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THESIS

004/

This is to certify that the

thesis entitled

Sugar Beet (Beta vulgaris) Production Following Corn
(Zea mays) and Soybeans (Glycine max) Strip-Cropping

presented by
John Patrick Burk

has been accepted towards fulfillment
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MS. Crop & Soil Sciences

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6/01 cJCIRC/DateDuepes-pJS

SUGAR BEET (Beta vulgaris) PRODUCTION FOLLOWING
CORN (Zea mays) AND SOYBEAN (Glycine max) STRIP-CROPPING

By

John P. Burk

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Crop and Soil Sciences

2002

ABSTRACT

SUGAR BEET (Beta vulgaris) PRODUCTION FOLLOWING
CORN (Zea mays) AND SOYBEANS (Glycine max) STRIP-CROPPING

by
John Patrick Burk

In the Saginaw Valley wind erosion is a serious concern due to the flat lakebed
soils. Planting corn and soybeans in strips followed by mulch tillage may reduce wind
erosion and protect sugar beet seedlings planted the following year. Field research was
conducted in 1996 and 1997 to evaluate the effectiveness of five herbicide combinations
for control of broadleaf weeds and annual grasses in corn and soybean strip-cropping.
The use of mulch tillage after the strip-cropping for protection of young sugar beet
seedlings from wind erosion and the effectiveness of three broadleaf herbicide
combinations for weed control in sugar beets was also studied. C om was planted in six
30-inch rows and cultivated once. Soybeans were drilled in twenty-six 7-inch rows and
were not cultivated. Weed density decreased in corn and soybeans when herbicides
were applied PRE followed by POST or when POST herbicides were applied twice as a
split application. Weed density in the untreated control was greater in soybean compared
with corn in both years. Residue cover after sugar beet planting was 12% and 35%
following soybean and corn, respectively before cultivation. Weed densities were greater
in sugar beets planted in soybean residue. Weed densities were reduced by at least 8 0/0 in
sugar beets by all three of the broadleaf herbicide combinations. Sugar beets following
soybean had lower plant populations, yield, sugar, and recoverable white sugar per acre

compared with sugar beets following corn.

ACKNOWLEDGMENTS

I would like to start by thanking Dr. Karen Renner, my major advisor for her insight and
support throughout my graduate career at Michigan State University. I would also like to

thank Dr. Donald R. Christenson and Dr. Timothy M. Harrigan for being members of my

graduate committee.

I would also like to thank Jerry Grigar, Chuck Lightfoote, and Mieka Emerson fiom the
NRCS office for their help in establishing the plots and collecting data. I would also like
to thank all of the people who helped me find my way through graduate school: Kelly
Nelson, Gary Powell, Andy Chomas, Brent Tharp, Jason Fausey, Matthew Rinella,
Christy Sprague, Corey Ransom, and Paul Knoerr. I have many great memories of
Michigan State University and I will always remember the people who helped make this

dream become reality.

TABLE OF CONTENTS

LIST OF TABLES .......................................................................................................... vi
LIST OF FIGURES ....................................................................................................... vii

CHAPTER 1. REVIEW OF LITERATURE

INTRODUCTION ................................................................................................. 1
HISTORY OF SUGAR BEET PRODUCTION .................................................... l
EROSION .............................................................................................................. 2
TILLAGE ............................................................................................................... 3
STRIP-CROPPING ................................................................................................ 4
CORN AND SOYBEAN HERBICIDES .............................................................. 7
SOYBEAN ROW SPACTNG ................................................................................ 8
INFLUENCE OF TILLAGE ON WEED MANAGEMENT ................................ 8
WEED COMPETITION ........................................................................................ 9
WEED CONTROL IN SUGARBEETS .............................................................. 10
SUGAR BEET HERBICIDES ............................................................................ 1 1
LITERATURE CITED ........................................................................................ 14

CHAPTER 2. SUGAR BEET (Beta vulgaris) PRODUCTION FOLLOWING
CORN (Zea mays) AND SOYBEAN (Glycine max) STRIP-CROPPING

ABSTRACT ......................................................................................................... 18
INTRODUCTION ............................................................................................... 2 1
MATERIALS AND METHODS ......................................................................... 25
RESULTS AND DISCUSSION .......................................................................... 31
SUMMARY ......................................................................................................... 37
LITERATURE CITED ........................................................................................ 38

iv

LIST OF TABLES

SUGAR BEET (Beta vulgaris) PRODUCTION FOLLOWING CORN (Zea mays)

Table 1.

Table 2.

Table 3.

Table 4.

Table 5.

Table 6.

Table 7.

Table 8.

AND SOYBEAN (Glycine max) STRIP-CROPPING

Weed densities in August of each year averaged over crop and herbicide
treatment ................................................................................................ 4O

Weed densities within each crop and herbicide treatment averaged over
years ........................................................................................................ 41

Crop yield in each herbicide treatment expressed as a percentage of the
handweeded control each year ................................................................ 42

Weed density in sugarbeet each year averaged over previous crop and
herbicide treatment .................................................................................. 43

Weed density in sugarbeet in each weed management treatment in corn
and soybean residue, averaged over years .............................................. 44

Sugarbeet stand, percent sugar, and recoverable white sugar per acre in
1996 and 1997, averaged over previous crop and herbicide treatments .45

Influence of previous crop on sugarbeet stand, root yield, and recoverable
white sugar per acre, averaged over year and herbicide treatment ......... 46

Influence of herbicide treatment each year on sugar beet stand, root yield.
percent sugar, and recoverable white sugar per acre .............................. 47

LIST OF FIGURES

SUGAR BEET (Beta vulgaris) PRODUCTION FOLLOWING CORN (Zea mays)
AND SOYBEAN (Glycine max) STRIP-CROPPING

Figure 1. Relationship of recoverable white sugar per acre to sugarbeet stand
combined over previous crop and years ........................................ 48

vi

CHAPTER 1
REVIEW OF LITERATURE
INTRODUCTION

Sugar beets (Beta vulgaris) have been grown in Michigan since 1880
(Christenson, 1998). However, due to the flat lakebed soils, vast open spaces, and fall
moldboard plowing, severe wind erosion has become a threat to the sugar beet industry.
Crops such as sugar beets are susceptible to abrasion from soil particles in the spring
(personal communication with R. Roslund, Monitor Sugar Company). The unprotected
flat lakebed soils will become compacted following a heavy rain and sugar beet seedlings
will be unable to emerge. The compacted soils also allow for the movement of soil
particles on the soil surface in high winds. These sand particles can abrade young sugar
beet seedlings.

HISTORY OF SUGAR BEET PRODUCTION

Sugar beet production began with the German chemist Andres Marggraf in 1747.
He discovered that sucrose could be extracted from the sugar beet root and converted into
a crystalline form (Fischer, 1995). Sugar beet production was introduced in the United
States in the early 1800’s. In 1830 the first sugar beet society was organized (Fischer,
1995). Sugar beets were first introduced in White Pigeon, Michigan where the first
factory was established in 1838 (Fisher, 1995). However due to a lack of technology the
factory closed its doors soon afler they opened. It was not until 1880 that a successful

factory was built.

The production of sugar beets required many laborers. The labor came
from German immigrants and laborers from Mexico. With the advances in new
technology, labor requirements are a lot less today (Fischer, 1995).

In Michigan, sugarbeets rank sixth behind corn (Zea mays L.), hay,
soybeans (Glycine max L. (Merr)), wheat (T riticum aestivum L.) and dry beans
(Plaseolus vulgaris L.) with respect to the number of acres grown (Christenson, 1998).
Sugarbeet growers in Michigan received approximately $136 million in 1990 for the
sugarbeet crop, representing 3% of the gross farm income in the state (C hristenson,
1998). Sugarbeets contribute $434 million to the Michigan economy (Christenson, 1998).
Sugarbeets are grown primarily in the Saginaw Valley and the thumb of Michigan. In
this region, sugarbeets account for 20% of the gross farm income.

The sugarbeet industry in one year will invest $95 million to produce
187,000 acres of sugarbeets. In 1998, 2,880 farmers produced 187,000 acres of
sugarbeets in Michigan. Five factories employed 2,032 workers to process the beets. In
the United States consumers pay 32% less for sugar than sugar bought in foreign
countries (Landell Mills, 1994).

EROSION
Soil erosion is the greatest threat to agriculture in the United States. Erosion rates
have surpassed the replacement costs on farm fields (Fawcett, 1995). The following is a
quote from an early Connecticut settler in 1747. The quote illustrates that soil erosion is
not something new but has influenced farming and land clearing here longer than we
know. "When our forefathers settled here, they entered a land which probably never had

been ploughed since the creation; the land being new they depended on the natural

fertility of the ground which served their purpose very well and when they had worn out
one piece of land they cleared another. Our land being thus worn out, I suppose this to be
one reason why so many are inclined to move to new places that they may raise wheat"
(Bidwell, 1925). Finding ways to reduce soil erosion and conserve moisture are
becoming more popular with conservation tillage (F awcett, 1995).

