SOME ms OF HERBICIQAL
OILS ON BEANS

Thesis IN the Doom of Ph. D.
MICHIGAN STATE UNIVERSITY
Mark G. Wilts.
1955

{'F.

This is to certify that the
thesis entitled
Some Effects of Herbicidal 3118

on Beans

presented by

has been accepted towards fulfillment
of the requirements for

Ph, D . __ degree mm"

AH.

 

Major proiflsor (/

Date M 2 2,1/45-5-

 

 

SOME EFFEIJTS OF HERBICIDAL OILS ON BEANS

By

Mark G. Wiltse

A THESIS

Submitted to the School of Graduate Studies of Michigan
State University of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Botany and Plant Pathology
School of Science and Arts

1955

ii

ACKNOWLEDGMENTS

The author wishes to express his sincere thanks
and appreciation to Dr. B. H. Grigsby for his assistance,
advice and encouragement throughout the course of this
work.

The author also expresses his appreciation to the
Standard Oil Company of Indiana for the grant-in-aid
which made this work possible and for the herbicidal oils
which they supplied.

He particularly wishes to thank his wife, Elaine,
whose aid, patience and encouragement made this work
possible.

iii

TABLE OF CONTENTS

INTRODUCTION............ ...... .. ............. ......... . ...... .... 1
REVIEWOFLITERATUREHH................... ..... ..... 3
MATERIALSANDMETHODS................... ...... 15
EXPERIMENTAL RESULTS............ ....... .. ..... ..... 26
DI$USSION................................... ...... ...... 55
SUMMARY............................................... ..... .. ..... S9
LITERATURE CITED....... ...... ......... ........................... 62

‘APPEN’DIXOOO...OOC......OOO.O..O000......0... 00000000 .....OO....... 69

ABSTRACT

The use of oils as herbicides dates back to the early 1900's.
Research workers found that certain oil fractions could be used as
selective herbicides. Oils were later used as directed sprays on
onions, cotton and soybeans.

A study of the effects of oils upon soybeans (Glycine max, variety

 

Hawkeye), field beans (Phaseolus vulgaris, variety Michelite), lima

 

beans (Phaseolus lunatus, variety Fordhook Dwarf), wax beans (Phaseolus

 

vulgaris, variety Pencil Pod.Wax), green beans (Phaseolus vulgaris
variety Tendergreen Bush) and weeds was undertaken in the fall of 1952
and field and greenhouse tests were conducted until the spring of 1955.
Thirty-two experimental oils were tested in an effort to obtain an oil
that was non-toxic to the bean stems but would give good weed control.

A power driven Sprayer was designed and built to apply oils in
the field as a directed Spray, in a 6 inch band, at the base of the bean
stems. A small DeVilbis Sprayer unit was used for greenhouse oil
application. All oils were applied in an amount equivalent to that of
6 inch band treatments in 22 inch rows.

Yields of beans in the field, dry weight of the beans in the green-
house, observations of effects, injury ratings, micrOSCOpic examination,

and weed counts were used to evaluate the effects of oil spray appli-

cations.

SOME EFFECTS OF HERBICIDAL OILS ON BEANS

By

Mark G . Wiltse

AN ABSTRACT

Submitted to the School of Graduate Studies of Michigan
State University of.Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Botany and Plant Pathology

Year 1955

Approved (fl . N- W
/ f

iv

The following experimental oils gave good weed control with little
injury to the bean stems:

a. LS-0133 (90% mineral spirits, 10% Indocene 70)
b. 15-0150 (90% mineral spirits, 10% Indosolvent 2)
c. LS-Ol'32 (85% mineral spirits, 15% Indocene 70)
d. LS—OlSS (LO% mineral Spirits, h0% Alkylate,

20% Indosolvent 2)
e. LS-0237 (Heavy naphtha)

No significant reduction in yield occurred following oil application in
the field and about 75 per cent weed control was obtained. Grasses were

controlled better than broadleaved weeds. Ragweed (Ambrosia artemisii-

 

£2$$2.L-) appeared to be resistant to oil spray.

The typical oil injury on beans was characterized by a wilting of
the plant similar to that of a plant in drought conditions. The treated
area was water soaked in appearance and, later, turned a dark'brown.
Microscopic examinations of bean stems treated with oil revealed that
toxic oils may cause a breakdown of cells in the epidermis, cortex,
phloem and vascular cambium, and initiate, in cells adjacent to the
injured cells, a reversion to meristematic activity,

Ten gallons per acre of a herbicidal oil gave better weed control
than 5 gallons per acre and less injury to been plants than 20 gallons
per acre. .A repeat application of a herbicidal oil gave Slightly more
injury but did not decrease the yield. The resistance of been stems
to oils appeared to decrease with age. However, for ease and accuracy
of mechanical application, and for weed control, the best stage for
Spraying was the first trifoliate leaf stage. Applications of a herbi-

cidal oil in a 60° F. temperature gave less injury than applications

vii

in 70 and 80° F. temperatures. Application of a herbicidal oil to
bean stems with closed stomata gave less injury than when applied to

bean stems with cpen stomata.

The types of beans arranged in order of decreasing oil resistance

are: Field beans, soybeans, wax beans, green beans and lima beans.

INTRODUCTION

Oils have been used as herbicides for many years. The control of
all vegetation by the application of oil to roadsides, railway roadbeds,
and storage yards dates back to the early 1900's. Results obtained by
applying oils from different sections of the country indicated that
hcertain oil fractions were more phytotoxic than others. The need for a
nonpphytotoxic oil in insecticidal sprays stimulated research in oil
fraction toxicity. Certain oil fractions were found to possess low
phytotoxicity while others possessed high toxicity.

In more recent years it was found that certain plants, such as
members of the Umbelliferae family, were resistant to oils while numer—
ous broad-leaved weeds and grasses were killed by oil sprays. This led
to the use of oils as selective herbicides. Herbicidal oils also were
used as pro-emergence treatments to kill the weeds before the crop
emerged. These new uses again stimulated research into the toxicity of
various oil distillates. The knowledge obtained from this research
found immediate application in the development of oil spray methods for
weed control in several crops. Data from numerous tests indicated that
plants were more resistant to oil when it was applied at certain stages
in their growth and when the Spray was directed at the base of the
plant rather than at the terminal growing point. After Spraying equip-

ment for directed Sprays had been developed, the use of herbicidal oils

as a basal treatment was tested on several craps. The Stoddard solvent
type of oil gave little injury with excellent weed control.

Chemical weed control in beans has not been as successful as in nany
other creps. Pre-emergence treatments have proved successful with some
chemicals, but no post-emergence treatments have proven of value. Chemi-
cal treatments that are applied before the crop is up are not accepted
readily by many growers because of their reluctance to treating the soil
before the extent of the weed infestation is known. An economical method
for the chemical control of weeds in beans with post-emergence treatments
is needed. '

Bean plants have a form of growth that permits the placement of
sprays at the base of the stem during the early stage of growth, Many
annual weeds present in bean fields are susceptible to herbicidal oils
in their early stages of growth.

The studies reported here were undertaken in order to determine
the effects of different oil fractions upon bean plants and weeds and
in an attempt to devise a method for the chemical control of weeds in

beans with post-emergence Sprays,

REVIEW OF LITERATURE

The phytotoxic prOperties of crude oil or heavy oil fractions have
been known for many'years (17,20,67Yi lflany workers attempted to isolate
the toxic fractions of oil so that an oil could be obtained which was
non-phytotoxic and could.be used as a base for insecticidal sprays.

De Ong, Knight and Chamberlin (16) found a relatively high corre-
lation between aromatic content and toxicity when oil from a single
source was analyzed. Allen and Carpenter found that fractions derived
from napthenic crude oils were more toxic than fractions refined from
paraffinic crude oil (3). In 1932, Green (23) reported that aromatic
content alone was not a reliable guide to phytotoxic effects of oils.

He also found no correlation between toxicity and density, viscosity,
surface tension, and flash point.

Later workers reported that the aromatic content of oil was corre-
lated with toxicity (12,21,25,3l,h2,h9,h7). The aromatic fraction was
analyzed to determine what factor caused the increase in toxicity
(5,12,13,25,28,29,hb,80). Crafts and Reiber (12) reported that toxicity
increased with the number and size of substituted groups on the benzene
ring up to tetraisopropylbenzene. Bell and Norem (5) stated that toxicity
increased with side chains until the side chain.molecular weight equaled
the molecular weight of the benzene ring. Currier (13) working with oil

vapors reported an increase in toxicity in the order of benzene, toluene,

 

*Numbers in parenthesis refer to the literature cited on page 62.

xylene, and trimethylbenzene. Leonard and Harris (hh) also reported
this order of activity and further stated that isomers in the side
chain gave no change in toxicity. Havis (29) reported a reduction in
toxicity with an increase in side groups. Van Overbeek and Blondeau
(80) reported higher toxicity from the smaller molecules. They further
stated that the smaller molecules appear less toxic when applied in
liquid form because they evaporate faster. Griffiths (25) stated that
aromatic fractions of more than ten carbon atoms are non—selective in
toxicity. Havis (29) reported that the herbicidal properties of many
of our oils possibly come from naphthalene aromatics.

Many components other than aromatic content have been suggested
as the cause of toxicity in oils (5,12,1h,hh,h5,h9). Among these in
the order of decreasing toxicity are: aromatics, naphthenes, olefins,
and paraffins (S,28,29,35,h6,80). A double bond appears to increase A
toxicity (29,hh,h9) while molecular branching decreases toxicity (h5,80).
Leonard and Harris (ht) reported that an increase in chain length
increases toxicity up to a certain chain length. They also found that
the time required for injury to appear on plants increased with the
chain length. Several workers reported an increase in toxicity when
the oil was stored in light or was oxidized (12,29,36,80). Olefins,
under these conditions, increased in texicity more than did other frac-
tions (29). Crafts and Reiber (12) reported that the increased toxicity
was caused by peroxides which formed in the oil. Johnson and Hoskins
(36) demonstrated that acids in the oils caused an increase in toxicity.

Van Overbeek and Blondeau (80) stated that the increase in toxicity was

due to undissociated acids and that the smaller the number of carbons
in the acid molecule the greater the toxicity.

The toxicity of an oil can be predicted by determining its boiling
range (l2,h9). Crafts and Reiber (12) reported that the higher the
boiling range the larger the size of the oil molecules, and that an
oil with a low'boiling range will cause acute injury while an oil with
a high boiling range will cause chronic injury. They described acute
injury as occurring rapidly in the plant tissue and causing death of
the cells within h8 hours, while chronic injury was characterized by a
slow yellowing of the tissue with complete kill occurring several days
after treatment.

