km/h 92.8 a 28.3 b 2.45 b 50.3 a 43.3 b 18.76 a
Untreated 95.8 a 129.7 a 71.04 a 55.3 a 65.0 a 24.23 a
LSD (0.05) NS a 60.8 29.8 NS 17.1 14.7
CV 26.1 32.3 30.3 15.0 14.6 60.0

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a . .
Not Slgnlﬁcant at a = 0.05

110

similar in ﬂesh weight to the control; however, it was still possible to see the inverse
trend in ﬂesh weight reduction to treatment speed with the exception of treatment 6 km/h
that ﬂesh weight reduction was lower than treatment 8 km/h. The lower ﬂesh weight
reduction at 6 km/h than at 8 km/h could be explained by a larger number of emerged
large crabgrass present at the time of ﬂaming in the 6 km/h treatment ﬂats compared to
the 8 km/h treatment ﬂats. Green foxtail (2-4 leaves) ﬂesh weight reduction at 2 km/h
was 86.8%, at 4 km/h was 54.5%, at 6 km/h weight reduction was 8.5%, and at 8 km/ha
was 22.6%. Flame weed control for green foxtail at a developmental stage of 2-4 leaves
was only acceptable when ﬂamed at 2 km/h.

Large crabgrass at the 0-2 leaf stage was more resistant to ﬂame weeding than
bamyardgrass and green foxtail (Table 51). Signiﬁcant stand count reduction was only
achieved at 2 km/h with a 51% reduction. At 4 km/h stand count reduction was 33.8%
but was not statistically different compared to untreated control. Treatments at 6 and 8
km/h demonstrated no reduction in stand counts 14 DAT. Large crabgrass ﬂesh weight
14 DAT was signiﬁcantly reduced by all treatments compared to the untreated control.
Fresh weight reduction at 2 km/h was 89%, at 4 km/h was 74%, at 6 km/h weight
reduction was 37%, and at 8 km/ha was 59.4%. The lower ﬂesh weight reduction at 6
km/h than at 8 km/h could be explained by a larger number of emerged large crabgrass
present at the time of ﬂaming in the 6 km/h treatment ﬂats compared to the 8 km/h
treatment ﬂats. Flame weed control for large crabgrass at a developmental stage of 0-2
leaves was not effective at any application speed, only obtaining marginal control when
ﬂamed at 2 km/h. Although ﬂesh weight was reduced in all speed treatments, large

crabgrass plants were still alive.

lll

Table 51. Results ﬂom ﬂaming large crabgrass at 0-2 and 2-4 leaves. Five hundred seeds were planted per

 

 

 

ﬂat
0-2 leaves 2-4 leaves
Stand Stand Fresh Stand Stand Fresh
counts counts weight counts counts weight
# plants/ ﬂat # plants/ﬂat y ﬂat . # plants/ ﬂat # plants/ﬂat g/ ﬂat

Ep::‘éeyer 0 DAT 14 DAT 14 DAT 0 DAT 14 DAT 14DAT
2 km/h 35.5 a 18.0 c 6.33 d 34.3 a 23.3 b 9.89 b
4km/h 31.8a 24.5 be 15.17 cd 39.33 41.53 16.10 ab
6 km/h 42.0 a 44.0 a 36.75 b 43.0 a 44.0 a 26.62 a
8 km/h 36.8 a 38.5 ab 23.65 be 40.5 a 34.0 ab 19.79 ab
Untreated 33.5 a 37.0 ab 58.32 a 43.5 a 41.8 a 21.01 ab
LSD (005, NS 3 18.1 16.1 NS 15.4 15.4
CV 31.6 36.2 37.3 15.4 26.4 32.4

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a . .
Not Slgnlﬁcant at a = 0.05

112

When large crabgrass was ﬂamed at the developmental stage of 2-4 leaves, only
treatment at 2 km/h had reduced stand counts 14 DAT compared to the untreated control
(Table 51). There was no signiﬁcant difference for ﬂesh weight for any of the
treatments; however, there was a decrease of ﬂesh weight of 53% for treatment at 2

km/h. Flame weed control was ineffective at any speed for large crabgrass at 2-4 leaves.

Broadleaves

As mentioned in the literature, ﬂame weed control is more effective on
broadleaves than grasses. Weed control over all broadleaf species tested was effective
for all treatment speeds and at all developmental stages.

Flame control of redroot pigweed at the 0-2 leaf stage was very effective at 2, 4,
and 6 km/h with control equal or higher than 94%. At 8 km/h redroot pigweed control
was moderately reduced to 83.8% or higher (Table 52).

Flame control of common ragweed was slightly less effective than redroot
pi gweed at the 2-4 leaf stage but still effective, controlling 88% or more of common
ragweed at 2-4 leaf stage for all treatments. Control was reduced when ﬂaming was done
at 0-2 leaves but was never less than 77.7% (Table 53). There is not a clear explanation
for this having a better control at a late developmental stage of common ragweed than an
earlier stage. Probably there was more germination after treatment in the common
ragweed 0-2 leaf stage experiment.

Common lambsquarters experiments had the same pattern as common ragweed

(Table 54). The late ﬂaming was more effective than the earlier ﬂaming. Common

113

Table 52. Results ﬂom ﬂaming redroot pigweed at 0-2 and 2-4 leaves. Five hundred seeds were planted
per ﬂat

 

 

 

 

0-2 leaves 2-4 leaves
Stand Stand Fresh Stand Stand Fresh
counts counts weight counts counts weight
# plantS/ flat # plants/ﬂat g/ ﬂat # plants/ﬂat # plants/ ﬂat g/ﬂat

;::;eye’ 0 DAT 14 DAT 14 DAT 0 DAT 14 DAT 14 DAT
2 km/h 63.3 a 2.0 b 0.17 b 74.00 a 1.63 b 0.144 b
4 km/h 63.8 a 4.0 b 0.65 b 70.00 a 2.75 b 0.345 b
6 km/h 65.8 a 2.3 b 0.21 b 70.13 a 3.75 b 0.760 b
8 km/h 55.3 a 10.8 b 2.58 b 69.38 a 6.00 b 3.056 b
Untreated 61.0 a 66.8 a 66.17 a 69.38 a 65.75 a 46.065 a
LSD (00,, NS 3 13.4 9.3 NS 8.3 7.1
CV 19.7 37.6 23.0 18.4 31.8 38.5

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a . .
Not Slgnlﬁcant at a = 0.05

114

Table 53. Results ﬂom ﬂaming common ragweed at 0-2 and 2-4 leaves. Five hundred seeds were planted
per ﬂat

 

 

 

 

0-2 leaves 2-4 leaves
Stand Stand Fresh Stand Stand Fresh
counts counts weight counts counts weight
# plants/ﬂat # plants/ﬂat g/ﬂat # plants/ﬂat # plants/ﬂat g/ﬂat

;::‘éey°’ 0 DAT 14 DAT 14 DAT 0 DAT 14 DAT 14 DAT
2 km/h 29.5 a 5.5 b 0.52 b 26.1 ab 0.9 b 0.08 b
4 km/h 30.3 a 5.1 b 0.39 b 22.0 b 0.9 b 0.05 b
6 km/h 33.0 a 5.3 b 0.46 b 29.3 a 2.8 b 0.37 b
8 km/h 33.3 a 6.5 b 0.61 b 25.5 ab 3.0 b 0.30 b
Untreated 29.8 a 29.1 a 17.27 a 25.0 ab 25.9 a 13.55 a
LSD (0.05, NS 3 3.3 4.3 4.4 6.6 1.9
CV 18.1 18.8 18.7 17.0 41.8 34.7

 

Values followed by the same letter in the same column are not statistically signiﬁcant at 0 =0.05
a . .
Not Slgnlﬁcant at a = 0.05

115

Table 54. Results ﬂom ﬂaming common lambsquarters at 0-2 and 2-4 leaves. Five hundred seeds were
planted per ﬂat

 

 

 

 

0-2 leaves 2-4 leaves
Stand Stand Fresh Stand Stand Fresh
counts counts weight counts counts weight
# plants/ﬂat # plants/ﬂat g/ﬂat . # plants/ﬂat # plants/ﬂat g/ ﬂat