Traditional farming practices included the use of legumes in order to provide
nitrogen for the crops and limit soil erosion by providing cover during the non-croppin g
season. Using intensive tillage primarily for weed control resulted in severe erosion
when grain crops were grown (F awcett, 1995). Nearly half of the original topsoil had
eroded away following the first 100 years of farming in Iowa (Fawcett, 1995).

TILLAGE

Conservation tillage is an economical way to reduce soil erosion. The crOp
residue protects the soil surface from erosion caused by wind and rain. The amount of
protection is based on the percent cover of the soil surface. For instance, if a field has
75% cover then 75% of the soil will be protected from erosion (Fawcett, 1995).
Conservation tillage also has environmental benefits. Soil organic matter will increase
near the soil surface along with microbial populations. Phosphatase and dehydrogenase
enzyme activities, soil moisture, and organic carbon and nitrogen in the near surface of
no-till soil is also significantly higher than in conventional tillage (Doran, 1980). Such
increases in microbial activity have been associated with increased rates of pesticide

degradation with conservation tillage (Fawcett, 1995).

Moldboard plowing buries weed seeds and grains, which are an important source
of food for insects and animals. Mulch tillage leaves more seeds available for insects and
animals to eat. Conservation tillage also enhances wildlife nesting (F awcett, 1995).

Conservation tillage combined with strip-cropping in corn and soybeans can
reduce water runoff and wind erosion. Sugar beets can be protected from wind abrasion
following corn and soybean strips when combined with conservation tillage. By
controlling wheel traffic in the strips, compaction will be reduced and water runoff will
be less likely to occur (Natural Resources Conservation Service website).

Sugar beet stands were greater in reduced tillage systems than in conventional
plowed systems (Sojka et al., 1980). Root yield was not significantly lower in the
reduced tillage compared to the conventional tillage system. The ground level wind
speed was lower and soil temperatures were warmer in reduced tillage compared to
conventional tillage in the early spring in Fargo, North Dakota (Sojka et al., 1980). Sugar
beets grown in a reduced tillage study over a 3-year period in two locations were more
profitable compared to conventional tillage in Michigan (LeCureux, 1996).

STRIP-CROPPING

Strip-cropping is planting two crops of the same planter width in alternating strips
across a field. The concept of planting two crops in the same field is not new to
agriculture. However, with the use of large machinery and large farms it was impractical
for farmers to practice strip-cropping. Now with lower grain prices and rising production
costs, farmers are reevaluating strip-cropping.

Strip-cropping provides for biological diversity in a field, helps in conservation

tillage, and improves crop rotation flexibility (Fortin et al., 1987). The main benefit of

strip-cropping is to intercept sunlight more efficiently and maximize crop production
(Iragavarapu et al., 1987). Corn yields increased 20 to 40 bushels/acre in 15-foot strips
while soybeans yielded slightly less in 15-foot strips (West and Griffith, 1992). The
yield advantage in the corn is due to the outside corn rows, because these rows can
produce two to three ears of corn while within the blocks corn may only produce one ear
per plant (Mangold, 1992). Row direction is important for maximizing yield potential
(Crookston and Hill, 1979). Corn yields increased 9 to 12% in rows that were oriented
north and south, while corn yields increased 2 to 7% when the rows were planted east and
west (Iragavarapu et al., 1987).

The practical farmer's organization of Iowa reported a 20 to 30 bushels/acre
increase in corn yield in strip-cropping when compared with corn grown in blocks.
Soybean yield did not increase in the strips compared with blocks (Mangold, 1992). A
farmer in Iowa experimented with corn and soybeans in strips. Corn yield was 20 to 30
bushels greater in strips while soybeans yielded 2 bushels less in strips compared with a
block (Walter, 1993). In other research, strip-cropping at another farm resulted in a 29-
bushel/acre increase in corn and 6 bushel/acre in soybeans compared to blocks
(Reynolds, 1986). Farm profitability over a five-year period was $18 per acre greater in a
strip—cropping program (Reynolds, 1986).

Strip-cropping can improve yields and profit margins, and reduce soil erosion
(West and Griffith, 1992). A ton of soil eroding from a farm is valued at $12.50 of
nitrogen, phosphorous, and potassium. If five tons of soil are lost per acre in one year, a
farmer would lose $62.50 per acre. Strip—cropping can reduce erosion by five tons per

year (Ferguson, 1993). Corn provides greater surface residue than soybean, although

soybean residue still protects the soil from wind erosion (Seim, 1995). Strip-cropping
can also increase diversity of plant species and may lead to an increase in wildlife
populations (Mangold, 1992).

One difficulty with strip-cropping is herbicide selection (Walter, 1993). Weed
control with herbicides is difficult in strip-cropping because of sprayer boom width and a
concern for spray drift to the adjacent crop strip. Sunlight reaching the soil surface will
increase in the corn strips because there are more outside rows compared to corn grown
in blocks. With increased sunlight more weeds will germinate in the outside rows
compared to the corn grown in the in blocks. Increased light penetrating the soil surface
will cause more weeds to germinate and many postemergence herbicides such as 2,4-D
in corn cannot be applied in strip-cropping with soybeans (Klor and Klor, 1986). With
new herbicide technology strip-cropping will become easier. There are now corn and
soybeans genetically modified to be tolerant to glyphosate (N—(phosphonomethyl)
glycine) or glufosinate (butanoic acid, 2-amimo-4-(hydroxymethylphosphinyl)-
monoammonium salt) (Vroom, 1998), and these tolerant varieties could be planted in
strips and the same herbicide applied in both crops (Ferguson, 1993; Mangold, 1992).

Corn rootworms can become a problem when last years corn residue is adjacent to
this years corn crop because corn rootworms overwinter in the fields and eggs hatch from
May to June (Mangold, 1992). Root feeding by com rootwonn larvae constitutes the
greatest economic threat to profitable corn production. Severe root pruning by larvae
often results in lodging (plants no longer remain erect) of plants, and yields can be
reduced significantly if lodging is extensive. Fields with severe larval damage also can

increase harvest expenses (Gray and Steffey, 1999). Corn rootworms can become a

serious problem the following year if only four thousand corn plants per acre exist. There

are insecticides available to control corn rootworms (McGahen, 1989), however this

increases input costs to the grower and increases pesticide exposure in the environment.
CORN AND SOYBEAN HERBICIDES

On an Iowa farm practicing strip-cropping, metolachlor was applied as a
bumdown and imazethapyr was applied as a postemergence herbicide to both soybeans
and an imidazolinone tolerant corn variety (Zinkand, 1995). Imidazolinone tolerant corn
is com that was genetically modified to tolerate postemergence applications of
imazethapyr. However, there is a forty-month rotation restriction to sugar beets following
imazethapyr (Anonymous, 1998; Kells and Renner 1999). Flumetsulam/metolachlor
could be applied to both corn and soybeans but there is a 26-month rotation restriction to
sugarbeets. Herbicides that can be used in both corn and soybeans and have no
restrictions for rotation to sugar beets include metolachlor, bentazon, and flumiclorac.
Glyphosate and glufosinate could be applied with Roundup ReadyTM or Liberty Link "M
corn and soybeans (Kells and Renner, 1999). These varieties are genetically modified to
be tolerant of postemergence applications of glyphosate and glufosinate, respectively.

A study was conducted at Southern Illinois University to compare herbicide
treatments in corn. Corn treated with flumetsulam/metolachlor preplant incorporated was
not injured and the yield of 135 bushels/acre did not differ from yield of the weed free
control (Krausz and Kapusta, 1997). Corn treated with metolachlor preplant incorporated
followed by bentazon postemergence was not injured and yielded 124 bushel/acre. In
another study, corn treated with metolachlor preplant incorporated followed by bentazon

postemergence had 96 to 100% weed control and no yield loss compared with the weed

free control. Corn is usually tolerant to metolachlor except under cool and wet conditions
(Viger et al., 1991). Factors that effect metolachlor injury to corn include high
application rates, excessive moisture and sensitive varieties(Rowe et al., 1991). There
was no injury to the soybeans from a metolachlor followed by bentazon treatment (Horn g
et al., 1983). Soybean yield was similar in both reduced tillage and conventional tillage.
The preemergence and postemergence herbicide treatments had similar yields (Yenish et
aLl992)
SOYBEAN ROW SPACING

Producers are using conservation tillage in solid-seeded soybeans to increase
productivity and reduce erosion. Research at the OARDC Northwest branch has shown
yield increases in solid—seeded soybeans compared to 30-inch row soybeans (Beuerlein
and Eckert, 1987). The early canopy closure with solid seeded soybeans will help with
late season weed control. Weed control in reduced tillage is limited to postemergence
and preemergence treatments (Buhler et al., 1990).