Some research has indicated that the bromine absorption number,
iodine value, aniline point and refractive index value gave an indication
of the toxicity of the oil (5,13,29). Other workers found that surface
tension and viscosity detenmine the rate of oil penetration and thus
indirectly indicate toxicity (13,50). Emulsions of certain fractions
have proved more toxic and less selective than straight oil Sprays
(12,15,29,81).

Several reports (13,22,26,39,h0,b9) stated that oil enters the
plant through the stomata and cuticle, while others indicate that the
stomata are the main points of entry (lh,78,80). Dallyn and Sweet (15)
stated that toxic oils enter the plant indiscriminately while non-toxic
oils enter only through the stomata. Greater penetration in an area
with cpen stomata than in an area with closed stomata was observed by

Dallyn (1h) and also by van Overbeek and Blondeau (80). Penetration of

tissue was not the reason for difference in susceptibility in carrots
and in beans as reported by Dallyn (1h). Plants with a waxy cuticle
resist penetration of oil other than through the stomata (80).

Host research has indicated that oil fills the intercellular spaces
after entry (13,26,h0,50,80,89,90). Two reports (31,h0) stated that
oil is then able to enter the vascular bundles; however, neither Dallyn
(1h) nor van Overbeek and Blondeau (80) were able to confirm this theory.
Some reports stated that the oil enters living cells (h0,hl,5h,89,90),
but Minshall and Helson (so) and Rohrbaugh (66) stated that there was
no penetration. Havis (29), and van Overbeek and.Blondeau (80) found
no penetration of living cells by non-toxic oils but Observed pene-
tration by toxic oils. Crafts and Reiber (12) found that oil would
creep on the leaves of grass as much as six.inches from the point of
application.

Several studies have been made on the effect of oils upon tran-
spiration, reapiration, and photosythesis (2h,3l,37,38,h0,50).
Transpiration was sharply reduced in all treated plants but returned to
a normal rate in the resistant plants (38,hO,SO). Helson and Minshall
(31) reported that the reduction in tranSpiration rate is caused by
interruption of the water supply to the tissue. ReSpiration increased
and then later decreased in oil treated plants according to three
reports (2h,b0,50). Minshall and Helson (SO) Observed that in suscept-
ible plants respiration after treatment with oil decreased to zero with
no recovery, while in the resistant plants respiration decreased but

returned to normal. Knight, Chamberlin, and Samuels (hO) found that,

in plants treated with oil, photosynthesis was stopped immediately.
Minshall and Helson (50) found that photosynthesis was stepped in
susceptible plants that were sprayed with oil and in high light intens-
ity the chlorophyll was rapidly broken down. The theory was advanced
that the interruption of the supply of water was responsible for the
cessation of photosynthesis (15,31,50). Dallyn and Sweet (15) added
the idea that oils may cause a mechanical interference with gas exchange
necessary for photosynthesis. Minshall and Helson (50) reported that
the amount of oil influenced the degree of photosynthesis stoppage.

The theory that photosynthesis is stopped by the rupture of the mem-
branes of the chloroplasts has been advanced by Dallyn and Sweet (15)
and van.0verbeek and Blondeau (80).

Currier (13), Dallyn (1t), and van Overbeek and Blondeau (80) have
found that the semi-permeable membranes in the cells have been made
permeable by treating with a toxic oil. Van Overbeek and Blondeau (80)
proposed the theory that the plasma.membranes consist of a lipoid
fraction and a protein fraction. The lipoid fraction is composed of
two layers of lipoid molecules with their polar ends together and the
lipoid layers are surrounded by protein molecules. Toxic oils, accord-
ing to this theory, act to disrupt the lipoid fraction and render the
membranes permeable. Numerous reports stated that oil injury is
associated with an interference of water transfer in the tissue (10,1b,
lS,31,h9,SO). Dallyn (lb) and Helson and Minshall (31) observed that
oils have altered the action of stomata. Dallyn (1L) further observed

that oil injury allowed the entry of a fungus into plant tissue.

Several ideas have been advanced with respect to reasons for
selectivity of oils. Because most members of the Umbelliferae family
have a high natural oil content and because the family is notably
resistant to oils, the theory has been advanced that the presence of
the natural oils render the plant resistant to toxic oils (15,29).

That the natural oils may dilute the toxic oils or that the natural oil
ducts may act as reservoirs for the toxic oils have both been mentioned
as possible methods of providing resistance by Havis (29). Dallyn and
Sweet (15) suggested that the resistance that has been shown by carrots
and parsnips may be caused by the thick compact parenchyma that sur-
rounds the vascular core. Crafts (10) stated that resistance to oil
was caused by a difference in the protoplasm of resistant and suscept—
ible species. Currier (13), Dallyn and Sweet (15), and van Overbeek
and Blondeau (80) have suggested the reasons for selectivity as being
a difference in the composition of the plasma membranes.

Environmental factors influence the amount of injury obtained by
treatment of plant tissue with oil. it low'temperature less injury
occurred according to Eliason (18), but Dallyn (It) found temperature
may affect only the speed of injury. Low humidity leads to greater
injury and at low light intensity less injury was observed by Dallyn
and Sweet (1h,15). Dallyn (1h) also observed that hardened plants and
starved plants exhibited more injury than normal plants when treated
with oil. Currier (13) described characteristic injury on plants as
a darkening of tips of the youngest leaves due to a leakage of sap into

intercellular spaces. The darkening spread to the older leaves and was

followed by a loss of turgor and drooping of stem and leaves. The
plants exhibited strong odors similar to that of macerated tissues.

In bright sunlight chlorophyll was destroyed, sometimes resulting in
complete bleaching of the affected portions. Addicott (l), and Minshall
and Helson (h9) described injury to leaf tissues as a collapse and
shrinkage of the entire cell, including the cell wall and, later, a more
or less complete cytolysis.

The application of oils prior to planting (ll), pro-emergence
(2,11,30,32,h3,52,65,87), and post-emergence treatments have been re-
ported in numerous papers. Post-emergence sprays have been used as
selective Sprays on tree nursery seed beds (8,18,19) and on crops in
the Umbelliferae family (2,10,h2,7h). Eliason (18) mentioned an increase
in injury when pine seedlings were sprayed when the soil moisture was
low and the seedlings exhibited reduced turgor pressure. Lachman (DZ)
reported that oils were more toxic in carrot fields when the plants were
wet.

Post-emergence oil sprays have been.used in crops as directed
sprays. Wboten (88) designed a floating spray shoe with a laterally
directed nozzle whinh placed the herbicidal oil at the base of the stems
of the crOp being sprayed. Other reports mentioned the use of Spraying
equipment very similar to Wboten's design (50,77,91). Efilson and
Bruner (85,86) used directional Spray equipment that employed a float-
ing shield to protect the crop plant. They Obtained good weed control
using this equipment on snap beans. Shielded nozzles have also been

used on batons (57). Directed sprays can be used on plants when a

10

certain region of the plant is more resistant. The waxy covering on

the stem of the cotton plant renders them more resistant to herbicidal'
oils (60,75). Mueller and Loomis (51) stated that 1eaves.and herbaceous
stems are covered with a special protective layer a few microns thick,
known as cuticle. They further stated that the cuticle is assumed to

be composed of pectin, a group of waxes known collectively as cutin,

and possibly some cellulose. Many plants show an accumulation of various
waxy materials on the surface of the cuticle. This resistant cuticle

on the stems of plants has been the subject of much directed Spray
research.

Antognini (h) used herbicidal oils as a stem spray on onions.
Hardcastle and Stamper (27) used herbicidal oils as directed sprays on
sugar cane but they obtained injury. Talley (75) reported that low
volumes of herbicidal oils could.be used as directed sprays on cotton.
McWhorter and Holstun (b8) obtained good weed control with five gallons
per acre of herbicidal oil applied to the base of the cotton stems in
a band eight to ten inches wide on rows planted forty inches apart.
‘Williams and Hinkle (83) observed injury when nine gallons per acre of
a herbicidal oil was used on cotton. Ratcliff, gt 3.1.. (61) obtained
injury when a herbicidal oil was used at ten gallons per acre as a
directed spray on cotton. Most workers (h8,60,6l,75) agree that
herbicidal oils should be applied early to cotton in order to obtain
good weed control with a minimum of injury to the crop. McWhorter and
Holstun (ha) and Talley (75) reported that oils can be applied to

cotton five days after emergence. ‘McWhorter and Holstun (b8), Palmer

11

and Ennis (55), and Ratcliff, it 31. (61) reported that injury will
occur if herbicidal oils are applied to cotton after bark forms on the
stem. Holstun et_§1, (33,3h) found that certain varieties and hill
planted cotton gave less injury from oil treatments. Several reports
(33,71,83) stated that oils applied by directing the nozzles parallel
with the rows of cotton gave less cotton injury than nozzles directed
across the rows'but they obtained less weed control (33,83). Holstun,
23 21. (3h) reported that the best weed control was obtained with
herbicidal oils when the cotton was grown on beds approximately two
inches high. -Talley (75) found that the petroleum naphthas gave the
best results on cotton of the herbicidal oils. Both the aromatic con-
tent (3h,75,76) and the naphthenic content (75) is important in 8
herbicidal oils. Talley, gt filo (76) obtained poor weed control when
they used hexane. Numerous reports (9, 58,62,63,6h,7l,75) indicated
that satisfactory weed control was obtained by using several different
oils. The use of herbicidal oils in pre- and post-emergence combinations
have shown.promise in cotton (9,26,h8,53,63,82,8h). ‘Williams and Hinkle
(83) obtained better grass control in cotton by fortifying the herbicidal
oil, but no better broad leaf weed control. Fortifying oils have shown
little promise for use in cotton (33,3h,75).

Leonard and Harris (hh,h5,h6) reported several experiments con-
ducted in the greenhouse and in the field with directed oil application
on soybeans and cotton. They found that the hypocotyls of cotton and
soybeans were more resistant to oils than the stems of grass (hS).