:ig‘c’fye’ 0 DAT 14 DAT 14 DAT 0 DAT 14 DAT 14 DAT
2 km/h 101.4 a 1.3 b 0.024 b 76.3 ab 1.0 b 0.060 b
4km/h 103.4a 1.4b 0.101 b 72.5b 0.3 b 0.013 b
6km/h 98.1 a 3.5 b 0.116b 86.0 ab 0.4b 0.032b
8 km/h 94.8 a 4.4 b 0.127 b 107.0 a 0.3 b 0.013 b
Untreated 103.8 a 31.5 a 11.561 a 86.0 ab 80.8 a 26.183 a
LSD (00,, NS 8 3.3 1.9 32.9 6.5 1.5
CV 12.5 38.6 39.0 24.9 13.0 7.0

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a . .
Not Slgnlﬁcant at a = 0.05

116

lambsquarters control was 86% or higher for the early ﬂaming and 98.8% or higher for
the late ﬂaming, similar to results reported by Ascard (1995b). There may have been
more genuination after treatment in the 0-2 leaf stage experiment than in the 2-4 leaf
stage experiment because the weed seeds of the 2-4 leaf stage had more time to
germinate.

It seems that the heat tolerance of the broadleaf species were similarly susceptible
in both developmental stages. The difference between earlier developmental stage and the
later developmental stage could be explained not as re- growth but new germination due
to the shorter time that earlier developmental stage weed seeds were allowed to
germinate.

Ascard (1995a, 1998), Diver (2002), and MoniS (2002) reported that older
developmental stages are more heat resistant than earlier stages. This can be explained
because older stages have larger surface and larger biomass, which require a higher
ﬂaming dose to heat. Ascard (1994) found a linear relationship between weed ﬂesh
weight and the effective propane dose for 95% weed reduction. These results seem
incongruent with the ﬁndings in this study; however, the developmental stages used in
this study could be considered as an earlier developmental stage in the cited researcher’s
experiments. An additional consideration is that most of the literature cited is based on
ﬁeld experiments. These researchers also reported that grasses were more heat resistant

than broadleaves because the grass sheath protects the growing point.

117

Literature Cited

Ascard, J. 1994. Dose-response models for ﬂame weeding in relation to plant size and
density. Weed Research 34: 337-3 85

Ascard, J. 1995a. Effects of ﬂame weeding on weed species at different developmental
stages. Weed Research 35: 397-411

Ascard, J. 1995b. Thermal weed control by ﬂaming: biological and technical aspects.
Dissertation. Swedish University of Agricultural Sciences, Department of
Agricultural Engineering, Alnarp.

Ascard, J. 1997. Flame weeding: effects of fuel pressure and tandem burners. Weed
Research. 37: 77-86

Ascard, J. 1998. Comparison of ﬂaming and inﬂared radiation techniques for thermal
weed control. Weed Research. 38 (1), 69-76.

Ascard, J. 1999. Flame weeding: effects of burner angle on weed control and temperature
patterns. Acta Agriculturae Scandinavica 48: 248-254

Campbell, R. 2004. Flame weeding. Organic Agriculture Centre of Canada.
http://www.organicagcentre.ca/ResearchDatabase/ext_thermal_weed.html

Diver, S. 2002. Flame weeding for vegetable crops. ATTRA bulletin.
http://attra.ncat.org/attra-pub/PDF/ﬂameweedvegpdf

Heiniger, R. W. 1999. Controlling weeds in organic crops with ﬂame weeders. Organic
F arming Research Foundation, Information Bulletin No. 6: 17-19

Mojiis, M. 2002. Energetic requirements of ﬂame weed control. Research in Agricultural
Engineering. 48, (3): 94—97

Rahkonen, J. and H. J okela. 2003. Inﬂared radiometry for measuring plant leaf
temperature during thermal weed control treatment. Biosystems Engineering. 86
(3), 257—266

118

APPENDICES

Appendix A. List of weed species with their common name, scientiﬁc name, and Bayer code.

 

 

Common name Scientiﬁc name Bayer code

Annual bluegrass Poa annua L. POAAN
Black medic Medicago lupulina L. MEDLU
Common chickweed Ste/[aria media L. STEME
Common lam bsquarters Chenopodium album L. CHEAL
Common purslane Portulaca oleracea L. POROL
Common ragweed Ambrosia artemisiifolia L. AMBEL
Eastern black nightshade Solarium ptycanthum Dun. SOLPT
Hairy nightshade Solanum sarrachoides Sendtner SOLSA
Ladysthumb Polygonum persicaria L. POLPE
Large crabgrass Digitaria sanguinalis L. DIGSA

Mayweed chamomile Anthemis cotula L. ANTCO
Prostrate pigweed Amaranthus blitoides S. Wats. AMABL
Redroot pigweed Amaranthus retroﬂexus L. AMARE
Shepherd's-purse Capsella bursa-pastoris L. CAPBP
Yellow nutsedge Cyperus esculentus L. CYPES

 

119

Appendix 1. The effect of postemergence herbicides on carrot Stand, injury, and yield. Data ﬂom Newaygo

 

 

 

County in 2001

Stand count b Crop injury c kz/iflsdm

Rate

Treatment kg ai/ha 7 DAT 99 DAT ‘ 7 DAT 21 DAT 49 DAT 99 DAT
Linuron a 0.28 79.7 a 65.0 ab 1.0 e 1.0 d 1.0 d 11.9 a
Linuron a 0.56 75.3 ab 63.0 ab 1.7 e 1.0 d 1.0 d 10.6 ab
Flumioxazin 0.035 55.3 abc 56.3 b 7.0 b 3.0 b 1.7 bcd 8.7 bed
Flumioxazin a 0.035 48.3 be 37.7 c 9.0 a 6.0 a 3.3 a 6.7 def
Flumioxazin 0.053 56.3 abc 60.0 ab 7.7 b 2.7 b 1.7 bcd 8.9 bc
Flumioxazin a 0.053 41.0 c 34.3 e 9.0 a 6.0 a 2.7 ab 5.6 f
Oxyﬂuorfen 0.035 63.7 abc 73.7 a 5.3 c 2.0 c 1.3 cd 10.4 ab
Fluthiacet 0.0038 66.0 abc 62.7 ab 3.3 d 2.7 b 2.3 abc 6.3 ef
Flumiclorac 0.045 82.0 a 73.7 a 6.7 b 3.0 b 2.0 bed 8.2 cde
Carfcntrazone 0.01 1 57.3 abc 74.7 a 6.7 b 3.0 b 2.0 bed 7.5 c-f
Untreated 79.7 a 59.0 ab 1.0 e 2.0 c 2.7ab 6.1 ef
LSD (005, 31.0 16.05 1.2 0.43 1.09 2.18

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Treatment + sethoxydim 0.213 kg ai/ha + MS 0.25% V/v

b Number of plants per meter of row

c Visually assessed crop injury at scale of 1 to 10; 1= no injury and 10 = plant death.