TILLAGE INFLUENCES ON WEED MANAGEMENT

Tillage and rotation of crops will influence weed seed in the soil (Ball, 1992).
Primary tillage influences the distribution of weed seed in the soil tillage layer (Ball,
1992). There is more weed seed left near the surface in fields that were chisel plowed
rather than moldboard plowing. Reduced tillage required increased weed management to
control weeds (Ball, 1992).

Crop rotation also influences weed seed numbers in the soil. The crop rotation
dictates the time of tillage and herbicide type used (Ball, 1992). Over a several year

period, the most dominant factor influencing species composition in the seedbank and

weed flora was cropping sequence. Crop sequences dictate both time and type of tillage
operations and herbicides used (Sagar and Mortimer, 1976).

Secondary tillage such as row cultivation during the growing season also has an
influence on seedbank numbers and species composition. In a 3-yr study of irrigated row
crops, cultivation eliminated weeds between the row, which reduced seed production and
influenced seedbank number (Sagar and Mortimer, 1976). Cultivation during the
growing season reduced weed seed numbers between the rows in soybeans and in corn,
but there was no increase in weed control (Ball, 1992). No tillage or reduced tillage may
increase the potential for growth of certain weed species due to weed seed accumulation
at or near the firm soil surface and lack of control of existing weeds at planting (Buhler,
1992)

WEED COMPETITION

Common lambsquarters is very competitive in sugarbeets and less competitive in
other crops. Twenty-four common lambsquarters per 100 feet of row decreased sugar
beet root yield by 48% (Schweizer, 1983). Forty-nine common lambsquarters per 30 feet
of row decreased soybean yield by 12% in Michigan (Crook and Renner, 1990); while
nine common lambsquarters per 30 feet of row reduced soybean yield by 33% in Ohio
(Harrison, 1989). In a North Carolina study sixteen common lambsquarters per 30 feet
of row reduced soybean yield by 15% (Shurtleff, 1985). In a Canadian study corn yield
decreased when common lambsquarters density was greater than 10 plants per square
foot (Sibuga, 1985). One common lambsquarter plant will produce 72,000 seeds (Crook
and Renner, 1990). Therefore weed control in corn and soybean the year prior to

sugarbeet production is critical to reduce the potential for weeds in sugarbeets.

WEED CONTROL IN SUGAR BEETS

Weed control in previous crops is essential for sugar beet production. Sugarbeet
growers control weeds to eliminate yield loss from competition with weeds. Weeds also
reduce sugarbeet harvesting efficiency. Thirdly, weeds in storage piles at the processing
factory can spoil the sugarbeets in the pile because weeds will generate heat and mold
(Bray, 1980). Sugarbeet yield losses from weeds are dependent upon the weed species
and weed populations (Shribbs et. al., 1990). One redroot pi gweed per four sugarbeets
reduced sugarbeet yields by 24% (Wilson, 1992). Eight common lambsquarters per 30
feet of sugar beet row decreased root yield by 48% (Schweizer, 1983). A population of
170 common lambsquarters per square foot decreased sugar beet yield by 86% (Holmes
et al., 1974). Weeds that emerge soon afler sugar beet planting are more competitive
than late emerging weeds. Weeds become most competitive when they begin to shade
the crop (Wilson, 1992). Weed competition with sugar beets can be prevented if sugar
beets are kept weed free for 8 weeks afier planting (Wilson, 1992). Sugar beet yield loss
is related to total weed biomass and not to weed population (Shribbs et al., 1990).

Weed control in sugar beets depends on various fields operations because of low
crop tolerance to herbicides and a variety of weeds (Shribbs et al., 1990). Weed
management practices include pre-plant herbicides, cultivation, postemergence herbicides
and hand weeding (Wilson, 1994). With increased costs for hand labor and reduced
tillage, growers are relying more on chemical control. Even with these investments weed

interference can still reduce sugar beet root yield by 5-10% (Shribbs et al., 1990).

10

SUGAR BEET HERBICIDES

Sequential application of herbicides at planting and after sugar beet emergence
has proven effective in early season weed control (Wilson, 1994). Other popular weed
control methods have omitted the use of herbicides at planting and rely only on sequential
postemergence herbicide treatments after emergence (Wilson, 1992). There are many
advantages to postemergence herbicides. One advantage is weed problems can be
identified before the herbicide is applied. This allows for tank mixing of herbicides to
control the weeds that are present (Burtch et al., 1981). Postemergence herbicides require
less time and fuel to apply than preplant incorporated herbicides (Burtch et a1. 1981).

Chemical weed control can cost $125.00/acre in sugar beet production. The
benefit of postemergence herbicides in sugar beets compared with hand labor can range
from $77/acre to,$125.00/acre. There was a $124 to $149/acre benefit with preplant
incorporated herbicides compared with hand-weeded treatments. In addition, when
preplant incorporated and postemergence herbicides were applied the return was $1 13 to
$152/acre more than the hand-weeded control (Miller et at., 1989).

Ethofumesate and desmedipham plus phenmedipham are postemergence
herbicides used in sugar beets (Wilson, 1994). Postemergence herbicides are handed
over the row to reduce cost. The cost of postemergence herbicides can range from
$20.00 to $25.00 per acre (List, 1998). Redroot pigweed and common lambsquarters at
the cotyledon to second true leaf stage are controlled by ethofumesate (Duncan et al.,
1981). Ethofumesate alone postemergence caused less visual injury but provided less
weed control than desmedipham plus phenmedipham (Wilson, 1994). Common

lambsquarters densities were lower following phenmedipham plus desmedipham

ll

compared with ethofumesate. In other research ethofumesate plus phenmedipham
provided better initial and residual control than phenmedipham alone (Marshall et. al.,
1987). Sugar beets are not tolerant to this application if sugarbeets are smaller than 2nd
true leaf (Marshall et. al., 1987). Research conducted in 1988 and 1989 showed that
injury to sugar beets caused by phenmedipham did not cause a greater yield loss
compared with plots that had inadequate weed control (Prodoehl et al., 1992).

Broadleaf weed control can be improved by the use of split applications of low
dosages of postemergence herbicides. Broadleaf weeds in the cotyledon to two-leaf stage
can be controlled with lower rates of desmedipham with phenmedipham in split
applications (Dexter, 1994). A single application of desmedipham plus phenmedipham
applied at the 4 true leaf stage was less effective in controlling weeds than a split
application applied in the 2-4 leaf stage (Dexter, 1994). Split applications can improve
weed control. The use of low rate split applications of phenmedipham plus desmedipham
resulted in less injury to sugarbeets and increased weed control compared to single
application rates (Norris, 1991). However, split applications of sugar beet herbicides can
cause more injury than single applications to sugar beets when given the right
environmental conditions (Norris, 1991). Phytotoxicity of both phenmedipham and
desmedipham increases as light and temperature increase (Prodoehl et al., 1992). Split
applications at the reduced application rates are needed to protect sugarbeets from
herbicide injury. Damage is more severe in the two-leaf stage of sugar beet growth
(Prodoehl et al., 1992). Sugar beets at the four-leaf stage are significantly less

susceptible to injury than smaller plants.

12

Sugar beet growers need to design their weed control programs by the types of
weed problems that exist in their fields. If weed density is low, either a preplant or
postemergence applied herbicide followed by hand labor provides an economical weed
control program (Wilson, 1992). As weed density increases a preplant or preemergence
herbicide application followed by one or two postemergence herbicide applications

provides the greatest reduction in weed density (Wilson, 1992).

13

LITERATURE CITED

Anonymous. Technical Recommendations for Sugar Beet Production. 1998. Monitor
Sugar Company. p. 3.

Ball, DA. 1992. Weed seedbank response to tillage, herbicides, and crop rotation
sequence. Weed Sci. 40:654-659.

Bidwell, P.W. and J .I. Falconer. 1620-1860. History of agriculture in the northern United
States. Carnegie Institution. p.14.

Beuerlein, J. and D. Eckert. 1987. The soybean in Ohio. The Ohio State University.
pp.30-34.

Bray, W.E., 1980. The present requirements for weed control systems in sugarbeet.
ADAS quarterly review — Great Britain, Agricultural Development and Advisory Service.
36:40-46.

Buhler, DD. 1992. Population dynamics and control of annual weeds in corn (Zea mays)
as influenced by tillage systems. Weed Science. 40:241-248.

Buhler, D.D., B.D. Philbrook, and ES. Oplinger. 1990. Velvetleaf and giant foxtail
control for solid-seeded soybean production in three tillage intensities. Journal of
Production Agriculture. 3:302-308.

Burtch, L.M. and BB. Fischer. 1981. Postemergence weed control with combinations of
herbicides in different sugarbeet planting periods. Journal of the American Society of
Sugar Beet Technologists. 21 :1 12-129.