Soybean hypocotyls were somewhat resistant to oils but they were more

12

. susceptible than cotton hypocotyls (hS). VM&P Naphtha (boiling range
250° - 2900 F.) selectively removed small annual weeds when applied at
the base of the stems of soybeans at the rate of two and one-half
gallons per acre to a narrow band in the rows planted forty inches
apart (h5). Octane also gave good weed control with no soybean injury
(b5). Lion Herbicidal Oil No. 1 gave some injury when applied at seven
gallons per acre to soybeans (hb,h6). Young soybean plants showed
little injury from one application of 12.5% and 25% benzene, toluene,
xylene, and trimethylbenzene in dispersol (hh). 01d soybean plants
showed less injury than the young plants and withstood two applications
of the aromatic oils (bk). Aliphatic oils in the six to ten carbon
range caused a burning of the hypocotyl, the severity of which increased
as the number of carbons increased (hh). Dodecane caused most injury
at the base of the hypocotyl (hh).

Peek:and Hinkle (56) applied a herbicidal oil to soybeans as a
epray directed at the base of the stems. They sprayed a ten inch band
in the forty inch rows at five gallons per acre. The first application
was applied fourteen days after emergence. Two applications gave
excellent weed control without serious bean damage.

Smith and Slife (68) applied herbicidal oil to soybeans in the
first trifoliate leaf, fourth trifoliate leaf, and eighth trifoliate
leaf stage in 1953. The soybeans were treated with five, seven and
one-half, and ten gallons per acre applied in a narrow’band in the
forty inch rows. Two areas of the bean stem were used as application

points: ground level, and between the primary leaves and the first

13

trifoliate leaf. High placement of the spray gave the most damage.
The fourth trifoliate leaf stage exhibited the most injury. Less injury
and better weed control was obtained with the early treatment. There
was no significant difference in yields between treatments. Stem burn-
ing, killing of the plants, and lodging were the characteristics of oil
injury. In.l95h, Smith and Slife (70) tested the same herbicidal oil
at the same rates but applied them at the first trifoliate leaf, third
trifoliate leaf, fifth trifoliate leaf, and seventh trifoliate leaf
stages. Injury was about the same at the different stages of growth but
recovery was better when the plants were treated early. Ten gallons of
oil per acre caused more injury than the lower volumes. They recommended
that oil sprays be applied one to two weeks after planting. Less bean
injury and better weed control was obtained at this time of application.

Chappell and Camper (6,7) used Stoddard solvent at five gallons
per acre as a directed band spray on soybeans. They obtained little
weed control and no injury to the soybeans.

Upchurch (79) applied twenty gallons per acre (broadcast rate) of
a herbicidal oil as a directed band Spray on scybeans twenty days after
planting. He obtained good weed control. A single oiling plus one
cultivation gave the highest yield. One, two, and three oilings Spaced
one week apart gave good weed control without appreciable soybean
injury.

Sweet, 23 §l° (72,73) used various herbicidal oils as directed
band sprays on snap beans, lima beans and field beans. They used twenty-

five and fifty gallons per acre (broadcast rate) applied five weeks

1t

after planting. Good weed control was obtained with no difference in
yields. When four applications were applied three days apart, a
reduction in yield was Obtained; however, when the interval was five
days no reduction in yield occurred. They found that when the epider-

mis was killed the injury never penetrated beyond the phloem.

15

MATERIALS AND METHODS

Herbicidal oils furnished by the Standard Oil Company of Indiana
were used in various tests in an attrmpt to find an oil that was
relatively non-toxic to the stems of bean plants but was still suffici-
ently toxic to kill weeds. A list of the various experimental oils
used and the available information on their components and preperties
is given in the appendix, page 69.

Several small screening tests were conducted in the Plant Science
Greenhouse at Michigan State University during the winter of 1952-53.
The undesirable oils were drOpped from further tests while the desir-
able oils were carried on through several series of tests. The screen-

ing test consisted of growing soybean (glycine max, variety Hawkeye)

 

and field bean (Phaseolus vulgaris, variety Michelite) plants in pot

 

culture. Three plants were grown per pot in unsterilized clay loam
soil. The oils were applied to the surface of the soil in the pot and
one inch of the stem of each bean plant at rates of one and two milli-
liters per twelve inch pot. A small DeVilbis sprayer was used to apply
the oil. This same type of Sprayer is used in entomological studies

in the Peak-Grady test for toxicity of insecticides. (Air was supplied
to the Sprayer from a three gallon compressed air sprayer tank. The
Sprayer was rinsed between treatments with 95% ethyl alcohol. The oils
were applied when the first trifoliate leaf had emerged on the test

plants. Ratings were made on the toxicity of the oil to the bean plants

l6

and on the weeds present three weeks after Spraying. The rating scale
used was: 1 - no injury, 12 - complete kill.

1 power driven Sprayer was modified so that herbicidal oils could
be applied as directed-Sprays to the base of the stem of been plants
under field conditions. A Planet Jr. 1 1/2 horsepower garden tractor
was used for the power unit. .L l/h inch Oberdorfer gear pump with a
pressure regulator and pressure gauge was mounted on the front of the
tractor and a Vebelt was used to transfer the power from the engine to
the pump. A one-gallon can was mounted on the front of the tractor for
the spray solution tank. Two nozzles were arranged on the cultivator
shanks behind the tractor and were connected to the pump unit by l/h
inch Neaprene hose. The nozzles could be rotated in all directions and
adjusted for height. Two free-floating shields made of 20 gauge galvan-
ized sheet metal, mounted on a forward runner and a rear runner, were
attached to the cultivator shanks to stand between the nozzles and the
bean plants. The front of the shield was two inches and the rear of
the shield one inch above the ground. The fan type nozzles were di-
rected to spray horizontally underneath the shields into the row so
that the Spray pattern from one nozzle did not interfere with that
from the opposite nozzle. .A 6 inch band in the row was sprayed as well
as about 1 inch of the lower part of the bean stem. The Sprayer was
rinsed out with 95% ethyl alcohol between treatments. Photographs of
the sprayer are in the appendix, figures 17, 18, and 19.

Field tests were conducted on.the Botany Department plots at

East Lansing, Michigan in the summer of 1953. The clay loam soil was

l7

plowed and disced on June 9, 1953, and soybeans, field beans, lima
beans (Phaseolus lunatus, variety Fordhook Dwarf), wax beans (Phaseolus ‘
vulgaris, variety Pencil Pod Max), and green beans (Phaseolus vulgaris,
variety Tendergreen Bush) were planted in 22 inch rows on June 10, 1953,
with a small garden drill. Two rows of beans were planted for each
treatment and the rows were divided into 3 plots, 2 rods long. Nine
herbicidal oils that showed promise in the previous screening tests, or
otherwise indicated that they could be used on beans, were applied with
the power sprayer. Nozzles with teejet tips, size 730067, were used
with 20 pounds per square inch pressure and the power sprayer traveled

° at about 2 miles per hour whicklapplied 10 gallons per acre. Rates of
application, in gallons per acre, expressed in this report are based

on 6 inch band treatments in 22 inch rows. The oil Sprays were applied
on July 7, 1953, when the beans had developed their second trifoliate
leaf and some of the weeds were two inches high. The soybeans were
sprayed the second time on July 18 when the sixth trifoliate leaf had
developed and the plants were about 1h inches high. The soybeans were
cultivated on June 30 and again on July 7 while the other beans were
cultivated only once, on July 18. Counts of grasses and broad-leaved
weeds were made in the field, lime, wax, and green beans on July 25.
Heed counts were made in a h inch band on 100 inches of row in 2 rows

of each plot. All plots were hand-heed to remove the weeds after the
weed counts were completed. Observations on the effect of the oil upon
the beans were made throughout the growing season. Pieces of stems

that had been treated with oil were randomly selected from each plot

18

fixed, sectioned, stained with Conant's quadruple stain and examined
under the microsc0pe for anatomical injury. Photomicrographs were made
of some of the sections which had oil injury. Yield data were taken
from all plots. Four pickings were made on the wax and green beans and
two pickings on the lima beans. Two replications were harvested from
the field beans because the third replication was flooded out at harvest
time. One treatment in the field beans was removed accidently and thus
the yield data were not available.

Field beans were drilled in, August 6, 1953, on muck soil, located
near East Lansing, Michigan, that previously had been disced and floated.
Two rows were planted per treatment and each treatment was divided into
three replications. Twelve herbicidal oils were applied at a rate of
10 gallons per acre with the power sprayer as a directed basal stem
Spray on.Lugust 27, when the beans had develOped one trifoliate leaf.

A second treatment was applied on September 3 to those plots that showed
no oil injury on the beans but still had weeds in the treated area. The
beans had three trifoliate leaves at this spraying. Bean and weed
injury ratings and weed counts were made on September 1h.

Observations made of the effect of oils on vegetation grown under
field conditions, when compared with observations of the effect of oils
on vegetation grown under greenhouse conditions, indicated that screen-
ing tests under greenhouse conditions were not reliable. Therefore, a
field screening test was set up on the muck soil plots. Field beans,

lima beans, wax beans, and green beans were planted in 22 inch rows on

August 6, 1953 with a small garden drill. Nineteen different herbicidal

l9

oils were applied to each kind of bean with the DeVilbis sprayer, on
August 27, when the beans had deve10ped their first trifoliate leaf.
Five milliliters of the oil were used for each treatment. The sprayer
was hand directed and the oil applied to a.3 inch band in the row and
1 inch of the bean plant stem. Each treatment was applied to at least
3 bean plants. Bean and weed injury ratings were made on September 10.

Greenhouse tests were conducted in the winter of 1953-5h. Soy-
beans were planted in 12 inch pots in steam sterilized, sandy loam soil
on December 16, 1953 and later thinned to three bean plants per pot.
The experimental oils that had shown promise in the field tests were
applied with the DeVilbis sprayer on December 30 to 3 randomized repli-
cations. Twenty gallons per acre of the herbicidal oils were applied
as a basal stem treatment. The bean plants were harvested by cutting
the stem at the ground line and drying the entire above-ground.portion
of the plant in a drying oven for 2 days before weighing. Bean injury
ratings were made prior to harvest on February 6, l95h.

Soybeans were planted in unsterilized clay loam soil in 12 inch
pots on January 23, 195h for an oil screening test. The same methods
were used as were described in the previous test. Seven oils were
applied on February 13. Bean and weed injury ratings were made and the
number of plants surviving was recorded before the beans were harvested
and dry weights detenlined on.March 20.

Two tests were conducted in the greenhouse to determine the stage
of growth that was least susceptible to oil injury. Soybeans and
field beans were seeded in 12 inch pots on March 6, l95h in an

unsterilized clay loam soil. The bean plants were thinned to three

20

plants per pot before treatment. Three experimental herbicidal oils

at a rate of 20 gallons per acre were applied with the DeVilbis sprayer
to the stems of the bean plants and surface of the soil at different
stages of growth. Applications were made on.March 13 (3 days after
emergence), March 23 (first trifoliate leaf), and April 2 (third tri-
foliate leaf). One series of pots received an application on all three
dates. Bean injury ratings were made and the number of plants surviving
was recorded before the beans were harvested and dry weights were
detennined on April 22.