120

Appendix 2. The effect of postemergence herbicides on several weeds. Data ﬂom Newaygo County 2001

 

Weed control assessment one week after treatment b

 

Rate

Treatment (kg ai/ha) DIGSA CHEAL AMARE POLPE POROL STEME
Linuron a 0.28 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Linuron “ 0.56 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Flumioxazin 0.035 6.0 be 6.3 c 10.0 a 10.0 a 10.0 a 10.0 a
Flumioxazin “ 0.035 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Flumioxazin 0.053 7.7 ab 8.0 abc 10.0 a 10.0 a 10.0 a 10.0 a
Flumioxazin a 0.053 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Oxyﬂuorfen 0.035 8.7 ab 9.0 abc 10.0 a 10.0 a 10.0 a 9.3 a
Fluthiacet 0.0038 3.3 cd 6.7 be 3.0 b 10.0 a 5.0 b 3.7 b
Flumiclorac 0.045 6.0 be 9.3 ab 10.0 a 10.0 a 9.3 a 3.7 b
Carfcntrazone 0.011 3.7 cd 7.0 be 10.0 a 9.7 b 5.0 b 1.7 bc
Untreated control 1.7 d 1.3 d 1.0 c 1.0 c 1.0 c 1.0 c
LSD (0.05) 3.2 2.748 0.889 0.296 2.427 2.618

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
’ Treatment + sethoxydim 0.213 kg ai/ha + N13 0.25% VN

b Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = plant death

121

Appendix 3. The effect of postemergence herbicides on several weeds. Data ﬂom Newaygo County 2001

 

 

Weed control assessment three weeks aﬁer treatment b
Rate

Treatment (kg ai/ha) DIGSA CHEAL AMARE POLPE POROL STEME
Linuron a 0.28 9.0 a 10.0 a 8.7 a 10.0 a 7.7 b 8.3 ab
Linuron a 0.56 8.3 a 10.0 a 10.0 a 10.0 a 8.7 ab 9.0 a
Flumioxazin 0.035 1.3 b 2.3 d 9.3 a 10.0 a 10.0 a 9.7 a
Flumioxazin a 0.035 8.7 a 9.3 ab 10.0 a 10.0 a 10.0 a 9.7 a
Flumioxazin 0.053 1.7 b 3.3 cd 10.0 a 10.0 a 10.0 a 9.7 a
Flumioxazin a 0.053 8.0 a 9.7 a 10.0 a 10.0 a 9.7 a 9.7 a
Oxyﬂuorfen 0.035 2.3 b 4.0 cd 3.3 c 7.0 ab 10.0 a 7.7 ab
Fluthiacet 0.0038 3.7 b 1.0 d 1.0 d 4.0 be 10.0 a 1.7 c
Flumiclorac 0.045 2.3 b 6.3 be 5.7 b 1.0 c 9.7 a 5.7 b
Carfcntrazone 0.011 1.3 b 3.3 cd 3.3 c 3.3 be 9.3 ab 1.0 c
Untreated control 4.0 b 2.0 d 1.0 d 7.3 ab 8.3 ab 1.0 c
LSD (005, 2.827 3.214 1.915 4.079 1.82 3.204

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Treatment + sethoxydim 0.213 kg tha + NIS 0.25% V/V

b Visually assessed weed control at scale of 1 to 10; 1: no control and 10 = plant death

122

Appendix 4. The effect of preemergence herbicides on carrot stand, injury, and biomass. Data ﬂom

 

 

Oceana County in 2001

Stand count 3 Crop injury b Yield °

Rate

Treatment (kg ai/ha) 35 DAT 35 DAT 63 DAT 125 DAT
Linuron 0.28 26.7 a 1.0 d 1.0 b 14.6 a
Linuron 0.56 22.0 b 1.0 d 1.0 b 14.2 ab
Flumioxazin 0.0011 22.7 ab 1.7 CC! 1.7 b 13.9 ab
Flumioxazin 0.0056 16.7 c 3.0 ab 2.7 a 11.8 bc
Flumioxazin 0.011 15.0 c 3.0 ab 2.7 a 10.4 c
S-Metolachlor II 0.56 24.3 ab 1.7 cd 1.0 b 11.8 be
Pendimethalin 0.84 23.7 ab 2.0 bcd 1.3 b 12.3 abc
Sulfentrazone 0.11 17.0 e 4.0 a 3.3 a 11.9 abc
Flufenacet 0.34 24.0 ab 2.3 bc 1.0 b 12.7 abc
Flufenacet + metribuzin 0.134 + 0.202 23.0 ab 1.7 cd 1.0 b 11.8 be
Untreated 24.3 ab 1.7 cd 1.3 b 10.0 c
LSD (0.051 4.085 1.152 0.904 2.732

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Number of plants per meter of row

b Visually assessed crop injury at scale of 1 to 10; 1: no injury and 10 = plant death.

c Yield in kg ﬂom 1.5 m of row.

123

Appendix 5. The effect of preemergence herbicides on several weeds. Data ﬂom Oceana County 2001

 

Weed control assessment ﬁve weeks aﬁer treatment a

 

Rate
Treatment (kg ai/ha) CHEAL AMARE CAPBP SOLPT
Linuron 0.28 7.0 ab 8.0 abc 7.7 ab 8.0 a
Linuron 0.56 9.7 ab 7.7 abc 9.7 a 9.3 a
Flumioxazin 0.0011 6.7 b 6.7 be 3.0 d 8.3 a
Flumioxazin 0.0056 9.3 ab 9.3 a 7.3 ab 10.0 a
Flumioxazin 0.01 l 9.3 ab 9.3 a 9.0 ab 10.0 a
S-Metolachlor II 0.56 8.7 ab 9.0 ab 6.3 bc 10.0 a
Pendimethalin 0.84 9.7 ab 9.7 a 4.3 cd 10.0 a
Sulfentrazone 0.11 10.0 a 9.7 a 9.3 a 10.0 a
Flufenacet 0.34 7.3 ab 9.7 a 10.0 a 9.3 a
Flufenacet + metribuzin 0.134 + 0.202 9.3 ab 9.3 a 10.0 a 8.7 a
Untreated 7.0 ab 5.7 c 3.7 cd 9.3 a
LSD (0.051 3.302 2.398 2.805 2.348

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = plant death

124

Appendix 6. The effect of postemergence herbicides on carrot stand, injury, and biomass. Data ﬂom

 

 

Oceana County in 2001

Stand count b Crop injury 0 Yield d

Rate

Treatment (kg ai/ha) 7 DAT 99 DAT _ 7 DAT 21 DAT 42 DAT 99 DAT
Linuron a 0.280 25.7 a 25.3 ab 1.3 de 1.0 d 1.3 ab 11.6 ab
Linuron a 0.561 24.3 abc 24.7 ab 1.3 de 1.3 cd 1.0 b 11.9 ab
Flumioxazin a 0.035 25.0 ab 24.3 ab 3.7 a 3.0 a 2.0 a 9.6 b
Flumioxazin a 0.053 21.3 cd 22.7 ab 3.7 a 2.7 ab 1.7 ab 10.1 ab
Flumioxazin 0.035 22.0 bed 21.3 b 2.3 be 1.7 cd 1.3 ab 11.0 ab
Flumioxazin 0.053 24.7 abc 24.0 ab 1.7 cde 1.3 cd 1.3 ab 10.9 ab
Flumioxazin 0.071 22.7 a-d 23.0 ab 3.0 ab 1.7 cd 1.3 ab 11.6 ab
Oxyﬂuorfen 0.035 23.3 a-d 24.7 ab 2.0 cd 1.0 d 1.0 b 12.0 a
22:33:: 338: + 24.3 abc 24.0 ab 1.0 e 1.0 d 1.7 ab 11.0 ab
Mesotrione 0.011 20.7 d 22.3 ab 1.7 cde 1.0 d 1.0 b 11.2 ab
Pelargonic acid 10% V/V 25.3 ab 26.3 a 3.0 ab 2.0 be 1.0 b 9.7 ab
Untreated 24.3 abc 23.0 ab 1.0 e 1.0 d 2.0 a 9.7 ab
LSD (005, 3.567 4.411 0.747 0.803 0.717 2.336

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Treatment + clethodim 0.112 kg ai/ha + NIS 0.25% VN

b Number of plants per meter of row

0 Visually assessed crop injury at scale of l to 10; 1= no injury and 10 = plant death.

d Yield in kg ﬂom 1.5 m of row.