Christenson, DR. 1998. Status and potential of Michigan agriculture. Sugarbeets.
Michigan State University Extension Ag Experiment Station Special Reports. p. 1 -7.

Crook, TM. and K.A. Renner. 1990. Common lambsquarters (Chenopodium album)
competition and time of removal in soybeans (Glycine max). Weed Science. 38:358-
364.

Crookston, R.K. and DS Hill. 1979. Grain yields and land equivalent ratios from
intercropping corn and soybeans in Minnesota. Agron.J. 71:41-44.

Dexter, AG. 1994. History of sugarbeet (Beta vulgaris) herbicide rate reduction in North
Dakota and Minnesota. Weed Technology. 8:334-337.

Doran, G.W. 1980. Soil microbial and biochemical changes associated with reduced
tillage. Soil Sci. Soc. Am. J. 44:765-771.

14

Duncan, D.N., W.F. Meggitt, and D. Penner. 1981. Physiological basis of sugarbeet
(Beta vulgaris) tolerance to foliar application of ethofumesate. Weed Science. 29:648-
654.

Fawcett, RS. 1995. Impact of conservation tillage on the environment. Proc. North
Central Weed Science Society. 50:161-165.

Ferguson, J. 1993. Herbicide-friendly hybrids offer new approach. Ag Consultant. p. 8.

Fischer, J. H. 1995. Early Sugar Beet History. Monitor Sugar Company: Big Chief
News. 15:1-2.

Fortin, M.C., J. Culley, and M. Edwards. 1987. Soil water, plant growth, and yield of
strip-intercropped corn. Journal of Production Agriculture. 7:63-69.

Gray, ME. and KL. Steffey. 1999. Western Corn Rootwonns Adapts to Crop Rotation.
Agrichemical & Environmental News. Number 156. pl.

Harrison, SK, 1990. Interference and Seed Production by Common Lambsquarters
(Chenopodium album) in Soybeans (Glycine max). Weed Science. 38:113-118.

Holm, L.G., D.L. Plucknett, J .V. Pancho, and JP. Herberger. 1977. The World’s Worst
Weeds, Distribution and Biology. Univ. Press of Hawaii, Honolulu. pp.84-91.

Holmes, H.M., R.K. Pfeiffer, and W. Griffiths. 1974. Preemergence and postemergence
use of ethofumesate in sugarbeet. Proc. 12th Br. Weed Control Conf. 493-501.

Homg, L.C., R.D. Ilnicki, and M.W. Beale. 1983. Preemergence metolachlor followed
by postemergence acifluorfen and bentazon in soybean herbicides. Proc. Annual Meeting
of the Northeastern Weed Science Society. pp.39-43.

Iragavarapu, T.K. and G.W. Randall. 1987. Border effects on yields in a strip-
intercropped soybean, corn, and wheat production system. Journal of Production
Agriculture. 9:101-107.

Kells, J .J . and K.A. Renner. 1999. Weed Control Guide for Field Crops. Michigan State
Univ. Ext. Bul. E-434. pp.19-162.

Klor, D. and S. Klor. 1986. Strips Boost Yields, Profits. The New Farm. 8:15-17.

Krausz, R. F. and G. Kapusta. 1997. Weed control in field crops. Proc. North Central
Weed Science Society. 54:118-119.

Landell Mills Commodities Studies Inc. US. Sugar and Corn Sweetener Industries’
Impact on the Economy of Michigan. [Online] Available http://wwwmonitorsugar.com.
August 1994.

15

LeCureux, J. 1996. Innovative farmers’ integrated cropping systems. Michigan State
University Extension. p. 18.

List, R. 1998. Monitor Sugar herbicide prices. pp. 1-2

Mangold, G. 1992. Farmers Test Strip-crops. Soybean Digest. pp. 28-32.

Marshall, J ., R.J. Ayres, and ES. Bardsley. 1987. Phenmedipham co-forrnulations for
broad-leaved weed control in sugar beet. Proceedings of the British Crop Protection
Conference-Weeds. 12233-240.

McGahen, J.H. Corn insect control, 1989. The Agronomy Guide. pp. 45-49.

Miller, SD, and K.J. Fomstrom. 1989. Weed control and labor requirements in
sugarbeets. American Society of Sugar Beet Technologists — Journal of Sugar Beet

Research. 26: 1-9.

Narrow Strip-cropping. [Online] Available
http://www.mi.nrcs.usdsfigov/usda/gov/consheets/narrow.html, May 1997.

Norris, RF. 1991. Sugarbeet tolerance and weed control efficacy with split applications
of phenmedipham plus desmedipham. Weed Research. 31 :317-331.

Prodoehl, K.A., L.G. Campbell, and AG. Dexter. 1992. Phenmedipham + desmedipham
effects on sugarbeet. Agronomy Journal. 84:1002-1005.

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Rowe, L., J .J . Kells, and D. Penner. 1991. Efficacy and mode of action of CGA-l 541 82,
A protectant for corn (Zea mays) from metolachlor injury. Weed Science. 39:78-82.

Sagar, GR. and AM. Mortimer. 1976. An approach to the study of the population
dynamics of plants with special reference to weeds. App. Biol. 1:1-47.

Schweizer, EB. 1983. Common Lambsquarters (C henopodium album) interference in
sugarbeets (Beta vulgaris). Weed Sci. 31 :5-8.

Seim, D. 1995. Strips push corn yield. Farm Journal. p. 1.
Shribbs, J.M., D.W. Lybecker, and BE. Schweizer. 1990. Bioeconomic weed
management models for sugarbeet (Beta vulgaris) production. Weed Science. 38:436-

444.

Sibuga, K.P. and J .D. Bandeen. 1985. Effects of green foxtail and lamb's-quarters
interference in corn. Can. J. Plant Sci. 60: 1419-1425.

16

Shurtleff, J .L. and H.D. Coble. 1985. Interference of certain broadleaf weed species in
soybeans (Glycine max). Weed Science. 33:654-65 7.

Sojka, R.E., E.J. Deibert, F .B. Arnold, and J. Enz. 1980. Sugarbeet production under
reduced tillage — prospects and problems. The Station. 38:14-18.

Viger, P.R., C.V. Eberlein, and BF. Fuerst. 1991. Influence of available soil water
content, temperature and CGA-154281 on metolachlor injury to corn. Weed Science.
39:227-231.

Vroom, J. J. 1998. Crop Protection Reference. C&P Press, 888 Seventh Avenue, 28th
Floor, New York, New York 10106. 14th edition. pp 56-1381.

Walter, J. 1993. Good lookin’ strips. Corn Farmer. pp. 7-8.

West, TD. and DR. Griffith. 1992. Effect of strip-intercropping corn and soybean on
yield and profit. Agronomy Journal. 5:107-110.

Wilson, R.G. 1992. Sequential herbicide application for weed control in sugarbeets.
Journal of Sugar Beet Research. 29:1—7.

Wilson, R.G. 1994. New herbicides for postemergence application in sugarbeet (Beta
vulgaris). Weed Technology. 8:807-811.

Yenish, J.P., J .D. Doll, and DD. Buhler. 1992. Effects of tillage on vertical distribution
and viability of weed seed in soil. Weed Science. 40:429-433.

Zinkand, D. Intercropping touted as ‘extremely flexible’. [Online] Available
http://www.iowafarmercom/ggnews/fstrpcrp.htm, 1995.

17

Chapter 2

SUGAR BEET (Beta vulgaris) PRODUCTION FOLLOWING
CORN (Zea mays) AND SOYBEAN (Glycine max) STRIP-CROPPING

ABSTRACT

Planting corn and soybeans in strips followed by fall mulch tillage may reduce
wind erosion and protect sugar beet seedlings planted the following year. C om and
soybean strip-cropping trials were conducted in 1996 and 1997 on a commercial farm in
Bay County, Michigan. Corn was planted in six thirty-inch rows with alternating strips
of soybean planted in twenty-six seven-inch rows. Weed management treatments in corn
and soybeans included: flumetsulam at 0.056 lb a.i./Acre plus metolachlor at 2.1 lb
a.i./Acre PRE; metolachlor at 2.0 lb/Acre PRE followed by bentazon at 1.0 lb a.i./Acre
POST; metolachlor at 2.0 lb/Acre followed by bentazon plus flumiclorac POST; bentazon
POST; bentazon plus flumiclorac POST; bentazon E. POST and POST; bentazon E.
POST followed by bentazon plus flumiclorac POST; a hand-weeded control; and an
untreated control. Bentazon was applied at 1.0 lb a.i./Acre and flumiclorac at 0.41 lb
a.i./Acre. Corn was cultivated once and the soybeans were not cultivated. Sugar beets
were planted the year following corn and soybean strip-cropping. Crop residue was
measured in the spring before and after sugar beet planting and following first cultivation.
Pyrazon was applied pre emergence at 3 lb a.i./Acre to all treatments. Postemergence
weed management treatments in sugarbeets included a single application of desmedipham
0.037 lb a.i./acre + phenmedipham 0037 lb a.i./acre + ethofumesate 0.037 lb a.i./acre
POST; desmedipham 0.02 lb a.i./acre + phenmedipham 0.02 lb a.i./acre + ethofumesate
0.02 lb a.i./acre applied E POST and POST; desmedipham 0.085 lb a.i./aere +

phenmedipham 0.085 lb a.i./acre applied E POST and POST; hand-weeded control; and

18

an untreated control. Weed population in sugarbeets and sugar beet populations, root
yield, percent sugar and recoverable white sugar per acre were measured to determine the
influence of previous crop on sugar beet production.