Soybeans were planted in 12 inch pots on February 7, l9Sh, in
unsterilized sandy loam soil. LS-0237 was applied 0, 3, 6, 13, 19, 27,
and 32 days after emergence of the bean plants at 20 gallons per acre
to pots containing h plants each. The standard greenhouse screening
procedure used in the other tests was used. The 3 randomized replica-
tions were rated for oil injury and the dry weights were determined on
April 8, 195b.

.A test was conducted to determine if the amount of oil applied or
the temperature at the time of application affected the amount of injury
obtained. Soybeans were planted in an unsterilized clay loam soil in
12 inch pots on January 31, 19Sh. The plants were grown.under green-
house conditions (68°-7o° r.) until they had developed the first tri-
foliate leaf. At this stage they were randomly divided into groups of
12 pots and transferred to greenhouse areas of 60, 70, and 800 F.
temperatures. The pots remained in these temperature areas for 2 days

before they were sprayed with the herbicidal oil. The DeVilbis sprayer

21

was used to apply 20, 30, and hO gallons per acre of LS-O237 to the
surface of the soil and base of the stems of the soybean plants on
February 13. The treatments were randomized in triplicate. The soybean
plants remained in the temperature areas for 18 hours after spraying
before they were returned to regular greenhouse conditions. Injury rat-
ings and observations on the surviving plants were made 3 weeks after
treatment. The soybeans were harvested and dry weights determined on
March 20.

Repeat application of oils on beans was tested in the greenhouse.
Soybeans were drilled in 22 inch rows in a clay loam soil in a greenhouse
bed on January 11, l95h. The rows were divided into 3 replications.

A Spray boom was built with drop nozzles to direct the Spray horizontally
at the base of the bean stems. The boom was attached to a 3 gallon
compressed air sprayer. The operator moved the boom sprayer slowly
enough to thoroughly wet the bean stems. The first treatment of herbicidal
oil LS-O237 was applied on January 31 after the beans had developed

their first trifoliate leaf. Additional treatments were made one week
apart on some of the rows until 1, 2, and 3 treatments had been applied
to similar rows. Two weeks after the last treatment injury ratings were
made. Six bean plants were randomly selected from each treatment
replication on March 6 and tested for stem strength and later dried and
weighed.

An apparatus was designed and built to measure the resistance to
bending that the bean stems possessed. Three inches of the plant stems

were cut from the bean plants and were clamped to a flat surface with

22

1 1/2 inches of the stem extending beyond the edge of the clamp.

A protractor was mounted behind the clamp with the center located at the
edge of the clamp. A crossarm with two small pulleys attached was sus-
pended above the clamp. .A string with a bottle attached to one end was
run through the pulleys and tied to the free end of the bean stem.'

water was added to the bottle until the bean stem was bent in a 90 degree
angle from its original horizontal position. Two observations were made
with this apparatus: (1) Number of grams required to bend the stem 90
degrees; (2) the resilience in degrees from the original position the stem
exhibited one minute after the weight was released. .A drawing of this
apparatus is in the appendix, figure 20.

In the summer of l95h additional field tests were made. The 3 tests
made were a field screening test, a rate of application test, and a time
of application test. The general methods were the same for all of these
tests and very similar to the field tests conducted in the summer of 1953.
The 5 kinds of beans were drilled in on the Botany Department plots in
22 inch rows on a clay loam soil that had been plowed, disced, and dragged
1 day before planting. Each treatment consisted of 2 rows which were
divided into 3 replications 1 rod long. The oils were applied with the
power Sprayer used in the 1953 field tests and the oils were directed at
the base of the bean.plant stems. ‘Weed counts were made on July 1 on
the screening and rate tests by counting the weeds present in h inches
of the treated band in two 100 inch sections of row for a total of 200
inches of row per plot. All plots were cultivated on July 1 and hand

hoed July 2-8. Treated stems were randomly selected for sectioning in

23

all of the plots on July 25. The sections were fixed in Farmer's fixa-
tive, sectioned, and stained with Conant's quadruple stain and examined
under a microscope for anatomical oil injury. Observations on the oil
injury were made on August 29. Yields were taken from the soybean and
field bean plots by weighing the dry beans. Yields were taken from the
lima, wax, and green bean plots by taking the green weight of the 3
pickings that were made.

The field screening test was planted on June 7 and Sprayed on June
‘ 23, when the bean plants had developed their first trifoliate leaf, with
7 different oils. One treatment consisted of spraying on June 23 with
LS-0237 followed by another apolication on July 1. Ten gallons of oil
per acre were applied.

The rate of application tests were planted on June 9 and sprayed
on June 23 when the bean plants had just developed their first trifoliate
leaf. The herbicidal oil LS-0237 was used in all of the treatments.
Five, ten.and twenty gallons per acre were applied by using Teejet tips
sizes 730038, 730067, and 8001 respectively with 20 pounds pressure per
square inch and traveling at about 2 miles per hour.

The time-of—application plots were planted on June 7 and sprayed
at different stages in the growth of the bean plants. Herbicidal oil
LS-0237 was used in all of these tests at 10 gallons per acre. The oil
Sprays were applied on the following dates: June 15 (first true leaf),

June 23 (first trifoliate leaf), July 1 (third trifoliate leaf), and

July 21 (budding and blossoming). In addition, one plot received an

application on'both June 15 and June 23.

2h

Further testing was conducted in the Plant Science greenhouse in
the winter of l95h-55. Soybeans, field beans, lima beans, wax beans,
and green beans were planted in 12 inch pots in unsterilized clay loam
soil on January 1h, 1955. Five eXperimental oils that had given good
results in the field tests were applied with the DeVilbis sprayer at 20
gallons per acre on January 28 when the beans had develOped their first
trifoliate leaf. Each treatment was made in triplicate and randomized.
One day before treatment the bean plants were thinned to four plants
per pot and after treatment the soybean, field beans, and lime bean
plants were thinned to three plants per pot while the wax and green
bean plants were thinned to 2 plants per pot. ‘Weed and bean injury
ratings were made on February 5. Photographs were taken of some of the
stems showing oil injury. The bean plants were harvested on March h by
washing the soil away from the roots of the plants with running water.
The stem was cut off at the soil line and dry weights of the stems and
roots were determined. The nodules on the roots of the green bean
plants were counted.

On.February 1h, 1955, soybeans were planted in unsterilized clay
loam soil in 12 inch pots. Prior to treatment the plants were thinned
to six plants per pot. When the plants had deve10ped their first tri-
foliate leaf, the pots were randomly divided into 2 groups. One group
of pots remained under ordinary conditions but the other group was placed
under a fluorescent lamp about h300 P.M. on March 7. The fluorescent
lamp did not increase the temperature of the air but gave light condi-
tions comparable to daylight. At 10:00 P.M. on March 7 the plant stems

were Sprayed with herbicidal oil LS-0237 at 20, to, and 60 gallons

25

per acre. The oil was applied with the DeVilbis sprayer and each treat-
ment was randomized in 3 replications. The epidermal cells of the stems
of some of the plants under the light and dark conditions were stripped
off and emersed in absolute ethyl alcohol. These strips were later
examined under the low'power lens of a microsc0pe to check the size of
the stomata opening. The light was removed from the pots 1/2 hour after
treatment and the pots were placed together and randomized 12 hours
later. Bean injury ratings were made on.March 12 and the number of sur-
viving plants was recorded. The number of plants in the 20 gallon per
acre treatments and check were reduced to 2 per pot on March 8. The dry
weights were determined for the surviving plants in the 20 gallon per
acre treatment and the check pots on April 1h.

The effect of the oils upon some weeds commonly present in bean
fields wes investigated in the greenhouse in 1955. LS~0237 was applied
at various rates to weeds growing in greenhouse flats. LS-0237 was
applied to the flats of weeds on.January 10, 1955. The oil was applied
at 5, 10, and 20 gallons per acre. The weeds varied from seedlings to
a maximum height of 1 inch. Weed counts were made on January 15. Five
other experimental oils also were applied to weeds grown in flats.

The oils were applied at 10 gallons per acre when the weeds were in the
seedling or first leaf stage, Weed counts were made on March 13.

In both of these experiments the weeds were grown from volunteer
seeding in unsterilized clay loam soil in 3 weeks. The oil treatments
were applied with the DeVilbis Sprayer. .All treatments were randomized
with four replications. Need counts were made by counting individual

Species in the entire flat.

26

EXPERIMENTAL RESULTS

The purpose of the oil screening tests made in the winter of
1952-53 was to find an oil that was not toxic to the stems of bean plants
but was toxic to weeds. Table I is a compilation of injury ratings
obtained from several small oil screening tests made on soybeans and
field beans. The tests indicated that field beans were more resistant
to oil stem sprays than were soybeans. The oils, LS-0132, LS~0133,
LS-Ol50, LS-0151, LS-0152, LS-0153, L-63l9, and L-7565 gave quite severe
injury and were dropped from further testing at that time. Oils LS-Olh7,
LS-OlSh, LS-0155, LS-Ol78, L-3388, L-6581, L-7710, L-7718, and L-8712
appeared to be less injurious to the stems and were investigated further
as to their weed injury ratings. A new lot of L-3388 gave less injury
than a year-old sample and consequently, new samples were used on all
further testing. L-87l2 was not toxic on weeds.

Typical oil injury on the bean.p1ants was characterized by a wilt-
ing of the entire plant similar to a plant suffering from the lack of
water. The leaves were wilted and the stems were weak. The treated area
of the stem had a water soaked appearance. If the plant was not killed
by the oil, the stem tissue in the treated area was severely browned and
the plant appeared to be slightly stunted. Some of the oils caused a
slower reaction on the plant and little injury was noted until h days
after treatment. A few of the heavier oils produced injury only at the

ground line.

27

TABLE I

INJURY RATINGS MADE ON SOYBEANS, FIELD BEANS, AND WEEDS
‘FOLLOWING.APPLICATIONS OF HERBICIDAL OILS
AS BASAL STEM TREATMENTS

 

 

 

 

Oil Used Bean Injury;Rating} weed Injury'Ratingl
Soybeans Field Beans .