125

Appendix 7. The effect of postemergence herbicides on Amaranthus retroﬂexus. Data ﬂom Oceana County

 

 

2001
Control of Amaranthus retroﬂexus b

Rate
Treatment (kg ai/ha) 7 DAT 21 DAT 28 DAT 42 DAT
Linuron a 0.280 7.7 c 5.7 cd 6.7 c 6.7 c
Linuron a 0.561 9.0 abc 7.3 abc 8.3 abc 9.0 ab
Flumioxazin a 0.035 9.7 ab 9.3 a 9.3 ab 9.7 a
Flumioxazin a 0.053 10.0 a 9.3 a 9.7 a 9.3 ab
Flumioxazin 0.035 10.0 a 9.3 a 9.7 a 9.7 a
Flumioxazin 0.053 9.7 ab 9.0 ab 9.7 a 9.3 ab
Flumioxazin 0.071 10.0 a 10.0 a 10.0 a 10.0 a
Oxyﬂuorfen 0.035 9.3 ab 6.3 bcd 7.7 be 8.0 be
Flufenacet + metribuzin 0.268 + 0.404 9.3 ab 7.3 abc 9.3 ab 9.3 ab
Mesotrione 0.011 8.3 be 4.0 d 6.7 e 7.0 c
Pelargonic acid 10% V/V 9.0 abc 5.0 cd 8.3 abc 7.3 c
Untreated 1.0 d 1.0 e 1.0 d 1.7 d
LSD (0.05) 1.391 2.708 1.678 1.539

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
“ Treatment + clethodim 0.112 kg ai/ha + NIS 0.25% V/V

b Visually assessed weed control at scale of 1 to 10; I: no control and 10 = plant death

126

Appendix 8. The effect of postemergence herbicides on several weeds. Data ﬂom Oceana County 2001

 

Weed control assessment 7 DAT b Weed control assessment 21 DAT

 

Rate

Treatment (kg ai/ha) CAPBP SOLPT STEME CHEAL CAPBP POLPE
Linuron a 0.280 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 9.0 a
Linuron a 0.561 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Flumioxazin a 0.035 10.0 a 10.0 a 10.0 a 9.7 a 9.7 a 10.0 a
Flumioxazin “ 0.053 10.0 a 10.0 a 10.0 a 9.7 a 9.0 ab 8.7 a
Flumioxazin 0.035 10.0 a 10.0 a 10.0 a 9.0 a 8.3 ab 8.3 a
Flumioxazin 0.053 9.7 a 10.0 a 10.0 a 9.0 a 8.3 ab 8.3 a
Flumioxazin 0.071 10.0 a 10.0 a 10.0 a 9.3 a 8.0 abc 8.3 a
Oxyﬂuorfen 0.035 10.0 a 10.0 a 10.0 a 9.0 a 6.3 be 9.3 a
22:33:)" 3:42:33 + 10.0 a 10.0 a 10.0 a 9.7 a 10.0 a 10.0 a
Mesotrione 0.011 10.0 a 10.0 a 9.7 a 8.0 a 10.0 a 8.3 a
Pelargonic acid 10% V/V 9.7 a 10.0 a 10.0 a 9.3 a 5.0 c 7.0 ab
Untreated 1.3 b 1.0 b 4.7 b 4.3 b 1.0 d 4.3 b
LSD (0.05, 0.503 0 0.408 2.264 3.157 3.579

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Treatment + clethodim 0.112 kg ai/ha + NIS 0.25% V/V
b Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

127

Appendix 9. The effect of preemergence herbicides on carrot Stand, injury, and biomass. Data ﬂom

 

 

Oceana County in 2002
C . . a Stand Y' 1d c

Rate rop mjury count b 1e
Treatment (kg ai/ha) 42 DAT 56 DAT ' 63 DAT 77 DAT 127 DAT 127 DAT
Linuron 0.561 2.3 b-e 2.0 cde 1.3 cd 1.0 c 69.5 abc 7.0 b
Oxyﬂuorfen 0.112 3.3 bcd 2.7 bed 1.3 cd 2.0 be 64.0 abc 3.3 cd
Oxyﬂuorfen 0.224 3.7 abc 3.3 abc 2.0 bcd 2.7 abc 58.0 bed 2.2 de
Flumioxazin 0.0056 4.3 ab 3.7 ab 2.3 a-d 3.7 ab 36.0 cde 1.0 de
Flumioxazin 0.011 4.3 ab 4.0 ab 3.7 a 3.7 ab 17.3 e 0.6 e
S-metolachlor 0.561 1.3 de 2.0 cde 2.7 abc 3.0 ab 43.3 b—e 2.2 de
Pendimethalin 0.841 1.3 de 2.7 bed 2.7 abc 2.7 abc 52.3 b-e 0.9 de
Sulfentrazone 0.112 5.7 a 4.7 a 3.3 ab 4.3 a 27.0 de 0.7 de
Flufenacet 0.336 1.7 cde 3.3 abc 2.0 bed 3.0 ab 51.0 b-e 1.0 de
Flufenacet + 0.134 +
metribuzin 0.202 2.7 b—e 2.0 cde 1.3 cd 2.0 be 64.7 abc 6.2 b
Clomazone 0.28 1.7 cde 1.7 de 1.0 d 2.0 be 77.0 ab 5.3 be
Untreated 1.0 e 1.0 e 1.0 d 1.0 c 97.3 a 9.9 a
LSD (005, 2.239 1.421 1.522 1.950 35.272 2.596

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed crop injury at scale of 1 to 10; 1= no injury and 10 = plant death.

b Number of plants per meter of row

c Yield in kg ﬂom 1.5 m of row.

128

Appendix 10. The effect of preemergence herbicides on several weeds. Data ﬁ'om Oceana County 2002

 

Weed control assessment 6 weeks after treatment a

 

Rate

Treatment (kg ai/ha) AMBEL POLPE MEDLU AMARE CHEAL STEME
Linuron 0.561 9.0 abc 5.3 bcd 10.0 a 10.0 a 10.0 a 10.0 a
Oxyﬂuorfen 0.112 7.7 a-e 7.7 abc 7.0 abc 9.7 a 7.7 ab 6.3 a
Oxyﬂuorfen 0.224 8.0 a-d 7.7 abc 8.3 a 9.3 a 6.3 ab 7.7 a
Flumioxazin 0.0056 3.0 fg 1.7 e 4.3 bed 5.3 b 7.0 ab 7.0 a
Flumioxazin 0.011 5.3 b-g 1.7 e 4.0 cd 9.3 a 3.7 b 7.0 a
S-metolachlor 0.561 3.3 efg 4.7 cde 3.7 cd 10.0 a 7.0 ab 7.0 a
Pendimethalin 0.841 1.0 g 2.3 de 1.3 d 4.3 b 4.7 ab 7.7 a
Sulfentrazone 0.112 4.7 c-g 9.7 a 2.0 d 10.0 a 10.0 a 10.0 a
Flufenacet 0.336 3.7 d-g 2.7 de 8.0 ab 9.3 a 7.0 ab 7.7 a
22:23:: 353: + 9.3 ab 8.3 ab 10.0 a 10.0 a 10.0 a 10.0 a
Clomazone 0.28 7.3 a-f 10.0 a 7.0 abc 10.0 a 9.7 a 10.0 a
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (005, 4.416 3.512 3.965 3.430 5.607 5.871

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = plant death

129

Appendix 11. The effect of preemergence herbicides on several weeds. Data from Oceana County 2002

 

Weed control assessment 7 weeks after treatment a

 

Rate

Treatment kg ai/ha AMARE AMBEL POLPE CHEAL MEDLU POROL STEME
Linuron 0.561 8.3 abc 9.7 ab 6.3 ab 9.7 a 10.0 a 9.0 ab 10.0 a
Oxyﬂuorfen 0.112 6.7 bed 6.3 abc 6.3 ab 7.7 ab 8.7 ab 9.0 ab 7.0 b
Oxyﬂuorfen 0.224 6.7 bed 6.0 bed 5.7 b 5.0 be 8.0 ab 10.0 a 7.3 b
Flumioxazin 0.0056 5.7 cd 2.7 cde 1.3 c 7.0 abc 6.0 be 8.3 b 10.0 a
Flumioxazin 0.011 5.0 d 3.7 cde 4.0 be 3.0 c 4.0 c 9.7 a 10.0 a
S-metolachlor 0.561 9.7 a 2.7 cde 4.3 be 4.3 be 4.0 c 10.0 a 10.0 a
Pendimethalin 0.841 7.3 a-d 2.0 e 4.0 be 5.0 be 3.0 c 10.0 a 10.0 a
Sulfentrazone 0.112 10.0 a 3.3 cde 10.0 a 10.0 a 3.7 c 10.0 a 10.0 a
Flufenacet 0.336 8.3 abc 2.3 de 4.0 be 7.0 abc 6.3 abc 10.0 a 10.0 a
22:33:?" 833: + 8.7 ab 9.0 ab 7.7 ab 10.0 a 10.0 a 8.3 b 10.0 a
Clomazone 0.28 8.3 abc 7.7 ab 10.0 a 9.3 a 6.3 abc 10.0 a 10.0 a
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (0.05) 2.748 3.734 4.204 4.061 3.778 1.100 2.030