Weed density in corn and soybeans was equal to that of the handweeded control
when herbicides were applied PRE followed by POST or when POST herbicides were
applied twice as a split application. Redroot pigweed densities decreased significantly
when flumiclorac was added to the tank mixture compared to the treatments that did not
contain flumiclorac. Corn and soybean yield increased when herbicides were applied
PRE followed by POST or in E-POST followed by POST treatments. Bentazon followed
by bentazon gave the highest corn yield in both 1996 and 1997. The soybean yield was
greatest in 1998 and 1997 when flumiclorac was added to the tank mixture. Weed
density in the untreated control was greater in soybean compared with corn in both years.

Residue cover in the spring afier sugar beet planting was 12 and 35% following
soybean and corn, respectively. Weed densities in sugar beets were greater in soybean
residue, reflecting the increased weed densities the previous year. Sugar beets planted in
soybean residue had lower populations, percent sugar and recoverable white sugar per
acre compared with sugar beets planted in corn residue. In 1996 and 1997 sugarbeet
populations, percent sugar and recoverable white sugar were significantly lower in the
desmedipham + phenmedipham + ethofumesate single treatment at 0.11 lb a.i./Acre
compared to the desmedipham + phenmedipham + ethofumesate split application at
reduced rate of 0.06 lb a.i./Acre. Weed densities were greater following soybean. Crop
residue was greater following corn and sugar beet population and recoverable white sugar

per acre were greater following corn. Split applications of reduced rate of herbicide did

19

not reduce sugarbeet stand and had recoverable white sugar per acre equal to the

handweeded control.

20

INTRODUCTION

Bay County, Michigan has vast open spaces and flat lakebed soils. In the spring.
wind erosion is a serious concern. The typical erosion rate on a Bay County field that is
moldboard plowed is 10 tons per acre (personal communication, Charles Li ghtfoote
Natural Resource Conservation Service). This is based on a three-year rotation of com-
soybeans-sugar beets. Erosion can be greatly reduced with the use of conservation tillage
and strip-cropping. Conservation tillage is the reduction of soil and water loss relative to
conventional tillage (Fenster, 1983). Conservation tillage in this rotation would reduce
soil loss to 6.4 tons per acre per year (Anonymous, 1980).

Strip-cropping is planting two crops of the same planter width alternating across a
field (Fortin et al., 1987). Field strip-cropping is laid out parallel to a field boundary
(Schreb et al., 1981). The benefits of field strip-cropping are greater conservation of
moisture, reduction in soil erosion, increased corn yields and earlier harvesting (Schwab
et al., 1981). Alternating strips of corn and soybeans in the same field can increase net
profit per acre (Griffith, 1992). Strip-cropping increased corn yields by 20% (Pendleton
et al., 1963). Corn yields increase 20 to 40 bushels/acre in six row strips with six rows of
soybeans alternating between (West et al., 1992). The yield increase can be attributed to
the increase in sunlight penetration on the outside corn rows (Iragavarapu, 1996).

Herbicide selection is one limiting factor that prevents farmers from strip-
cropping. Herbicide drifi to soybeans from corn or herbicide drift from soybean to corn
is a major concern. The boom width of the sprayer also presents problems when trying to

spray narrow strips separately (Walter, 1993).

21

Herbicide options that can be applied in both corn and soybeans are limited. With
the use of herbicide tolerant corn, imazethapyr can be used to both crops (Farm J oumal,
1995). On an Iowa farm practicing strip—cropping, metolachlor was applied as a
bumdown and imazethapyr was applied as a postemergence herbicide to both soybeans
and imidazolinone tolerant corn (Zinkand, 1995). Sugar beets grown in corn/soybean
rotation limit herbicide options in corn and soybeans because sugar beets are very
sensitive to herbicide residues in the soil and therefore impose many herbicide rotational
restrictions (Kells and Renner, 1999). Sugar beets cannot be planted for 26 months
following flumetsulam/metolachlor application and for 40 months following an
imazethapyr application (Kells and Renner, 1999). Herbicides that can be used in both
corn and soybeans and allow rotation to sugar beets include metolachlor, bentazon and
flumiclorac (Kells and Renner, 1999). Glyphosate and glufosinate could be applied with
Roundup ReadyTM or Liberty LinkTM corn and soybeans (Michigan State University,
1999). These varieties are genetically modified to be tolerant of postemergence
applications of glyphosate and glufosinate, respectively. Neither herbicide would restrict
rotation to sugarbeets.

Sugar beet seedlings need wind erosion protection. The wind can move soil
particles and destroy young sugar beet seedlings. In 1998 sugarbeet growers for Monitor
Sugar replanted 5,436 acres due to wind erosion and soil crusting (personal
communication with R. Roslund, Monitor Sugar Company, 1998). Sugar beets are the
most susceptible to wind erosion during establishment when the wind potential is the
highest. Tillage practices that leave residue on the soil surface have the greatest potential

for controlling wind erosion (Skidmore, 1968). Residue cover left on the soil surface will

22

protect soil from wind and water erosion. Residue cover will act like an umbrella to
intercept the raindrops and reduce the energy before it strikes the soil surface. The
residue cover will keep the soil cooler and moister (Natural Resource Conservation
Service, 1997). Strip-cropping combined with conservation tillage leaves 20 to 40%
residue on the soil surface compared to 60% crop residue afier corn and 10% residue
afier dry edible beans (personal communication with Jerry Gri gar, Natural Resource
Conservation Service, 1998). Conservation tillage will reduce both wind and water
erosion. The quantity of erosion that occurs is largely dependent on the quantity of
residue that is lefi on the soil surface. The moldboard plow will leave between 0 and 5
percent residue and the chisel plow will leave 75 percent residue on the soil surface
(Hayes and Young, 1982). In a study in the thumb of Michigan sugar beets that were
planted after the soil was chisel plowed had a population of 139 beets per 100 row foot
following the mold board plow (LeCureux, 1996). In a study conducted in Fargo, North
Dakota in 1994 and 1995 in sugar beets following corn residue, sugar beets planted into
11% com residue yielded 1 ton less than sugarbeets planted into 30% residue (Sugarbeet
Research and extension Report, 1995). However conservation tillage leaves weed seeds
near the soil surface, which can result in more weeds than conventional tillage systems
(Buhler et a1. 1990). Shallow tillage decreases seed persistence in the soil and increases
weed seedling emergence (Egley and Williams, 1990). Weed seed produced in the corn
and soybean strip crops would be near the soil surface following conservation tillage.
which could result in increased weed densities in sugarbeets the following year.

Weed control is essential in crops grown before sugar beets. There are limited

herbicide programs available to control weeds in sugar beets. Sugar beets need to be

23

weed free to prevent yield loss, improve harvesting efficiency, and improve storage when
piled. The cost of chemical weed control programs for sugar beets is between $26 and
$58/acre depending on the weed species and herbicide program. Postemergence sugar
beet herbicides must be applied before weeds exceed two inches or weed control will be
reduced (Wilson, 1992). Postemergence herbicides can be applied as a single application
or twice at reduced application rates. Two applications at reduced rates (split application)
provide better weed control than a single application (Wilson, 1992).

Strip cropping would be a desirable practice to increase corn yields and leave
more available crop residue on the soil surface prior to planting sugar beet the following
year. However, weeds must be controlled in both the corn and soybean strips to reduce
the potential for weed infestations the following year.

Studies were conducted in Michigan from 1996 to 1997 to: 1) evaluate the
effectiveness of five herbicide programs for weed control in corn and soybean strip-
cropping, 2) evaluate crop residue prior to and after sugar beet planting, and following
the first cultivation in the corn and soybean strips, 3) evaluate three weed management
programs in sugar beets following corn and soybean strip-cropping, and 4) evaluate sugar
beet populations, root yield, percent sugar, and recoverable white sugar per acre

following corn and soybean strip-cropping.