LS-0132 12 h

LS-Ol33 12 10

LS-Olh? 7 , 2.7 , 11.2
LS-OlSO 12 8

LS-0151 9 5

LS-0152 12 11

LS-0153 12 12

LS-OlSh 2.7 11 7
1.3.0155 h.2 h.3 I 10
ILS-0178 ' b.5 1.7 6.5
L-3388 (new) 7 3.3 9.8
L-3388 (old) 6.5 7 12
L-63l9 10 10 12
L-6581 2 3.5 9.5
L-7565 12 5

L-7710 5.5 3 11
L-7718 3.5 3 10.5
L-8712 3 3 3

 

J”Injury ratings: 1 - no effect, 12 - complete kill.

28

Because of the limited time and space available for field work,
only the best oils from the screening tests were used in the field tests
in the summer of 1953. Some additional oils that had shown promise for
other workers were obtained for field testing. Octane (LS-0235) and VM&P
naphtha (L—6580) had been mentioned by Leonard and Harris (uh,t5) as
promising oils for weed control in soybeans. A very toxic oil, L-7297,
was included in the field test. Bean yields obtained after the various
oils were applied to 5 kinds of beans in the 1953 field tests as directed
sprays at the base of the stems of the bean plants are presented in

Table II. A significant reduction in yield occurred only when LS-Olb?

TABLE II

YIELDS OBTAINED FOLLOWING APPLICATION OF HERBICIDAL OILS

 

 

Oils Used

 

 

 

_f_ ____ Yield in Pounds Per'Acre

Soybeanl Field Bean LimaIBean Green Bean wax Bean
LS-01h7 2050 926 1889 2926** h296
LS~015b 2350 778 1667 6037 3778
LS-0155 2250 963 2111 h333 h630
Ls-Ol78 2250 630 1222 6889 h556
LS-0235 2350 778 1185 5778 L667
LS-0237 2300 1037 1852 5778 5296
L-6580 2350 1111 1630 6111 507u
L-7297 2250 --- 1815 6815 3815
L-7710 2000 963 1889 h37o h556
Untreated 2350 519 926 5852 <363O
LSD 1% 2781
LSD 5% 2000

 

ITwo applications of oil were made on all soybean plots.

29

was applied to the green beans. This probably can be attributed to
experimental error because no injury was noticed on the bean plants
during the growing season. Observations made after the oil was applied
indicated that moderate injury occurred in all of the plots that had
been sprayed with L-7297. Later in the season many of the stems in the
L-7297 plots broke off at the ground line. L-7710 caused slight injury
in all of the plots and some of the stems were very weak at harvest.
LS-0237 gave slight injury to the stem of lime and green beans.

Some injury was noted in the examinations of the cross sections
of the treated stems. Surface injury was noted in several of the sections
and was characterized by causing a break-down of the cells in the epidermis
and cortex. The cells adjacent to the injured cells reverted to meriste-
matic activity and a periderm layer was formed around the injured tissue.
Internal injury was noted in a few of the sections and was characterized
by a breakedown of the cells in the epidermis, cortex, phloem and
vascular Cambium. The cells adjacent to the injured tissue reverted to
meristematic activity and a protective layer, similar to a periderm, was
formed. Photographs of this injury is shown in the appendix, figures
5-15. Surface injury was Observed when L-7710 and L-7297 was applied to
all 5 kinds of beans. LS-OlSh, LS-O237 and L-6580 caused slight surface
injury when applied to the lima, wax and green beans. Internal injury
was observed in the soybeans, field, and green bean stems when L-7297
and L-77lO were used. Internal injury was also noted in the green bean

stems when LS-0237 was used.

30

Table III gives the results of the weed counts made on the 1953
field oil screening tests. The main grasses present were green foxtail

(Setaria viridis (L.) Beauv.), yellow foxtail (Setaria lutescens (Heigal)

 

F. T. Hubb), large crabgrass (Digitaris sanguinalis (L.) Scop), and barn-

yard grass (Echinochlos crusgalli (L.) Beauv.), The main broad-leaved

 

weeds present were lamb's quarters (Chenopodium album L.), pigweed

(Amaranthus retroflexus L.), and purslane (Portulaca oleracea L.).

TABLE III

NUMBER OF WEEDS FOLLOWING APPLICATION OF HERBICIDAL OILS

Number of Needs Per Square Foot .

 

 

 

 

 

Field Bean Lima Bean Green Bean wax Bean
Oil Used Grass Broad- Grass Broad- Grass Broad- Grass Broad-

. leaf leaf leaf leaf
1.3.01u7 0.7 7.5” 1.0 8.5H 2.6 18.6 0.5“" 7.5”
LS-OlSh 0.8 18.2 0.8 23.2 .6 17.5* 2.1** 21.8
LS-cuss 0.2* 8.6" 0.6 7.5” 1.0 7.9 0.7“ 6.14H
LS-0178 2.h l6.8* 0.h 21.7 .5 16.h* 0.7** 18.2**
LS-0235 0.2* 15.l** 0.8 17.1* .2 12.5** 0.5 16.8**
1.8-0237 0.0* 5.7“ 0J4 3.3” .7 5.7M 0.1” 3.6“
L-6580 0.0* 7.1** 1.2 8.8** .2 6.1** o.8** 5.7**
L-7297 - 0.0 ht” .7 3.2“ 0.0“ 5.7“
mm 0.1? M” 1.0 2.t** .6 5.1;“ 0.5“ to”
Untreated 1.7 23.2 3.3 29.h 1.1 27.1 5.2 28.6
LSD 1% 1.8 7.3 13.1 11.9 2.3 9.h
LSD 5% 1.3 5.3 9.5 8.7 1.6 6.8

 

The number of grasses per square foot was not Significantly different
between treatments in the lime and green bean plots. The lack of a

Significant difference is probably due to the low grass population in

31

all of the plots and the germination of most of the grasses after
treatment. The number of grasses per square foot showed a significant
difference between treatments in the field and.wax bean plots. All
treatments were significantly lower than the untreated except in the
LS—Olh7, LS-OlSh, and LS-Ol78 treatments applied to the field beans.
The number of broad-leaved weeds per square foot showed a highly sig-
nificant difference between treatments in all h kinds of beans. .All
treatments except LS-OlSh and LS-0178 gave a highly Significant decrease
and LS-Ol78 gave a significant decrease in the number of broad-leaved
weeds compared with the untreated plots in the field beans. All treat-
ments except LS_015h, LS—Ol78, and LS-O235 gave a highly significant
decrease and LS~0235 gave a significant decrease in the number of broad-
leaved weeds compared with the untreated plots in the lima beans. All
treatments except LS-Olh7, LS-OlSh and LS-Ol78 gave a highly significant
decrease and LS-OlSh and LS-Ol78 gave a significant decrease in the
nmmber of broad—leaved weeds compared with the untreated plots in the
green beans. All treatments except LS-OlSh gave a highly significant
decrease in the number of broad-leaved weeds compared with the untreated
plots in the wax beans. LS~O237, L-7297, and L-77lO gave the greatest
and most consistent decrease in the number of broad-leaved weeds of any
of the oils and this is significant in comparing them with Ls-015h,
LS-Ol78, and LS-0235 in.most of the comparisons.

Further field trials were conducted with field beans using the power
Sprayer on.muck soil to determine the effects of oils on different weed

Species and also the effects of the other oils on the bean stems.

32

Table IV shows the results of the injury ratings made and the number of
weeds per square foot after basal stem treatment of field beans with

12 herbicidal oils applied at the rate of 10 gallons per acre. The most

TABLE IV

NUMBER OF WEEDS.AND BEAN INJURY RATINGS FOLLOWING
APPLICATIONS OF HERBIDICAL OILS

 

 

 

 

 

Number Beanl Heedl Number of Weeds Per
Oils Used of Injury Injury Square Foot
Treatments Rating Rating Grass Broadleaf
LS-Olh? 2 2 8 1 .1“ 17 .6“
1.3.0153 2 2 7 11.8% 22 .9**
LS-OlSh 'l 3 8 S.2** l3.1**
LS-Olss 1 h 10 1.5% 5.8%.“:
LS-Ol78 2 2 2 9.0** 53.0
LS-0235 2 l 6 '3,7** 27.0**
LS-02 37 2 1 8 2 . 5% 1b ,5“
LS-0238 2 . 1 6 5.7** 2h.2**
L-3388 2 2 5 5.h** 36.7
L-6580 2 1 8 3.3** 12.1**
L-7297 1 6 9 3 .3W 5 .14“
L-77lO 2 5 10 1 .0“ h .5**
Untreated 0 1 1 16 .9 148 . 2
LSD 1% b.5 19.6
LSD 5% 3.3 1h.5

 

1Injury ratings: 1 = no effect, 12 - complete kill

abundant grasses in the plots were tickle grass (Panicum capillare L.),

 

Kentucky bluegrass (Poa pratensis L.), and quack grass (Agrgpyron repens

 

(L.) Beauv.): and the most abundant broad-leaved weeds were wormseed

mustard (Erysimum cheiranthoides L.), ragweed (Ambrosia artemisiifolia

 

L.) lamb's quarters (ChenOppdium album L.) purslane (Portulaca oleracea L.),

 

33

common chickweed (Stellaria media (L.) Cyrill), and mouse-ear chickweed

 

(Cerastium vulgatum L.) . All treatments gave a highly significant
decrease in the number of grasses. The number of grasses was signifi-
cantly higher in the LS—Ol78 treatment than in treatments LS-Olh7,
ISFOlSS, LS-0235, LS-O237, L-6580, L-7297 and L-7710. All treatments
except LS-0178 and L-3388 caused a highly significant decrease in the
number of broad-leaved weeds. Oils LS—0155, L-7297, and L-7710 had
significantly less broad-leaved weeds than LS~0153, LS-0178, LS-0235,
LS-O238, and L-3388. LS-O235, LS-0237, LS-O238, and L-658O after 2
treatments caused no noticeable injury to the stems of the field beans
while all otter treatments caused injury. LS~015h, LS-0155, and L-7297
caused bean stem injury after only 1 treatment. The weed injury ratings
indicated that LS-Olh7, LS-0153, Ls-015h, 1.310155, LS-0237, L-6580,
L-7297, and L-77lO gave over 50% weed control.