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

130

Appendix 12. The effect of preemergence herbicides on several weeds. Data from Oceana County 2002

 

Weed control assessment 9 weeks aﬁer treatment a

 

Rate

Treatment kg ai/ha AMARE AMBEL POLPE CHEAL MEDLU POROL DIGSA
Linuron 0.561 7.3 ab 9.0 ab 4.3 bed 9.3 a 10.0 a 9.7 a 9.0 ab
Oxyﬂuorfen 0.112 4.7 be 6.0 bed 6.7 abc 8.0 ab 7.0 abc 9.3 a 9.0 ab
Oxyﬂuorfen 0.224 3.7 c 4.7 cde 4.7 bcd 5.3 be 8.0 ab 9.7 a 7.7 be
Flumioxazin 0.0056 5.0 be 4.0 de 3.7 bed 5.3 be 7.0 abc 9.0 a 5.7 e
Flumioxazin 0.011 6.7 be 3.7 de 3.3 cd 1.7 c 4.3 cd 9.7 a 8.3 ab
S-metolachlor 0.561 10.0 a 3.0 de 4.7 bed 5.0 be 5.0 bed 10.0 a 10.0 a
Pendimethalin 0.841 6.0 be 1.7 e 4.0 bed 5.3 be 3.3 d 10.0 a 9.3 ab
Sulfentrazone 0.112 10.0 a 3.3 de 9.3 a 10.0 a 4.7 cd 9.3 a 8.3 ab
Flufenacet 0.336 5.7 be 3.0 de 1.7 d 5.3 be 5.3 bed 9.0 a 10.0 a
2:33:22“ 333: + 7.7 ab 9.0 ab 7.7 ab 10.0 a 10.0 a 9.0 a 9.7 ab
Clomazone 0.28 5.7 be 8.3 abc 10.0 a 9.3 a 8.0 ab . 10.0 a 8.7 ab
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (005, 3.126 3.713 4.187 3.843 3.321 1.434 2.329

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

131

Appendix 13. The effect of preemergence herbicides on several weeds. Data from Oceana County 2002

 

Weed control assessment 11 weeks aﬁer treatment a

 

Rate

Treatment kg ai/ha AMARE AMBEL POLPE CHEAL MEDLU POROL DIGSA
Linuron 0.561 5.3 b-e 7.3 ab 3.3 b 9.0 a 10.0 a 9.3 ab 5.0 be
Oxyﬂuorfen 0.112 1.3 e 3.3 cd 1.7 b 6.0 ab 5.7 be 8.7 b 7.3 abc
Oxyﬂuorfen 0.224 1.3 e 4.3 be 1.3 b 3.0 be 8.0 abc 9.7 ab 4.0 c
Flumioxazin 0.0056 2.3 (16 3.0 cd 2.0 b 3.0 be 5.7 be 10.0 a 4.3 be
Flumioxazin 0.011 6.3 a-d 2.3 cd 2.3 b 1.0 c . 8.3 ab 9.7 ab 6.7 abc
S-metolachlor 0.561 9.3 ab 2.0 cd 7.3 a 7.3 ab 7.7 abc 10.0 a 9.7 a
Pendimethalin 0.841 7.3 abc 1.0 d 2.7 b 6.3 ab 4.3 be 10.0 a 10.0 a
Sulfentrazone 0.112 10.0 a 2.0 cd 10.0 a 10.0 a 4.0 c 9.3 ab 6.7 abc
Flufenacet 0.336 7.7 ab 2.0 cd 2.3 b 7.7 a 6.3 abc 9.3 ab 10.0 a
2:33;: 333: + 3.3 cde 8.7 a 7.3 a 9.0 a 10.0 a 8.7 b 8.3 ab
Clomazone 0.28 6.7 abc 7.3 ab 9.7 a 7.7 a 8.0 abc 10.0 a 7.0 abc
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (0.05) 4.124 3.129 3.185 4.422 4.066 1.129 4.130

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

132

Appendix 14. The effect of postemergence herbicides on carrot stand, injury, and biomass. Data from

 

 

Oceana County in 2002

C . . a Stand y. 1d c

Rate rop injury count b 1e

Treatment (kg ai/ha) 7 DAT 21 DAT 35 DAT 49 DAT 84 DAT 84 DAT
Linuron 0.561 1.3 de 1.0 a 1.3 ab 1.0 d 92.3 a 10.4 abc
Flumioxazin 0.036 2.7 abc 1.3 a 2.0 ab 2.3 ab 79.3 ab 4.9 d
Flumioxazin 0.053 3.0 abc 1.7 a 2.0 ab 2.0 be 89.7 a 5.7 cd
Flumioxazin 0.071 3.0 abc 1.0 a 2.3 a 2.7 ab 90.0 a 3.7 d
Oxyﬂuorfen 0.035 2.3 bed 1.3 a 2.3 a 3.0 a 89.7 a 3.2 d
Oxyﬂuorfen 0.071 2.0 cde 1.3 a 2.3 a 2.0 be 82.3 ab 3.3 d
Sulfentrazone 0.056 3.3 ab 1.3 a 2.0 ab 2.0 be 63.7 b 3.9 d
Flufenacet + 0.202 +
metribuzin 0.303 2.0 cde 1.0 a 1.3 ab 1.0 d 100.3 a 11.3 a
Flufenacet + 0.269 +
metribuzin 0.404 2.7 abc 1.0 a 1.7 ab 1.0 d 96.3 a 10.7 ab
Mesotrione 0.022 3.3 ab 1.0 a 1.3 ab 1.3 cd 83.7 ab 4.2 d
Mesotrione 0.045 3.7 a 1.3 a 1.7 ab 1.0 d 93.0 a 6.2 bcd
Untreated 1.0e 1.0a 1.0b 1.0d 101.03 11.9a
LSD (0.05, 1.248 0.702 1.194 0.917 22.846 4.683

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed crop injury at scale of 1 to 10; 1: no injury and 10 = plant death.

b Number of plants per meter of row

° Yield in kg from 1.5 m ofrow

133

Appendix 15. The effect of postemergence herbicides on several weeds. Data from Oceana County 2002

 

Weed control assessment one week aﬁer treatment a

 

Rate

Treatment kg ai/ha AMARE AMBEL POLPE CHEAL MEDLU
Linuron 0.561 9.7 ab 9.7 a 9.3 ab 10.0 a 10.0 a
Flumioxazin 0.036 10.0 a 8.0 a-d 7.3 abc 8.3 ab 10.0 a
Flumioxazin 0.053 10.0 a 8.7 abc 6.3 be 7.3 b 9.7 a
Flumioxazin 0.071 10.0 a 5.7 d 7.0 abc 8.0 ab 10.0 a
Oxyﬂuorfen 0.035 9.0 b 6.0 cd 6.3 be 7.7 b 9.7 a
Oxyﬂuorfen 0.071 9.0 b 6.7 bed 6.7 be 9.3 ab 10.0 a
SulfenU‘azone 0.056 10.0 a 7.7 a-d 5.0 e 9.0 ab 8.0 b
Flufenacet + metribuzin 0.202 + 0.303 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
F lufenacet + metribuzin 0.269 + 0.404 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Mesotrione 0.022 10.0 a 9.0 ab 8.0 abc 9.0 ab 9.3 a
Mesotrione 0.045 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (0.05) 0.717 2.983 3.109 2.199 0.829

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

134

Appendix 16. The effect of postemergence herbicides on several weeds. Data from Oceana County 2002

 