24

MATERIALS AND METHODS

Corn and soybeans

Field studies were initiated in1996 and 1997 on a Tappan loam (fine-loamy,
mixed, calcareous mesic Typic Halpaguolls) with 3% organic matter and pH of 7.8. The
study was a two-factor factorial randomized complete block with four replications. C om
and soybean strips were the main plots and herbicide treatments were the sub plots. Plots
were fifieen feet wide by seventeen feet in length, consisting of six-thirty inch rows of
corn and twenty-six seven-inch rows of soybeans. Plots were strip cropped for two years
in corn and soybean strips prior to planting sugarbeets. The corn and soybean strips were
prepared in the spring using a Sunflowerl combination tillage tool that included discs,
sweeps, harrow, and a rolling basket. The plots were established using a John Deere2
7000 twelve-thirty inch row planter. The middle six seed boxes were used and the
outside three rows were lefi off the planter. Each time the planter would turn six empty
rows remained. The empty six rows were then drilled to soybeans using a Case3 [H 5400
twenty-six by seven-inch drill. The corn variety Pioneer 3861 was planted at 30,000
seeds/acre in 1996 and 1997. Pioneer 9172 soybean was planted at 180,000 seeds/acre in
1996 and 1997. A dry fertilizer 8-10-35-2-1 (nitrogen-phosphorous-potassium-
manganese-zinc) was broadcast prior to seedbed preparation. Nitrogen in the form of
28% area ammonium nitrate was applied at the time of cultivation at 60 gal/acre (180
lbs/acre of nitrogen) with a six-row Hinicker‘1 5000 cultivator to corn at the twelve-inch

stage in both years.

 

' Sunflower, 1 Sunflower Drive, PO. Box 566, Beliot, KS 67420
2 Deere and Company, John Deere Road, Moline, IL 61265-1304
3.1.F. Case, Hamilton, Ontario L8N 4C4

4Hinicker Co., PO. Box 3407, Mankato, MN 56002-3407

25

Herbicide treatments were applied to the corn and soybean strips at the same time
with a thirty-foot pull-type sprayer with a twenty-inch nozzle spacing using flat fan
nozzles and a hydraulically driven pump. The sprayer delivered 17 gal/acre at 50 psi and
the ground speed was 6.0 mph. The weed management treatments were: flumetsulam at
0.056 lb a.i/Acre plus metolachlor at 2.1 lb a.i.lAcre PRE; metolachlor PRE at 2.0
lb/Acre plus bentazon POST at 1.0 lb a.i./Acre; metolachlor PRE at 2.0 lb/Acre plus
bentazon at 1.0 lb/Acre plus flumiclorac at 0.041 lb a.i./Acre POST; bentazon at 1.0 lb
/Acre POST; bentazon at 1.0 lb/Acre plus flumiclorac at 0.041 lb/Acre POST; bentazon
at 1.0 lb/Acre E. POST and POST; bentazon at 1.0 lb/Acre E. POST followed by
bentazon plus flumiclorac at 0.041 lb/Acre POST; a hand-weeded control; and an
untreated control. The untreated control was cultivated. Herbimax5 at 1 quart/acre was
applied in all POST herbicide treatments.

The PRE treatments were applied immediately after planting. The E. POST
herbicide treatments were applied when the corn was 4 inches tall and the soybeans were
two inches tall and at the second trifoliate growth stage. The POST application was made
when the corn was 8 inches tall and the soybeans were 4 inches tall and at the filth
trifoliate growth stage. Redroot pigweed and common lambsquarters were 1 inch in
height with 2 leaves at the time of E. POST application in both years. At the time of the
POST application these weeds were 2 inches in height with 4 leaves.

Weed densities were counted in August of both years in the corn and soybean
strip-cropping experiment. In each treatment, a 15-foot by 17.5-foot area was counted.

Weed pressure was low in both years (Tables 1 and 2).

 

26

Soybean plots were harvested using a Massey Fergusonb plot combine. The area
harvested was 15 foot wide by 17.5 feet. The corn was hand harvested from a six row by
17.5 feet area. Crop yields were converted to bushels per acre at 15.5% moisture for corn
and 13.0% moisture for soybeans. The soybean plots were harvested October 5, 1996
and October 10, 1997. The corn plots were harvested October 28, 1996 and October 30,
1997.

Sugar beet

Sugar beets were planted in 1996 and 1997 on a Tappan loam (fine-loamy, mixed,
calcareous mesic Typic Halpaquolls). In 1996 the field had 1.8% organic matter and pH
of 6.5. In 1997 a different field had a soil pH of 7.3 and 2.0% organic matter. The
previous crop in both 1996 and 1997 was strip-cropped corn and soybeans. The study
was a two factor factorial randomized complete block with four replications. The field
site was prepared by utilizing a sunflower disc chisel with three inch twisted shovels.

The site used conservation tillage. The chisel plow was pulled at 4.5 mph and was in the
soil at an 8 inch depth. The seedbed in the spring was prepared once using a sunflower
soil finisher that included discs, sweeps, harrow, and a rolling basket. The soil finisher
was pulled at 7.0 mph and at a soil depth of 3 inches. The planter was a John Deere 7000
Twelve-30 inch row planter equipped with Yetter7 row cleaners (two 13-inch steel wheels
1/4 inch thick with 16 interlocking fingers) were mounted on the seed unit to sweep

residue and soil clods off the row. In a sugar beet following corn residue study it was

 

5 Herbimax, 83% petroleum oil, 17% surfactant, Loveland Industries, Inc, PO. Box 1289, Greeley. C 0
80632
0 Massey Ferguson (AGCO), Duluth, GA 30136

7Yetter Mfg. Co. Inc., PO. Box 358. Colchester IL 62326

27

shown that row cleaners increased sugar beet population (Sugar beet Research and
Extension Report, 1995).

The planting speed was 3.5 mph and a dry fertilizer 9-21-1 1-1-1-1/4 (nitrogen-
phosphorous-potassium-zinc-manganese-boron) was applied in a band two inches to the
side and two inches below the seed at a rate of 220 lbs/acre. Pyrazon was applied at 3 lb
a.i./A in a ten-inch band over the row at planting with a hydraulically driven pump using
8003 flat fan nozzles at 35 psi.

Sugar beets were cultivated four times in 1996 and 1997. The first cultivation
was when the sugar beets were at the four true leaf stage in both years. A Buffalo8 six-
row cultivator was used with tunnel shields, cutaway discs and a single sweep to allow
the residue to flow through the cultivator. At the 8-true leaf stage in both years nitrogen
(28% urea ammonium nitrate) was applied at 75 lb N/A in 1996 and 60 1b MA in 1997
using a Hinicker 5000 cultivator with rolling shields and a single sweep. The nitrogen
rate was based on the soil nitrate test that was done two weeks prior to side-dressing both
years. The third cultivation was at the 10-true leaf stage of the sugar beet using the
Hinicker 5000 cultivator. The final cultivation was at canopy closure with the Hinicker
5000 cultivator.

The sugar beet experiment was a two-factor factorial randomized complete block
with four replications. The main plots were strips of corn or soybean residue. The
subplots were the five weed management treatments in each crop residue. Each treatment
was six rows wide, and each subplot was the length of the field (900 feet). All subplots
were treated with Pyrazon PRE at 3 lb a.i./Acre. All plots were cultivated 4 times. The

subplot treatments consisted of desmedipham at 0.0367 lb a.i./A plus phenmedipham at

28

0.0367 lb a.i./A plus ethofumesate at 0.0367 lb a.i./A POST; desmedipham at 0.085 1b/A
plus phenmedipham at 0.085 lb/A applied as a split application early POST and POST,
desmedipham at 0.02 lb/A plus phenmedipham at 0.02 lb/A plus ethofumesate at 0.02 lb
/A applied as a split application early POST and POST, a hand-weeded control, and a no
POST control only. The treatments were applied using a 12-row 30-inch band sprayer
applying herbicide in a ten-inch band at 6 mph. There were two flat fan nozzles one on
each side of each sugar beet row. A hydraulically driven pump applied 8 gal/acre at 35
p.s.i.

The sugar beet seed used in both years was MonoHybrid Company 'E- 1 7' planted
on May 4, 1996 and April 20, 1997. The soil temperature at planting in 1996 in the corn
residue was 52° F and in the soybean residue 52°F. In 1997 the soil temperature in the
corn and soybean residue was 48° F. Soil temperature was measured using five soil
thermometers randomly placed in the corn and soybean residue and then averaging the
five temperature readings for each crop residue. The rainfall for the strip—cropping and
sugar beet plot in 1996 was 28.0 inches for the growing season. In 1997, the rainfall was
16.5 inches for the growing season. Afier planting sugar beets the rainfall for 1996 in
May was 6 inches, 9 inches in June, 5.5 inches in July, .70 inches in August, and 6.8
inches in September. After planting in 1997 the rainfall for May was 2.9 inches, 4.7
inches in June, 3.6 inches in July, 3.1 inches in August and 2.2 inches in September.