Field screening tests with the manually operated DeVilbis Sprayer
unit were conducted to check the results obtained in the greenhouse test.
Table V gives the injury ratings obtained by applying the experimental .
oils to the stems of h kinds of beans and weeds under field conditions.
Oils 1.3.0132, 1.3.0151, L—66h0, L-68h0, L-7565, L-89h9, L-8950, and L-8951
did not give enough weed kill to be useful as herbicidal oils in beans.
Oils L-63l9, L-658l, L-6639, L-66hl, L-77l8, and L-793h caused excessive
stem injury on the beans. Oils LS-Ol33, Ls-0150, LS-0152, and L-8952 '
did not give excessive injury to the bean stems and gave good weed

control.

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35

In the winter of l953-5b greenhouse screening tests were conducted.
Table VI gives the dry weights and injury ratings obtained after basal
stem treatment of soybean plants with 8 herbicidal oils at 20 gallons

per acre. In pots treated with LS~0237 a significant increase in dry

TABLE VI

DRY WEBSHT.AND INJURY RATINGS FOLLOWING
APPLICATION OF HERBICIDAL OILS

 

 

 

 

Bean1 Dry weight
Oils Used Injury grams

Rating“; _per pot
LS-0133 2 3.5
ISFOlSO 8 3.1
LS-OlSZ 2 3 .h
LS-0237 h h.3*
LS-0238 3 3.0
1.468110 h 3 .o
L-793h 10 2 .6
L-8952 3 3.2
Untreated 1 2.h
LSD 1% 1.6
LSD 5% 1.1

 

1Injury ratings: 1 -:no effect, 12 - complete kill.

weight per pot was found but no other significant difference between
treatment dry weights occurred. LS-OlSO and L—793h gave considerable
injury to the stem of the bean plants while the other oils gave only
slight injury.

Another screening test was conducted in the greenhouse in the
winter of 1953-Sh. Table VII gives the dry weight per pot, number of

plants surviving and injury ratings obtained after basal stem treatment

36

of soybean plants with 7 herbicidal oils at 20 gallons per acre.
Treatments with LS-0133, LS-OlSO, LS-OlSZ, LS-0237, and LS~0238 caused

a highly significant decrease in the dry weight per pot. Extensive bean
injury was noted in these same treatments and all of these pots had
plants killed before they were harvested. Good weed kill was obtained
in all treatments; however, treatments with LS-OlSZ, LS-0237, and LS—O238

were outstanding.

TABLE VII

DRY WEIGHT, NUMBER OF SURVIVING PLANTS AND INJURY RATImS
FOLLOWING APPLICATIONS OF HERBICIDAL OILS

 

 

 

 

Number of Bean:L weedl Dry Weight
Oils Used Surviving Injury Injury Grams
Plants Rating Rating Per Pot
I-S-0133 3.0 6 9 3.7“
LS-OISO 3.3 3 9 5.6“
LS-0152 1.7 10 10 1.8%*
LS-O237 1.0 11 11 3.8a!
LS~0238 2.7 8 11 3.3**
L-68ho u.o 3 7 8.5
L-8952 h.0 5 8 10.2
Untreated h.0 1 1 10.5
LSD 1% b.52
LSD 5% 3.26

 

1Injury ratings: 1 - no effect, 12 =:comp1ete kill.

There seemed to be a difference between experiments in the amount
of toxicity'produced by an oil. Several experiments were made to investi-
gate the cause for increased toxicity in some tests in an attempt to

isolate the causes and adapt them to field experiments.

37

Table VIII gives the injury ratings, number of plants surviving,

and dry weights obtained after basal stem treatments with 3 herbicidal

oils were applied at 20 gallons per acre to soybeans and field beans

at different stages of growth and a repeat application.

According to

the injury ratings, the soybean plants appeared to be more susceptible

TABLE VIII

INJURY RATINGS, NUMBER OF PLANTS SURVIVING, AND DRY WEIGHTS

FOLLOWING APPLICATIONS OF HERBICIDAL OILS

 

 

 

 

 

 

 

 

Time of Spray- Bean Injury1 No. of Plants Dry‘weight
ing and Stage Rating Surviving_r Grams/pot
of Growth Oils Used Soy- FIEId Soy- Field Soy- Field
bean Bean bean Bean bean Bean
3 days after Ls-01h7 5 1 3 3 2.6 h.9
emergence LS-OlSS 7 2 3 3 2.6 5.5
(Unifoliate L-7710 8 2 3 3 3.6 h.3
leaf)
13 days after Ls-01h7 3 h 3 3 3.5 6.1
emergence ‘ L-7710 5 8 3 2 1.9 3.6
(lat trifoli- LS-OlSS 3 h 3 3 3.5 h.7
_§§e leaf)
23 days after LS-Olh? 3 h 3 3 2.0 1.6
emergence L-7710 9 12 3 O 1.2 0
(3rd trifoli- Ls-0155 2 h 3 3 1.8 5.3
ate leaf)
Sprayed on LS-Olh? 12 S 0 3 O h.5
all three L—7710 10 10 1 l .9 1.6
dates LS-OISS 3 h 3 3 2.1 h.6
Untreated Untreated 1 l 3 3 1.8 h.2

 

1Injury ratings: 1

no effect, 12 ==comp1ete kill.

38

to oil injury in the unifoliate leaf stage than were field bean plants
at a similar stage of growth. Soybean plants exhibited the least injury
when the oil was applied after the plants had developed their first and
third trifoliate leaves. The field beans were injured least when the
oils were applied before the plants had developed their first trifoliate
leaf.

The repeat treatments caused more injury to the soybean plants when
LS-Olh? and L-7710‘were used. L-7710 appeared to be more toxic than
LS-Olh? and LS-OlSS. L-7710 killed some field bean plants when applied
to the first and third trifoliate leaf stage of growth.

Table II gives the injury ratings, number of plants surviving and
dry weights per plant obtained when LS-0237 was applied to the stems of
soybean plants at 20 gallons per acre at different stages of growth.

The number of plants surviving and injury ratings indicate that the
plant becomes more susceptible to oil in the later stages of growth.
The plants appear to be most susceptible to Oil injury when they have
developed their first and second trifoliate leaves. The dry weights
per plant gave no significant difference between treatments.

The effects of varying amounts of oil and different temperatures
while spraying was investigated in greenhouse tests. Table I gives the
injury ratings, number of plants surviving and dry weights Obtained
when LS-0237 was applied at 20, 30, and to gallons per acre to soybean
plant stems in 60, 70, and 800 F. temperatures, under greenhouse con-
ditions. Injury ratings indicate that less injury occurred when the

oils were applied in 600 F. temperatures and that injury increased when

39

TABLE IX

INJURY RATINGS, NUMBER OF PLANTS SURVIVING AND DRY WEBSHTS
FOLLOWING APPLICATIONS OF LS-0237

 

Time of Spraying Bean Number of Dry Heights
and Injury Plants Grams
Stage of Grogth Ratingl Surviving Per Plant

 

Day of emergence

(Bow) 1 b.0 1.5
3 days after emergence
(beginning unifoliate

leaf) 2 14.0 1 .9
6 days after emergence
(Full Unifoliate leaf) 2 h.o 1.7
13 days after emergence
(First trifoliate leaf) 10 1,7 2.1
19 days after emergence
(Second trifoliate leaf) 10 1.7 2.1

27 days after emergence
(Beginning third tri-
foliate leaf) 8 3.3 1.6
32 days after emergence

(Full third trifoliate

leaf) 6 3
Untreated 1 h

Cow
NH
NW

0

 

No significant difference between yields.

 

1Injury ratings: 1 a no effect, 12 a complete kill.

the amount of oil was increased. The number of plants surviving indicate
greater plant kill at the higher temperatures. Dry weights obtained
indicate a highly significant difference between treatments and untreated
except when 20 gallons per acre was applied at 700 F. At the 60 and 700
F. temperatures to gallons per acre caused a significant decrease in

dry weights compared with the 20 gallon per acre rate. There was no

significant difference in dry weights per pot between temperatures.

ho

TABLE I

INJURY RATINGS, NUMBER OF BEANS SURVIVING AND DRY WEIGHTS
FOLLOWING APPLICATIONS OF LS-0237

 

 

 

 

 

 

Temperature Gallons Number of Dry Weights
While Spray- per Injury Plants Grams
ing Degrees F. Acre Ratings1 Surviving_ Per Pot
60 2o 6 3.3 h.9**
30 7 3.3 h.9**
h0 8 3.0 3.6**
Untreated 1 h.0 7.3
70 20 6 3.3 h.8
30 8 2.3 3.2**
to 11 1.3 2.0**
Untreated 1 9,0 6.0
do 20 8 2.7 3 0**
3O 10 2.0 2.7**
hO 9 2.7 3.2**
Untreated 1 h.0 7.3
LSD 1% 2.2h
LSD 5% 1.65

 

1Injury ratings: 1 - no effect, 12 . complete kill.

The effects of making repeated applications of herbicidal oils as
stem treatments on beans was investigated by applying oil on soybeans
planted in a bed in the greenhouse. Table XI gives the injury ratings,
dry weights per plant, grams required to bend the bean stem 90 degrees,
and the resilience (number of degrees from the original position that
stems returned to 1 minute after release from a 90 degree bend)
obtained when LS-O237 was applied 1, 2, and 3 times. The second

and third applications caused an increase in injury as can

hl

TABLE II

INJURY RATINGS, DRY WEIGHTS, STRENGTH AND RESILIENCE OF STEMS
FOLLOWING APPLICATION OF LS-O237

 

 

Number of Injury Dry weight Grams Required Resilience

 

Treatments Ratings1 Grams/Plant to Bend Stem Degrees from
90 Degrees Original Position
1 3 2.2 h6.2 12.5
2 6 2.1 52.3 12.2
3 8 2.2 39.3 15.3
Untreated 1 2.1 23.5 18.5

 

No significant difference between treatments in dry weight, grams
required to bend stem on degrees, or resilience.

 

1Injury ratings: 1 a no effect, 12 - complete kill.

be noted in the injury ratings. There was no significant difference in
the dry weights, grams required to bend the stem 90 degrees or the
degrees in the resilience test. The treated stems appeared to require
considerably more weight to bend them 90 degrees but the variability in
stems eliminated a significant difference. The treated stems appeared
to have greater resilience but this was not significant.