Weed control assessment 3 weeks aﬁer treatment 8'

 

Rate

Treatment kg ai/ha AMARE AMBEL POLPE CHEAL MEDLU POROL DIGSA
Linuron 0.561 9.3 ab 9.7 a 8.0 ab 10.0 a 10.0 a 10.0 a 10.0 a
Flumioxazin 0.036 9.0 ab 7.7 abc 6.7 abc 9.0 a 9.7 a 10.0 a 10.0 a
Flumioxazin 0.053 10.0 a 7.3 a-d 4.7 be 8.3 ab 9.7 a 10.0 a 10.0 a
Flumioxazin 0.071 9.3 ab 5.3 cd 4.0 be 5.7 b 10.0 a 10.0 a 10.0 a
Oxyﬂuorfen 0.035 7.0 b 5.3 cd 4.7 be 7.3 ab 9.7 a 9.7 a 8.3 b
Oxyﬂuorfen 0.071 9.7 a 6.3 bcd 5.0 bc 7.7 ab 10.0 a 10.0 a 9.0 ab
Sulfentrazone 0.056 9.0 ab 4.3 d 3.3 c 9.3 a 10.0 a 10.0 a 9.7 a
22:23:: gig; + 10.0 a 10.0 a 9.7 a 10.0 a 10.0 a 10.0 a 10.0 a
22:83:: 3ng + 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Mesotrione 0.022 8.3 ab 7.7 abc 3.3 c 7.7 ab 10.0 a 6.7 b 10.0 a
Mesotrione 0.045 9.3 ab 9.0 ab 7.7 ab 10.0 a 10.0 a 7.3 b 9.7 a
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (0.05, 2.344 3.073 4.053 2.690 0.442 0.702 1.007

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

135

Appendix 17. The effect of postemergence herbicides on several weeds. Data from Oceana County 2002

 

Weed control assessment 5 weeks after treatment a

 

Rate

Treatment kg ai/ha AMARE AMBEL POLPE CHEAL MEDLU POROL DIGSA
Linuron 0.561 9.3 ab 9.3 ab 8.0 abc 9.7 a 10.0 a 10.0 a 10.0 a
Flumioxazin 0.036 8.7 ab 8.0 ab 7.0 a-d 8.3 ab 9.7 a 10.0 a 10.0 a
Flumioxazin 0.053 9.7 a 8.3 ab 5.0 cd 7.0 ab 10.0 a 10.0 a 10.0 a
Flumioxazin 0.071 9.3 ab 7.0 be 5.0 cd 6.0 b 10.0 a 10.0 a 10.0 a
Oxyﬂuorfen 0.035 8.3 ab 7.0 be 7.0 a-d 7.0 ab 9.7 a 10.0 a 9.3 a
Oxyﬂuorfen 0.071 9.3 ab 7.0 be 6.0 bed 8.3 ab 10.0 a 10.0 a 9.7 a
Sulfentrazone 0.056 9.3 ab 5.3 e 4.7 cd 7.7 ab 10.0 a 10.0 a 9.7 a
22:33:“ gig + 10.0 a 10.0 a 9.7 ab 10.0 a 10.0 a 10.0 a 10.0 a
23:33:: 323: + 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
Mesotrione 0.022 8.0 b 8.3 ab 3.7 d 6.3 b 10.0 a 7.3 b 9.7 a
Mesotrione 0.045 9.0 ab 9.0 ab 7.3 a-d 9.8 a 10.0 a 7.0 b 9.3 a
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (005, 1.553 2.594 3.976 3.384 0.381 1.039 0.928

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

136

Appendix 18. The effect of postemergence herbicides on several weeds. Data from Oceana County 2002

 

Weed control assessment 7 weeks after treatment a

 

Rate

Treatment kg ai/ha AMARE AMBEL POLPE CHEAL MEDLU POROL DIGSA
Linuron 0.561 6.7 a 9.0 a 7.0 abc 9.7 a 10.0 a 9.7 ab 9.7 a
Flumioxazin 0.036 8.0 a 6.7 ab 4.7 cde 8.3 ab 10.0 a 10.0 a 9.7 a
Flumioxazin 0.053 10.0 a 6.7 ab 4.0 cde 8.7 ab 9.3 a 10.0 a 10.0 a
Flumioxazin 0.071 9.3 a 4.0 b 3.0 de 3.7 c 9.3 a 10.0 a 7.0 a
Oxyﬂuorfen 0.035 6.7 a 4.0 b 3.3 cde 4.7 c 10.0 a 10.0 a 6.3 a
Oxyfluorfen 0.071 7.7 a 4.3 b 4.0 cde 6.3 be 10.0 a 10.0 a 9.3 a
Sulfentrazone 0.056 7.7 a 3.7 b 2.3 de 10.0 a 9.7 a 10.0 a 7.0 a
22:22:: 33333 + 9.3 a 10.0 a 9.7 ab. 10.0 a 10.0 a 10.0 a 10.0 a
22:22:: 323: + 9.7 a 10.0 a 9.7 ab 10.0 a 10.0 a 10.0 a 10.0 a
Mesotrione 0.022 7.7 a 7.3 ab 2.0 e 6.0 be 10.0 a 9.3 b 9.7 a
Mesotrione 0.045 7.7 a 8.7 a 6.0 bed 10.0 a 10.0 a 5.7 c 8.0 a
Untreated 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a
LSD (0.05, 3.474 3.995 3.745 2.954 0.855 0.503 3.899

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = plant death

137

 

 

 

 

 

 

Appendix 19. The effect of preemergence herbicides on carrot stand, injury, and biomass. Data from

 

 

Newaygo County in 2003

Crop injury a Stands Yield °

Rate count

Treatment (kg ai/ha) 21 DAT 35 DAT 49 DAT 35 DAT 128 DAT
Linuron 0.28 1.3 c 1.0 e 1.3 c 257.0 a 19.1 ab
Linuron 0.561 1.3 c 1.0 e 2.0 c 258.0 a 18.5 ab
Clomazone 0.28 3.3 c 1.7 e 2.0 c 222.7 ab 18.3 ab
Clomazone 0.561 3.0 c 3.0 d 2.3 c 250.0 a 20.8 a
Mesotrione 0.112 10.0 a 10.0 a 10.0 a 0.0 d 0.0 c
Mesotrione 0.224 10.0 a 10.0 a 10.0 a 0.0 d 0.0 e
Flufenacet + metribuzin 0.179 + 0.269 6.0 b 6.3 c 5.0 b 109.0 c 14.6 b
Flufenacet + metribuzin 0.269 + 0.404 7.3 b 7.7 b 6.0 b 73.0 cd 15.1 b
Metribuzin 0.42 7.7 b 7.3 be 5.7 b 66.3 ed 15.0 b
Flufenacet 0.673 3.3 c 3.7 d 2.0 c 148.3 be 17.4 ab
Untreated 2.3 c 1.0 e 1.0 c 207.3 ab 19.1 ab
LSD (0.05, 2.246 1.289 1.799 94.291 4.762

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed crop injury at scale of l to 10; 1= no injury and 10 = plant death.
b Number of plants per meter of row
c Yield in kg from 1.5 m of row.