Residue was measured in four areas throughout the field by counting residue
along a 100 foot tape at one-foot intervals. A line transect is a field measurement
technique that has been proven effective in estimating the percent of ground surface

covered by plant residue. It may be used to estimate crop residue, live plant cover. and

 

8 Buffalo Farm Equipment, Fleischer Mfg. Co., PO. Box 848, Columbus, NE 60602-0848

29

other ground cover at any time (Natural Resources Conservation Service, 1997). It is
most accurate when the residue is lying flat on the soil surface and is evenly distributed
across the field. The residue cover was then calculated into a percentage by the state
agronomist with the Natural Resource and Conversation service.

Sugar beet split applications were first applied when the first true leaf pairs of
sugarbeets were visible in both years. The second portion of the split application and the
single application of the full rate treatments were applied when the third true leaf pairs of
sugarbeets were visible in both years. In 1996, the temperature was 60° F and 70° F at
the time of the first and second application, respectively. In 1997, the temperature was
65° F and 75° F at the time of the first and second application, respectively.

Weed densities were counted in a 15 foot wide by 17.5 feet area in August and
converted to the number of weeds per acre (Tables 4 and 5). Sugar beets were harvested
on September 29, 1996 and October 1, 1997. Sugar beet population was counted in each
plot afier the first cultivation and at the time of harvest and was converted to number of
sugar beets per 100 feet of row. The sugar beet plots were defoliated and root yield,
percent sugar, and recoverable white sugar per acre were determined by hand digging the
center two rows of each six-row plot, 25 feet in length. The plot yield was converted to
tons/acre. Monitor Sugar Company analyzed five medium-sized sugar beets from each
plot9 for sugar beet quality. Recoverable sugar per acre was converted to pounds per
acre. % Clear Juice Purity = (Pol/((RSD%*1.14525)—1.32544))*100
RWSW=((1 8.4%Sugar)-22)*(1 -(60/(%CJ P-3.5)))/ .4 RWSA=RWST*Tons/ Acre

(Hubbell, 2001).

 

9 Monitor Sugar Company, Bay City, Michigan 48706

30

The plot design for both experiments was a split plot design with four
replications, with crop as the main plot and herbicide treatment as the subplot. Data were
subjected to analysis of variance. Significant year-by-treatment interactions occurred;
therefore the data are presented separately by year. Treatment means were separated
using Fisher's Protected LSD at the 5% level for both the strip-cropping and sugar beet
research.

RESULTS AND DISCUSSION
Corn and Soybean

Redroot pigweed and common lambsquarters densities were significantly greater
in 1997 (Table 1). Rainfall in 1997 made it difficult to apply herbicide treatments at the
correct weed height. All herbicide treatments significantly reduced redroot pi gweed and
common lambsquarters densities in corn and soybeans compared to the untreated control
(Table 2). In corn and soybeans, redroot pigweed densities in the metolachlor PRE
followed by bentazon plus flumiclorac POST, bentazon E. POST followed by bentazon
POST and bentazon E. POST followed by bentazon/flumiclorac POST treatments were
equal to the handweed control (Table 2). In com, the treatments of metolachlor PRE
followed by bentazon plus flumiclorac POST, metolachlor PRE followed by bentazon
POST, and bentazon E. POST followed by bentazon POST had common lambsquarters
densities equal to the handweed control (Table 2). In soybean, treatments of metolachlor
PRE followed by bentazon/flumiclorac POST, bentazon E. POST followed by bentazon
POST, and bentazon E. POST followed by bentazon/flumiclorac POST had common
lambsquarters densities equal to the handweed control. Total weed densities in corn were

lowest in the metolachlor PRE followed by bentazon/flumiclorac POST and the

31

bentazon/flumiclorac E. POST followed by POST treatments (Table 2). These treatments
had total weed densities similar to the handweed control. Total weed densities in
soybean in the bentazon E. POST followed by bentazon flumiclorac POST, bentazon E.
POST followed by bentazon POST, bentazon/flumiclorac POST, and metolachlor PRE
followed by bentazon/flumiclorac POST treatments were similar to the handweed
control. Herbicide treatments where flumiclorac was added significantly reduced weed
densities compared to treatments without flumiclorac. Treatments where a PRE or E.
POST was followed by a POST application had significantly lower weed densities
compared to a single PRE or POST application. By using multiple applications weeds
did not have time to exceed the optimum growth stage for herbicide application.
Furthermore, weeds that germinated following the first herbicide application were
controlled by the second herbicide application.

Weed densities influenced corn and soybean yield in 1996 and 1997 (Table 3).
Corn and soybean yields were greater in all herbicide treatments compared to the
untreated control (Table 3). The percent corn yield loss compared to the handweeded
control ranged between 2% and 14%. The percent soybean loss ranged between 3% and
20%. In 1996, corn yield in any herbicide treatment did not equal yield in the
handweeded control, while in 1997 corn yield in bentazon followed by bentazon equaled
that of the handweeded control. Soybeans in 1996 and 1997 had three treatments where
yield was equal to that of the handweeded control; however these were not necessarily
the treatments with the lowest weed density. Corn and soybean yields were not greater in
treatments with the lowest weed densities (Tables 2 and 3). Weed densities were greater

in soybean in the untreated control and yield was reduced by 20% in 1996 and 18% in

32

1997. Corn yield loss in the untreated control was 25% in 1996 and 15% in 1997.
Therefore differences in weed control in these herbicide treatments were not reflected in
yield loss due to low weed densities in both years.
Sugar Beets

The sugar beet experiment had 25% more weeds in 1996 than in 1997 (Table 4).
It was a cool wet spring with a dry summer in 1996. More weeds emerged in 1996 due to
periodic rainfall events. These rains made it difficult to spray the weeds at the proper
growth stage in sugar beets. Weed densities in sugarbeet varied by previous crop residue
and weed management treatment (Table 5). All treatments reduced weed numbers
significantly when compared to the no POST control (Table 5). One application of
desmedipham plus phenmedipham plus ethofumesate, a split application of desmedipham
plus phenmedipham plus ethofumesate, and a split application of desmedipham plus
phenmedipham reduced redroot pigweed and common lambsquarters density similarly in
corn residues (Table 5). In soybean residue, the desmedipham plus phenmedipham split
application treatment had 33% less redroot pi gweed than the desmedipham plus
phenmedipham plus ethofumesate split application treatment (Table 5). Desmedipham
plus phenmedipham has a weed control rating of “good” for redroot pi gweed compared
to ethofumesate which has only a “fair” rating for redroot pi gweed control (Kells and
Renner 1999). The desmedipham plus phenmedipham probably provided better redroot
pigweed control because it has 17% more desmedipham plus phenmedipham compared
to the desmedipham plus phenmedipham plus ethofumesate treatment at the rates applied.
In a sugar beet weed control study in 1994 it was shown that phenmedipham +

desmedipham gave 8 percent greater redroot pi gweed control compared to

33

phenmedipham + desmedipham + ethofumesate (Sugarbeet Research and Extension
Reports, 1994). The desmedipham plus phenmedipham split treatment had fewer total
weeds than the other two herbicide treatments in soybean residue, reflecting the lower
number of redroot pigweeds.
Sugar Beet Stand

The sugar beet population in 1996 following the first cultivation, combined over
the previous crop, was 116 per 100 row feet. In 1997, the population after first
cultivation was 143 per 100 row feet. Sugar beet stand was 11% lower in 1996 compared
to 1997 due to the cool, wet weather conditions that increased weed competition and
injury caused by herbicide applications in 1996 (Table 6). Reduced tillage leaves crop
residue on the soil surface, which creates cooler and wetter soils. In corn, soybeans, and
sugar beets Pythium, damping off and root rot have increased with reduced tillage
(Pedersen, 1999), and in sugar beets, root rot caused by Aphanomyces is becoming a
problem. Redroot pigweed has been found to be a host for Rhizoctonia (Potter and
Schneider, 1981), another seedling root disease. In this two-year study we planted a
sugar beet variety resistant to Rhizoctonia and we did not see any insect problems or an
increase in disease problems.

Sugar beet, root yield, percent sugar and recoverable white sugar were greater in
1997 (Table 6). In Michigan the average sugar beet yield percent sugar and recoverable
white sugar was 24% greater in 1997 versus 1996 reflecting better growing conditions
and adequate moisture in 1997 (personal communication with R. Roslund, Monitor Sugar

Company, 1998).

34

Sugar beet stand, root yield, percent sugar and RWSA were greater in sugar beets
planted into corn residue compared to soybean residue (Table 7). Sugar beet stand was
23% greater in the corn residue compared to the soybean residue. Residue remaining on
the soil surface averaged 35% following corn and 12% following soybeans. The
increased residue in corn protected the soil from surface compaction due to heavy
rainfall, and probably limited soil crusting, which can prohibit sugar beet seedling
emergence. Higher sugar beet populations produce smaller beets with a higher sugar
content (personal communication with R. Roslund, Monitor Sugar Company, 1998). In a
study conducted in 1994 and 1995 it was shown that increased sugar beet populations
increased percent sugar by 0.30 percent (Sugarbeet Research and Extension Reports,
1995). Tonnage therefore does not increase but a higher percent sugar results in a higher
RWSA (Table 7 and Figure 1).