Further field testing was conducted in the summer of 195h with oils
that had shown promise in earlier field and screening tests. Table III
gives the yields per acre that were obtained from 5 kinds of beans
grown under field conditions and treated with 7 herbicidal oils directed
at the base of the stems at 10 gallons per acre. .A significant
difference between treatments was found in soybeans, field beans, lima

beans, and green beans but no significant difference in wax beans.

h2

TABLE XII

YIELDS FOLLOWING APPLICATION OF HERBICIDAL OILS

 

 

Yields in Pounds Per Acre

 

 

 

Oil Used Soybeans Field Beans Lima Beans wax Beans Green Beans
Ls-0133 1857 1286 571b** 5000 8786
LS-OlSO 1929 1357 571has 6000 6h29
LS-OlSZ 2000 1500 5571*s 56h3 9071
LS~OlSS 1857 1357 5786** Sh29 9929*
LS-O237 221b** 16h3* h07l 5571 871h
LS-0237+

LS-0237 221h** l6h3* h071 5571 9000
LS-O238 1020 1571* hsooe h029 9357*
LS~6580 2000 1357 571h** S357 9071
Check 1857 1286 2357 b357 7357
LSD 1% 327 357 2670 2671
LSD 5% 237 257 1021 1936

 

LS-0237 and 2 treatments of LS~O237 gave a highly significant increase

in yield over the untreated in the soybean plots.

LS-0237, 2 treatments

of LS~0237, and LS-O238 gave a significant increase in yield in the

field bean plots.

LS-0133, Ls-0150, Ls-0152, Ls-0155, and Ls-6580 treat-

ments gave a highly significant increase and LSNO238 gave a significant

increase in yield over the untreated lima bean plots.

LS—OlSS and LS-O238

treatments gave a significant increase in yield over the untreated in

the green bean plots.

The increase in yield probably was caused by a

decrease in yield in the untreated plots because of weed growth that was

either not removed entirely or not early enough by the cultivation and

hand hoeing.

Observations made after treatment indicated that some

h3

injury occurred when two applications of LS-0237 was applied to the
soybeans, lima beans, wax beans, and green beans. The lima beans were
the most severely injured. Slight injury was noted when LS-0238 was
applied to field, line, wax and green beans. Slight injury was also
observed when LS-0237 was applied in a single treatment to lime and
green beans. LS-0152 showed slight injury on wax beans.

Examinations of stem cross sections indicated slight surface burn-
ing on some of the beans in the 19Sh field treatments. The soybeans
were injured slightly in the LS-O238 plots. The field beans were
injured slightly in the LS-6S80 plots. The lima beans were injured by
the LS-0133, LS-OlSZ, LS-OlSO, LS-0237, LS-0238 and LS-6580 treatments.
The wax beans were injured with LS-Ol33, LS-OlSO, and LS-6580 treatments.
The green beans were injured when LS—Ol33, LS-OlSO, LS~0152, LS-0237,
LS-0238 and LS-6580 treatments were applied.

Table XIII lists the results of the_weed counts in weeds per square
foot and percent control obtained when 7 herbicidal oils were applied as
basal stem treatments on 5 kinds of beans The weed counts were arranged
in 5 different groups to determine if a difference in oil susceptibility
existed between weed species. A highly significant reduction in the
number of pigweeds, ragweed, and annual grasses was found in the treated
plots. LS-0237 gave the highest percent control of pigweed and ragweed.
The percent control obtained in the grasses was the highest of any of
the weed groupings. LS-0133, LS-OlSO, and LS-OlSS gave the highest
percent control of grasses of the treatments. Highly significant re-

ductions in the number of purslane and plantian plants were found in

 

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all treated plots. LS-Ol33 and LS-OlSO gave the highest percent control
of purslane and plantian. The lamb's quarters was not reduced signifi-
cantly in the treated plots compared with the untreated but all treat-
ments were less, significantly, than treatment LS-6580. LS-OlSZ gave
the highest per cent control of lamb's quarters. Considering all weeds
the treatments gave a highly significant decrease in the number of weeds.
LS-0133 and LS-OlSO gave the highest percent control of total weeds.
Table XIV gives the yields obtained when.LS—0237 was applied at 10
gallons per acre as a basal stem spray to 5 kinds of beans at different
stages of growth under field conditions. A significant reduction in
yield occurred when 2 applications were made on the field beans and a
significant increase in yield occurred when the application was made in

the first trifoliate leaf stage of growth. Treatments at the time the

TABLE XIV

YIELDS FOLLOWING APPLICATION OF LS-0237

 

 

 

 

 

Stage of Yields in Pounds Per Acre
Growth Soybeans Fielngeans Lima Beans ‘Wax.Beans Green Beans
Unifoliate
lead 1786 11b3 3857 26h3 h7lh
lst.tri-
foliate leaf 1h29 1500* SYlh 2786 7571
3rd.tri-
foliate leaf 1857 llh3 3929 221k 5&29
Flower Bud 1857 1000 3786 1786 Slh3
Unifoliate
leaf 4-
lst.tri-
foliate leaf l7lh 857*» h21h 2071 5929
Untreated l7lh 12lh 5571 2571 6286
LSD 1% 393

LSD 5% 279

14.6

first trifoliate leaf had developed appear to have increased the yield
in the lima, wax and green beans, but the differences were not statis-
tically significant. The weeds were controlled better when the treat-
ments were applied when the first trifoliate bean leaves had developed,
Improved early weed control probably increased the yield even though
the surviving weeds were removed by hoeing early in the season. Table XV
gives the number of plants surviving the treatments at different stages
of growth in the field and lima bean plots. The number of plants was
significantly reduced in the field bean plots by all treatments except
those applied in the first trifoliate leaf stage. There were more bean
plants per row when the lima beans were treated at the first trifoliate
leaf stage but this difference did not prove significant. The double

application gave the greatest reduction in the number of plants.

TABLE XV

NUMBER OF PLANTS PER FOOT FOLLOWING APPLICATION OF LS~0237

Stage of Growth Kind of Beans

 

 

 

Field Beans Lima Beans

Unifoliate leaf 1.95% .69
lst trifoliate leaf 2.5h .6h
3rd trifoliate leaf 1.88* .61
Flower bud 1.92* .71
Unifoliate leaf +~lst

trifoliate leaf 1.62% g .50
Untreated . 2.h2 .79
LSD 1% .62

LSD 5% .hh

L7

Observations made after Spraying indicated that some of the bean
seedlings were killed when sprayed in the unifoliate leaf stage.
Observations made on August 29 indicated that some injury occurred in
all 5 kinds of beans when the treatments were applied at the third tri-
foliate leaf and flower bud stages. Lima beans were injured when the
oils were applied at the first trifoliate leaf stage. Spraying the bean
stems without injuring the leaves at the later stages of growth was very
difficult to accomplish in the field, lima, wax, and green beans.

Examination of stem cross sections showed that the double application
caused injury on all kinds of beans. No injury was found in the other
treatments in soybean, field, bean, and wax bean plots. Treatments at
all stages of growth, except the flower bud stage, caused surface injury
in lima, and green beans. Internal injury was found in sections of
green bean stems Sprayed in the unifoliate leaf stage and in lime bean
stems sprayed in the third trifoliate leaf stage.

Yields obtained from 5 kinds of beans, basal stem treated with
LS-0237 at S, 10, and 20 gallons per acre, under field conditions are
given in table XVI. There were no significant differences between yields

TABLE XVI

YIELDS FOLLOWING APPLICATION OF LS-0237

 

 

 

 

Treatment g__~ Yield in Pounds Per Acre
Gal.7Acre Soybeans Field Beans Lima Beans ‘Waszeans Green Beans
5 2071 1571 h929 521k 671k
10 2000 1357 5b29 5786 62lh
20 2000 1683 371k h6h3 6786
Untreated 2000 1357 37lh h286 6571

 

No significant difference between treatments.

 

h8

but observations made on.August 29 showed that some injury occurred at
the 20 gallon per acre plots in all beans. Severe injury was noted in
the lima bean plot when LS-0237 was applied at 20 gallons per acre and
some injury occurred in the 10 gallon per acre treatments.

Examination of stem cross sections showed surface injury in the
20 gallon per acre treatment in all beans except field beans. Injury
was also noted in lima and green bean sections treated at the 10 gallons
per acre rats.

Table XVII gives the number of grass and broad-leaved weeds per
square foot and percent control after basal stem treatment with LS-0237
at 5, 10, and 20 gallons per acre on 5 kinds of beans. Highly signifi-
cant reduction in the number of broad-leaved weeds was obtained with all
treatments but there was no significant difference between rates. The

percent control of broadbleaved weeds was highest in the 10 gallon per

acre plots. The number of grasses was significantly reduced in the

TABLE XVII

NUMBER OF WEEDS AND PERCENT CONTROL FOLLOWING APPLICATION OF LS-0237

 

 

 

 

Treatment 'Weeds Per Square Foot and Percent Control
Gallons Grass Percent Broad Leaf Percent
Per Acre . Control Control
5 .32* h? 1.76** bl
10 .l9** 66 l.16** 61
20 .21” 63 1.35H 55
Check .57 3.00
LSD 1% .28 .85

LSD 5% .20 .61

b9

5 gallon per acre treatment and highly significantly reduced in the 10
and 20 gallon per acre treatments. The percent control was greater in
the 10 gallon per acre treatment than in the 5 gallon per acre treatment.
The herbicidal oils that had given favorable results in field tests
were used in greenhouse tests to further determine the effects of the
oils upon the bean.p1ants and weeds. Table XVIII gives the dry weights
in grams per pot of stems and roots of beans grown in pots in the green-
house and basal stem treated with S herbicidal oils at 20 gallons per

acre. Neither the weight of the roots or stems gave a significant

TABLE XVIII

DRY WEIGHTS OF STEMS AND ROOTS FOLLOWING.APPLICATION
OF HERBICIDAL OILS

I

 

Dry'Weights in Grams Per Pot
Oils Used Soybeans Field Beans Lima Beans waijean Green Bean
Stem Boot Stem Root Stem Soot Stem Root Stem Root

 

 

LS-0133 h.h 2.h 3.h 3.0 7.6 2.8 3.5 1.8 3.0 1.3
LS-OlSO 3.5 1.9 2.1 2.0 5.3 2.6 2.2 .9 2.8 .7
LS-0152 5.0 2.7 3.0 3.1 5.7 1.8 2.6 1.2 3.6 1.0
LS-OlSS 3.7 2.8 3.5 3.7 b.7 2.6 2.3 1.2 2.8 .7
LS~0237 3.3 2.6 3.1 2.7 5.h 2.b 2.h .h 3.2 .6
Untreated 14.8 301 503 2.0 7.7 205 2.7 .6 2.9 o7

 

No significant difference between treatments.