138

Appendix 20. The effect of preemergence herbicides on several weeds. Data from Newaygo County in

 

 

2003

Weed control assessment 5 weeks after treatment a

Rate

Treatment kg ai/ha AMARE CHEAL STEME POROL
Linuron 0.28 7.7 c 8.7 ab 8.3 b 10.0 a
Linuron 0.561 8.3 be 8.0 b 10.0 a 10.0 a
Clomazone 0.28 8.3 be 8.7 ab 10.0 a 10.0 a
Clomazone 0.561 8.7 b 9.7 a 10.0 a 10.0 a
Mesotrione 0.112 10.0 a 10.0 a 10.0 a 10.0 a
Mesotrione 0.224 10.0 a 10.0 a 10.0 a 10.0 a
Flufenacet + metribuzin 0.179 + 0.269 10.0 a 10.0 a 10.0 a 10.0 a
Flufenacet + metribuzin 0.269 + 0.404 10.0 a 10.0 a 10.0 a 10.0 a
Metribuzin 0.42 10.0 a 10.0 a 10.0 a 10.0 a
Flufenacet 0.673 8.0 be 7.3 b 7.7 b 10.0 a
Untreated 1.0 d 1.0 c 1.0 c 1.0 b
LSD (0.05, 0.928 1.456 0.864 0.000

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

139

Appendix 21. The effect of preemergence herbicides on several weeds. Data from Newaygo County in

 

 

2003
Weed control assessment 7 weeks after treatment a

Rate
Treatment kg ai/ha AMARE CHEAL SOLPT
Linuron 0.28 6.7 d 7.7 ab 8.3 b
Linuron 0.561 8.3 c 8.7 ab 9.7 ab
Clomazone 0.28 8.7 be 9.3 a 10.0 a
Clomazone 0.561 8.7 be 9.7 a 10.0 a
Mesotrione 0.1 12 10.0 a 10.0 a 10.0 a
Mesotrione 0.224 10.0 a 10.0 a 10.0 a
Flufenacet + metribuzin 0.179 + 0.269 9.7 ab 9.7 a 10.0 a
Flufenacet + metribuzin 0.269 + 0.404 9.7 ab 10.0 a 10.0 a
Metribuzin 0.42 10.0 a 10.0 a 10.0 a
Flufenacet 0.673 6.7 d 6.3 b 8.7 ab
Untreated 1.0 e 1.0 c 1.0 e
LSD (0.05, 1.197 2.363 1.365

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

140

Appendix 22. The effect of postemergence herbicides on carrot injury, yield, and weed control. Data from
Newaygo County in 2003

 

 

Carrot Weed control d
Rate

Treatment (kg ai/ha) Injuryb Yield ° AMARE CHEAL SOLSA
Linuron a 0.28 1.3 f 14.9 ab 7.3 be 8.0 ab 10.0 a
Linuron a 0.561 2.3 c 15.1 ab 10.0 a 10.0 a 10.0 a
Linuron 1.121 3.3 d 16.5 a 10.03 10.0a 10.0a
Oxyﬂuorfen 0.035 3.3 d 8.5 cd 5.3 cd 3.7 c 8.0 a
Oxyﬂuorfen 0.071 3.7 cd 7.9 d 3.7 d 3.7 c 8.3 a
Oxyﬂuorfen 0.14 4.3 be 12.0 be 6.7 be 8.0 ab 8.3 a
Flumioxazin 0.035 5.0 b 15.6 ab 6.0 bed 7.7 b 8.3 a
Flumioxazin 0.071 5.0 b 13.0 ab 7.3 be 8.3 ab 10.0 a
Mesotrione 0.05 7.3 a 5.6 d 8.3 ab 10.0 a 10.0 a
Mesotrione 0.105 7.0 a 7.2 d 10.0 a 10.0 a 10.0 a
Untreated control 1.0 f 15.5 ab 1.0 e 1.0 d 1.0 b
LSD (0.05, 0.992 3.686 2.401 2.050 3.124

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

“‘ Treatment + coc 1% WV

b Visually assessed crop injury at scale of 1 to 10; 1= no injury and 10 = plant death, 14 DAT.

° Yield in kg from 1.5 m of row, 91 DAT.

d Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = plant death, 14 DAT.

141

Appendix 23. The effect of preemergence herbicides on carrot stand, injury, and yield. Data from Oceana

 

 

County in 2003

Crop injury a Stands Yield °

Rate count

Treatment (kg ai/ha) 21 DAT ‘ 35 DAT 49 DAT 35 DAT 142 DAT
Linuron 0.561 3.3 de 1.7 ef 1.0 f 41.7 a 16.5 a
Clomazone 0.28 2.7 e 1.7 ef 1.3 f 35.3 ab 14.1 ab
Clomazone 0.561 3.0 de 2.7 de 1.3 f 36.0 ab 14.2 ab
Clomazone 1.121 4.3 bed 4.7 be 3.7 d 33.3 ab 12.4 b
Mesotrione 0.112 10.0 a 9.0 a 9.0 b 1.0 c 5.0 e
Mesotrione 0.224 10.0 a 9.0 a 9.7 ab 0.0 c 1.0 d
Mesotrione 0.448 10.0 a 10.0 a 10.0 a 0.0 c 0.0 d
Flufenacet + metribuzin 0.179 + 0.269 5.3 be 4.0 cd 3.0 de 30.3 b 14.1 ab
Flufenacet + metribuzin 0.269 + 0.404 5.7 b 6.0 b 4.7 c 30.0 b 12.8 ab
Metribuzin 0.42 4.0 cde 4.0 cd 3.0 de 38.3 ab 14.9 ab
Flufenacet 0.673 4.0 cde 3.7 cd 2.3 c 30.7 b 13.8 ab
Untreated 1.0 f 1.0 f 1.0 f 42.0 a 15.1 ab
LSD (0.05, 1.585 1.632 0.978 10.051 3.963

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed crop injury at scale of 1 to 10; 1= no injury and 10 = plant death.

Number of plants per meter of row
c Yield in kg from 1.5 m of row.

142

Appendix 24. The effect of preemergence herbicides on several weeds. Data from Oceana County in 2003

 

Weed control assessment Weed control assessment

 

Rate 35 DAT a 49 DAT

Treatment kg ai/ha AMARE ANT CO POAAN CHEAL AMARE ANT CO POAAN
Linuron 0.561 8.3 ab 10.0 a 10.0 a 10.0 a 6.7 c 10.0 a 10.0 a
Clomazone 0.28 9.0 ab 8.0 c 10.0 a 10.0 a 8.7 b 8.7 a 10.0 a
Clomazone 0.561 9.7 a 9.0 b 10.0 a 10.0 a 9.7 ab 8.7 a 10.0 a
Clomazone 1.121 10.0 a 10.0 a 10.0 a 10.0 a 9.7 ab 9.7 a 10.0 a
Mesotrione 0.112 10.0 a 10.0 a 5.3 b 10.0 a 9.3 ab 10.0 a 7.0 c
Mesotrione 0.224 10.0 a 10.0 a 7.0 b 10.0 a 10.0 a 10.0 a 7.3 be
Mesotrione 0.448 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 10.0 a 9.7 ab
:2:22::+ 3323 + 10.0 a 10.0 a 10.0 a 9.7 a 9.0 ab 10.0 a 10.0 a
22:22:: 331(6): + 10.0 a 10.0 a 10.0 a 10.0 a 9.3 ab 10.0 a 10.0 a
Metribuzin 0.42 9.3 a 10.0 a 10.0 a 10.0 a 9.0 ab 10.0 a 10.0 a
Flufenacet 0.673 7.3 b 9.7 ab 10.0 a 9.7 a 6.3 c 8.7 a 10.0 a
Untreated 1.0c 1.0d 1.0c 1.0b 1.0d 1.0b 1.0d
LSD (005, 1.678 0.761 2.842 0.408 1.060 1.457 2.574

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = plant death

143

Appendix 25. The effect of postemergence herbicides on carrot injury, yield, and weed control. Data from
Oceana County in 2003

 

 

Carrot Weed injury d

Rate
Treatment (kg ai/ha) Injuryb Yield 6 AMARE
Linuron a 0.561 1.7 gh 14.2 abc 8.3 c
Linuron 1.121 2.3 fg 14.8 ab 9.3 abc
Oxyﬂuorfen 0.035 3.0 ef 15.5 ab 9.0 abc
Oxyﬂuorfen 0.071 2.3 fg 15.7 ab 9.0 abc
Oxyﬂuorfen 0.14 3.7 de 16.8 a 9.7 ab
Flumioxazin 0.036 3.7 de 16.6 a 9.0 abc
Flumioxazin 0.071 4.0 d 17.2 a 10.0 a
Mesotrione e 0.05 5.0 c 12.1 bcd 9.3 abc
Mesotrione c 0.105 6.3 ab 10.5 ed 9.3 abc
Mesotrione 0.05 5.7 be 11.0 ed 8.7 be
Mesotrione 0.105 6.7 a 10.5 d 10.0 a
Untreated control 1.0 h 13.9 a-d 1.0 d
LSD (0.05) 0.974 3.668 1.018

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Treatment + coc 1% WV

b Visually assessed crop injury at scale of l to 10; 1= no injury and 10 = plant death, 14 DAT.