In 1996 and 1997, the single application of desmedipham plus phenmedipham
plus ethofumesate significantly reduced sugar beet stand when compared to the hand
weeded control (Table 8). In 1996, the split application of desmedipham plus
phenmedipham also reduced sugarbeet stand compared to the handweed control. The
reason for the reduced stand with the split application of desmedipham plus
phenmedipham in 1996 was that sugar beets were sprayed the first time at the two leaf
stage resulting in herbicide related injury, but in 1997 the sugar beets were sprayed the
first time at the three leaf stage which did not result in herbicide injury. In 1994 a single
application of desmedipham + phenmedipham + ethofumesate resulted in 26% sugarbeet
injury compared to a split application of desmedipham + phenmedipham + ethofumesate

(Sugarbeet Research and Extension Reports, 1995).

35

Sugar beets treated with a split application of desmedipham plus phenmedipham
plus ethofumesate treatment had significantly higher root yields in 1996 when compared
to the other two herbicide treatments (Table 8). In 1997, yields in all herbicide
treatments were significantly greater than yield in the no POST control. The percent
sugar and RWSA were affected by herbicide treatment in both years. In 1996 the percent
sugar was lower in all herbicide treatments compared to the handweed control. However
in 1997 sugarbeets treated with the split application of desmedipham plus phenmedipham
had a higher percent sugar and sugarbeets treated with a single application of
desmedipham plus phenmedipham plus ethofumesate had a lower percent sugar than the
handweed control. RWSA was reduced in the single treatment of desmedipham plus
phenmedipham plus ethofumesate in both years compared to the handweed control. The
split application of desmedipham plus phenmedipham also reduced RWSA in 1996.

When sugarbeets or corn follow soybean strip-cropping and mulch tillage, soil
erosion is reduced by 4.1 tons per acre compared to sugarbeets following dry beans. The
erosion rate is based on the length of field which was 1000 feet, field conditions where
the slope is 0-1%, the crop residue on the surface, and the climate. The erosion index
based on the soil types was 134. Wind erosion rates were calculated from the National
Resource Conservation Technical Guide.

Implication for sugar beets

When sugar beets follow corn residue, it becomes difficult to cultivate small sugar
beets. Adjustments need to be made in order for the residue to flow through the
cultivator without plugging. If adverse weather conditions exist it becomes difficult to

dry the soil out with the residue on the soil surface.

36

SUMMARY

Weeds were controlled with seven weed management programs in corn and
soybean strip-cropping. Weed control was greater in plots where two herbicides or split-
applied herbicides were used compared to single herbicide application. Redroot pigweed
control increased with the addition of flumiclorac in corn and soybean. Corn injury
increased with metolachlor/flumetsulam and flumiclorac. Corn yield was lower in plots
treated with flumiclorac and metolachlor/flumetsulam. The herbicide programs in this
research do not restrict rotation to sugar beets. Weed management options in strip-
cropping have increased with the availability of transgenic crops such as Round up
ReadyTM and Liberty LinkTM corn and soybeans.

Sugar beet populations were greater following corn compared to soybeans in one
of two years. Corn residue improved sugar beet population in one of two years. Weeds
were controlled with all three of the POST herbicide programs following Pyrazon PRE
and including cultivation. A single application of desmedipham + phenmedipham +
ethofumesate at 0.11 lb a.i./Acre reduced sugar beet stand percent sugar, and recoverable
white sugar per acre in both years. These herbicides applied in split applications at
reduced rates of 0.06 lb a.i./Acre gave better crop tolerance and increased weed control

and root yield.

37

 

LITERATURE CITED

Anonymous. Residue Management Plan. 1997. Conservation Management Report.
Natural Resources Conservation Service. Michigan. 329B-2.

Anonymous. Sugarbeet Research and Extension Reports. 1994. 25:54—60.

Anonymous. Sugarbeet Research and Extension Reports. 1995. 26:243-
251.Anonymous. Technical Recommendations for Sugar Beet Production. 1998.
Monitor Sugar Company. p. 3.

Anonymous. United States Department of Agriculture Soil Conservation Service. 1980.
Soil Survey of Bay County, Michigan.

Bauman, T.T., M.D. White, C.E. Mowen, and S.L. Phillips. 1997. Weed control in
soybeans. North Central Weed Science Society. Research Report. 54:252.

Beuerlein, J. and D. Eckert. 1987. The soybean in Ohio. The Ohio State University.
pp.30-34.

Bredehoefi, M.W. 1994. Weed Control with Herbicides in 1994. North Dakota State
University and the University of Minnesota, Fargo.

Buhler, D.D., B.D. Philbrook, and ES. Oplinger. 1990. Velvetleaf and giant foxtail
control for solid-seeded soybean production in three tillage intensities. Journal of
Production Agriculture. 32302-308.

Egley, G.H. and RD. Williams. 1990. Decline of weed seeds and seedling emergence
over five years as affected by soil disturbance. Weed Science. 38: 504-510.

Harvey, R.G.; 1993. Broadstrike+Dual; Background and Summary of UW Research
Results. Weed Technology. 72884-889.

Hayes, WA. and HM. Young, Jr. 1982. Minimum Tillage Farming/No-Tillage Farming.
No-Till Farmer. Brookfield, WI. pp.197.

Homg, L.C., R.D. Ilnicki and M.W. Beale. 1983. Preemergence metolachlor followed by
postemergence acifluorfen and bentazon in soybeans. Proceedings Northeastern Weed
Science Society. pp. 39-43.

Kells, J.J., and K.A. Renner. 1999. Weed Control Guide for Field Crops. Michigan
State Univ. Ext. Bul. E-434. pp.19-162.

38

Norris, R. F . 1991. Sugarbeet tolerance and weed control efficacy with split applications
of phenmedipham plus desmedipham. Weed Research. 31:317-331.

Pedersen, W.L. 1999. Conservation tillage: considerations for disease control. National
Conservation Tillage Digest. 6: 14-15.

Potter, HS. and CL. Schneider. 1981. Sugarbeet diseases of the north central United
States. North Central Regional Extension Publication #140. Pp. 1-4.

Schwab, G.O., R. K. Frevert, T. W. Edminster and K. K. Barnes. Soil and Water
Conservation Engineering. Third edition. New York. John Wiley & Sons, Inc., 1981.
pp. 92-94.

 

Vroom, J. J. 1998. Crop Protection Reference. C&P Press, 888 Seventh Avenue, 28lh
Floor, New York, New York 10106. 14th edition. pp 56-1381.

West, TD. and DR. Griffith; 1992. Effect of strip-intercropping corn and soybean on
yield and profit. Journal of Production Agriculture. 52107-110.

Wilson, R.G. 1992. Sequential herbicide application for weed control in sugarbeets.
Journal of Sugar Beet Research. 29:1-7.

Zinkand, D. Intercropping touted as ‘extremely flexible’. [Online] Available
http ://www.iowafarmer.com/agnews/fstrpcrp.htm, 1995.

39

 

Table 1. Weed densities in August of each year averaged over crop
and herbicide treatment.

 

 

Redroot Pigweed Common Lambsquarter Total
Year - number/acre- - number/acre- - number/acre”
1996 393 331 724
1997 649 556 1143
Significance ** * *

 

aincluding all weed species in the plot. Minor weed species are included.
** Significance at the 0.01 probability level.
"‘ Significance at the 0.05 probability level.

40

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Table 4. Weed density in sugarbeet each year averaged over previous
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Redroot Pigweed Common Lambsquarter Total
Year - number/acre- - number/acre- - number/acre-
1996 1398 1037 2435
1997 711 1127 1837
fignificance ** ns **

 

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* Significance at the 0.05 probability level.
ns Not significant

43

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44

Table 6. Sugarbeet stand, percent sugar, and recoverable white
sugar per acre in 1996 and 1997, averaged over previous crop and
herbicide treatments.

 

 

 

 

Year Stand Root Yield % Sugar RWSA
- 100 ft of row - - T/Acre - - lb/Acre -
1996 99 14.7 14.8 3095
1997 126 27.2 16.9 6349
fignificance ** ** #18 lint

 

** Significance at the 0.01 probability level.
* Significance at the 0.05 probability level.

45

Table 7. Influence of previous crop on sugarbeet stand, root yield, and
recoverable white sugar per acre, averaged over year and herbicide treatment.

 

 

 

 

Stand Root Yield % Sugar RWSA
- 100 ft of row - - T/Acre - - lb/Acre -
Corn Residue 127 21.8 16.2 5042
Soybean Residue 98 20.1 15.4 4402

link

ggnificance

** Significance at the 0.01 probability level.

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ns Not significant

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