° Yield in kg from 1.5 m ofrow, 105 DAT.

d Visually assessed weed control at scale of 1 to 10; 1= no control and 10 = plant death, 14 DAT.
e Treatment + COC 1% WV + UAN 2.5% wv

144

Appendix 26. The effect of preemergence herbicides on carrot injury. Data ﬁom MSU Muck Farm in 2003

 

 

Carrot injury a
Rate

Treatment (kg ai/ha) 7 DAT 14 DAT
Linuron 1.121 2.7 cd 2.7 c
S-metolachlor 1.9 1.7 cd 2.0 c
Pendimethalin 2.24 3.0 c 2.0 c
Clomazone 0.28 1.0 d 1.7 c
Clomazone 0.561 3.0 c 1.7 c
Mesotrione 0.112 8.3 ab 9.0 a
Mesotrione 0.224 8.7 ab 9.7 a
Mesotrione 0.448 9.0 a 10.0 a
Flufenacet + metribuzin 0.269 + 0.404 7.0 b 6.7 b
Metribuzin 0.561 7.7 ab 6.0 b
Flufenacet 0.673 2.7 cd 3.3 c
Untreated control 2.0 cd 2.0 c
LSD (0.05, 1.779 1.954

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05
a Visually assessed crop injury at scale of l to 10; 1= no injury and 10 = plant death

145

Appendix 27. The effect of preemergence herbicides on several weeds. Data from MSU Muck Farm in

 

 

2003

Weed control assessment one week after treatment a

Rate

Treatment kg ai/ha CYPES POLPE AMARE POROL STEME
Linuron 1.121 7.3 abc 10.0 a 10.0 a 10.0 a 10.0 a
S-metolachlor 1.9 4.0 d 5.0 be 4.3 cd 9.3 a 3.7 b
Pendimethalin 2.24 5.7 cd 8.3 a 7.0 be 9.7 a 7.0 a
Clomazone 0.28 7.7 abc 8.0 ab 7.7 ab 9.7 a 9.7 a
Clomazone 0.561 6.7 be 8.7 a 8.3 ab 10.0 a 10.0 a
Mesotrione 0.1 12 9.0 a 9.7 a 9.3 ab 10.0 a 10.0 a
Mesotrione 0.224 8.7 ab 9.0 a 8.7 ab 10.0 a 8.7 a
Mesotrione 0.448 8.7 ab 9.7 a 10.0 a 9.7 a 9.7 a
Flufenacet + metribuzin 0.269 + 0.404 4.0 d 10.0 a 10.0 a 10.0 a 10.0 a
Metribuzin 0.561 5.7 cd 10.0 a 10.0 a 10.0 a 10.0 a
Flufenacet 0.673 4.0 d 7.7 ab 8.7 ab 10.0 a 9.0 a
Untreated 1.7 e 4.0 c 3.0 d 3.3 b 3.3 b
LSD (005) 2.250 3.144 2.734 2.165 3.283

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed weed control at scale of 1 to 10; 1: no control and 10 = plant death

146

Appendix 28. The effect of preemergence herbicides on several weeds. Data from MSU Muck Farm in

 

 

2003

Weed control assessment two weeks after treatment a

Rate

Treatment kg ai/ha CYPES: POLPE AMARE POROL AMABL
Linuron 1.121 6.0 be 9.3 a 8.3 ab 8.3 ab 10.0 a
S-metolachlor 1.9 3.0 efg 5.3 b 7.3 b 7.7 ab 9.3 a
Pendimethalin 2.24 4.0 def 8.7 a 9.3 a 10.0 a 8.7 a
Clomazone 0.28 4.7 cd 10.0 a 5.3 c 7.3 abc 6.3 b
Clomazone 0.561 4.3 de 10.0 a 5.3 c 10.0 a 6.3 b
Mesotrione 0.112 7.7 a 9.0 a 8.7 ab 4.0 d 9.3 a
Mesotrione 0.224 7.3 ab 9.0 a 9.7 a 4.7 cd 9.7 a
Mesotrione 0.448 8.0 a 10.0 a 10.0 a 6.3 bed 10.0 a
Flufenacet + metribuzin 0.269 + 0.404 2.3 gh 9.3 a 10.0 a 10.0 a 10.0 a
Metribuzin 0.561 2.7 fg 9.0 a 9.7 a 9.7 a 10.0 a
Flufenacet 0.673 3.7 d-g 8.7 a 9.3 a 9.0 ab 9.7 a
Untreated 1.0 h 3.3 b 1.0 d 1.0 e 1.0 c
LSD (005, 1.599 2.764 1.905 2.797 2.114

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

a Visually assessed weed control at scale of 1 to 10; 1: no control and 10 = plant death

147

Appendix 29. The effect of postemergence herbicides on carrot injury. Data from MSU Muck Farm in

 

 

2003
Carrot injury
Rate

Treatment (kg ai/ha) 14 DAT 42 DAT
Linurona 1.121 1.3 de 1.0c
Triﬂoxysulfuron 0.0075 7.7 b 8.3 a
Oxyﬂuorfen 0.035 1.0 e 1.0 c
Oxyﬂuorfen 0.071 1.0 e 1.3 c
Oxyﬂuorfen 0.14 2.0 cd 2.0 c
Flumioxazin 0.036 2.0 cd 1.7 c
Flumioxazin 0.071 2.7 c 1.0 c
Mesotrione 0.05 7.7 b 6.7 b
Mesotrione 0.105 9.0 a 8.3 a
Mesotrione b 0.05 9.0 a 9.3 a
Mesotrione b 0.105 9.7 a 9.3 a
Untreated control 1.0 e 1.0 c
LSD (0.05, 0.821 1.151

 

Values followed by the same letter in the same column are not statistically signiﬁcant at (1 =0.05

’Treatment + COC 1% V/V
bTreatment + coc 1% WV + UAN 2.5% WV

148

Appendix 30. The effect of postemergence herbicides on several weeds. Data from MSU Muck Farm in

 

 

2003

Weed control assessment two weeks after treatment a

Rate

Treatment kg ai/ha CYPES POLPE AMARE POROL CHEAL
Linuron b 1.121 8.0 be 10.0 a 10.0 a 10.0 a 10.0 a
Triﬂoxysulﬁuon 0.0075 7.3 c 8.7 ab 8.0 b 2.7 d 7.0 be
Oxyﬂuorfen 0.035 1.3 fg 8.7 ab 5.3 c 7.7 b 7.3 be
Oxyﬂuorfen 0.071 2.3 ef 7.3 b 8.7 ab 9.7 a 9.0 ab
Oxyﬂuorfen 0.14 3.7 d 8.3 b 9.3 ab 10.0 a 8.3 abc
Flumioxazin 0.036 2.7 de 2.3 cd 4.7 c 4.3 c 3.7 d
Flumioxazin 0.071 3.0 de 3.7 c 8.7 ab 8.0 b 6.3 c
Mesotrione 0.05 9.0 ab 10.0 a 10.0 a 1.0 e 10.0 a
Mesotrione 0.105 9.0 ab 10.0 a 10.0 a 1.3 de 10.0 a
Mesotrione ° 0.05 9.0 ab 10.0 a 10.0 a 4.7 c 10.0 a
Mesotrione ° 0.105 9.3 a 10.0 a 10.0 a 6.7 b 10.0 a
Untreated 1.0 g 1.0 d 1.0 d 1.0 e 1.0 e
LSD (005, 1.039 1.391 1.486 1.383 2.093

 

Values followed by the same letter in the same column are not statistically signiﬁcant at 0. =0.05

" Visually assessed weed control at scale of l to 10; 1= no control and 10 = plant death

b Treatment + coc 1% VN

c Treatment + COC 1% VN + UAN 2.5% V/V

149

 

 

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