 

difference between treated and untreated beans. Table XIX gives the
bean and weed injury ratings for this same experiment and the number of
nodules per pot for the green beans. Photographs of bean injury in this

test are in the appendix, figures l-h. LS-OlSS appeared to injure the

50

TABLE XIX

INJURY RATINGS FOLLOWING-APPLICATION OF HERBICIDAL OILS

 

 

Green
Injury Ratings1 Bean
Oils Used Soybean Field Bean Lima Bean wax Bean Green Bean Nodules
an Wd3 Bn Wd Bn Wd Bn Nd Bn Nd /POt

 

 

 

 

LS-Ol33 7 12 6 12 6 12 I. 12 h 10 b8
Ls-015o 8 9 8 7 7 12 3 12 5 12 39
Ls-0152 6 12 b 10 5 9 3 12 h 12 3o
Ls—0155 1. 12 2 9 2 12 1 12 2 8 20
LS-0237 2 11 7 12 8 12 9 12 5 12 21
Untreated 1 1 1 l l 1 l 1 l l 60

 

1Injury ratings: 1 = no effect, 12 - complete kill

an =- bean

3Hd - weed
field, lima, wax, and green beans less than the other oils. LS-0237
appeared to injure the soybeans least. There was little difference
between treatments in the weed injury but LS-0237 and LS-OlSZ appeared
to be slightly higher in weed toxicity. The number of nodules per pot
of green beans appeared to be less in the treated pots but the difference
was not statistically significant.

A greenhouse test was conducted to determine the effect of oil
application to beans when their stomata were Open, and again when the
stomata were closed. The soybeans that were lighted at night had stomata
that were 80 percent closed while the soybeans that were in the dark had
mostly open stomata. The bean injury ratings, number of plants surviving
and dry weights obtained when LS-0237 was applied at 20, LO, and 60

gallons per acre as a stem treatment to soybeans with open and closed

51

stomata are given in Table XX. At the 20 gallons per acre rate the
injury ratings indicated more injury occurred when the stomata were open
during spraying and this proved significant. Fewer of the plants sur-
vived when they were Sprayed with their stomata open. The dry weight

per pot appeared to be less when the plants were sprayed with the stomata

open but this was not statistically significant.

TABLE XX

BEAN INJURY RATINGS, NUMBER OF PLANTS SURVIVING
FOLLOWING APPLICATION OF LS—0237

 

 

 

Amount Bean1 Number of Dry Weight
of Oil Injury Plants Grams
Used Rating, Surviving__ Per Pot
Stomata Stomata Stomata
Gals.[Acre .Qpen Closed Open Closed Open Closed
20 8.0% h.5* 3.5 5.8 2.0 3.2
140 9.5 8.0 2.5 2.8
60 10.5 10.5 2.2 lq2
Untreated 1 1 6.0 6.0 h.0 3.6

IInjury ratings: 1 = no effect, 12 - complete kill.

Table XXI gives the number of weeds and percent control after
treatment of 3 weeks old weeds in greenhouse flats with LS-0237 at S,
10, and 20 gallons per acre. At the 5 gallon per acre rate, lamb's
quarters, legumes, smartweed, and mouse-ear chickweed were the only
weeds on which less than 90% control was obtained. At the 10 gallon per
acre rate, lamb's quarters was the only weed not controlled to the
extent of 90% or better. All weeds were killed at the 20 gallon per

acre rate. ‘When all weeds are considered, S, 10, and 20 gallon per acre

52

TABLE XXI

NUMBER OF WEEDS AND PERCENT CONTROL FOLLOWING APPLICATION OF LS-0237

 

 

Gallons of Oil For Acre

 

 

 

 

 

Kind of Untreated Si 10 20
Weedl- Number No. con- No. %’c0n- No. %’con-
' trol trol trol

Grass 13.19 1.18 91 .29 98 0.00 100
Lambs-quarter 15.15 b.71 69 1.62 89 0.00 100
Legume 3.2a 1.32 61 0.00 100 0.00 100
Oxalis 1.h7 0.15 90 0.00 100 0.00 100
Smart Heed 2.06 0.hh 79 0.15 93 0.00 100
Mouse-ear

Chickweed .7h 0.15 80 0.00 100 0.00 100
Bull Thistle .hh 0.00 100 0.00 100 0.00 100
Total 36.18 7.95 78% 2.06 9h% 0.00 100%

Grass (Poa_pratensia L.)
(Digitaria sanguinalis (L. ) Scop.)
(Dactylnglomerata L .)
(Setaria spp. )
Lamb's quarters (Chenoppdium album L.)
Legume (Melilotus, Medicaco and Trifolium spp.)
Oxalis (Oxalis stricta L.)
Smart Weed (Polygonum Persicaria L J
Mouse-ear chickweed (Cerastium vulgatum L.)
Bull thistle (Cirsium lanceolatum (L. TiHiIl)

1Kind of weed:

 

 

 

 

 

 

of LS-0237 gave 78, 9b, and 100 percent control, respectively. Photo-

graphs of the treated flats are in the appendix, figure 16.
Table XXII gives the number of weeds per square foot and percent

control obtained when S herbicidal oils were applied at 10 gallons per

acre to 3 week-old weeds grown in flats in the greenhouse. The oils did

not give a high percent of control of large crabgrass but this was prob;

ably due to additional germination after treatment. LS—0237 gave the

53

 

 

 

 

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ea o.m ma H.m Hm ~.m a» m.e we m.4 o.ma woos peaem
o o.m o N.@ ma ©.m o m.m ma m.m 4.: coosmom
mm m.e 6a H.~H we o.m Ha a.HH ea a.oa 6.6; oooamaa
ca c.H we c.sH Ha m.m mm 4.: ea a.~ m.am acaemoa
4a m.H Ho m.mH cm a.m ea m.a aw m.m m.Hm acsaeaeooasg
66 c. 06 m. om a. om a. o: a. m.H .Haoexoa
em o.o~ am m.aw om a.aH mm c.aw mm o.aa 6.0m easawosao amass
ow a.m we 4.6H 6a m.: mo m.c we H.m. H.mH cacao seam
Axospaox

Hop» moooS Hohp moomz Home memos. Hone 66663. Hon» moooz oomo3
Icoo m mo.oz Ico07M. Ho.oz taco m Ho.oz 1:601M1,Mo.oz 1:00 m mo.oz mo .02 memo:
amNoumo mmaoumg mmaosmg omaonmg mmao-mg cosooaeap mo case

 

 

mAHo AdaHonmmm m6 ZOHH40HAmmd_mZH3OAAOw Homezoo azmummm Qz<.mnmm3 mu mmnzbz

HHxN mAde

5b.

highest percent control of Kentucky bluegrass, lamb's quarters, legumes
and oxalis. LS-OISS gave the best control of foxtail and curled dock.
LS-0152 gave the best control of pigweed, smart weed and shepherd's
purse. Ragweed appeared to be very resistant to oil treatments. LS-OlSZ
and LS-0237 gave the best total weed control. LS-OlSO and LS—OlSS gave

the poorest total weed control.

55

DISCUSSION

The use of oils as herbicides dates back to the early 1900's.
Research workers found that certain oil fractions were phyto-toxic and
oils were developed for selective weed control. Later, oils were used
as directed sprays on onions, cotton, and soybeans.

Typical oil injury observed on the bean plants when a toxic oil was
applied to the lower 1 inch of the stem was a wilting of the plant
similar to that in a plant suffering from a lack of water. The leaves
and stems were limp and the treated area appeared watersoaked. Apparently,
the oil destroyed the semi-permeability of the cell membranes and inter-
rupted the water transfer to the leaves. If the entire plant was not
killed, the treated area was severely burned and turned a dark brown.'

Two toxic oils caused a weakening of bean stems in field tests. Exami-
nation of cross sections of beans stems treated in the field indicated
that injury to the epidermis and cortex or an internal injury occurred.
The surface injury was characterized by a breakdown of some cells in the
epidermis and cortex and a reversion of the adjacent cells to meristematic
activity with a formation of a periderm layer. The internal injury was
characterized by a breakdown of cells in the cortex, phloem and vascular
cambium with adjacent cells reverting to meristematic activity and form-
ing a periderm layer. The internal injury was of the same type as the

surface injury but was a result of deeper penetration into the stem.

56

The injury to the vascular cambium could cause an interruption in water
movement within the plant.

Field tests conducted in 1953 and l9Sh with basal stem directed oil
applications gave no significant reduction in yield in the 5 kinds of
beans tested. LS—0133 (90% mineral spirits, 10% Indocene 70), LS—OlSO
(90% mineral spirits, 10% Indosolvent 2), LS—0152 (85% mineral spirits,
15% Indocene 70), 1.5—0155 (1.0% mineral spirits, 1.0% alkylate, 20% Indosol-
vent 2) and LS-0237 (Heavy Naptha) gave good weed control with I treat-
ment at 10 gallons per acre as 6 inch band treatments in 22 inch rows
and gave little injury to the beans. LS-0152 and LS~O237 gave the best
weed control but with slightly more injury to the beans. Grasses were
controlled better than other weeds by oil treatments. Ragweed (Ambrosia

artemisiifolia L.) was resistant to herbicidal oils. Lamb's quarters

 

(Chengppdium album L.) was somewhat resistant to herbicidal oils and

 

some tests indicated that if the oil Spray did not reach the terminal
growing points, the plants were not killed.

Experiments in the field and greenhouse, on the amount of oil to
apply, indicated that additional bean injury occurred when 20 gallons
per acre of the oil was applied compared with the S and 10 gallon per
acre rates; however, no significant yield reduction was found. In the
greenhouse tests, 5 and 10 gallon applications of LS-0237 gave 78 and 90
percent control, respectively, of all weeds. In field tests, 5 gallons
per acre applications of LS-0237 gave h? percent grass control and hl
percent broad-leaved weed control while 10 gallons per acre appli-

cations gave 66 percent grass control and 61 percent broad-leaved weed

57

control. Twenty gallon per acre applications of LS-O237 gave no better
weed control than the 10 gallon per acre rate. The rate of application
tests indicated that if weeds were small, a low volume gave excellent
control but larger weeds required a greater volume of Spray to obtain
satisfactory control.

Stage of growth experiments in the greenhouse and field indicated
that susceptibility to oil injury increases with the age of the plant.
No significant reduction in yield occurred when the beans were Sprayed
at different stages of growth. Before the plant had developed its first
trifoliate leaves it was difficult, mechanically, to apply oil to the
stems without causing leaf injury. After the field, lima, wax and green
beans had deve10ped their third trifoliate leaf, placement of the oil
under the leaves was very difficult. The best weed control was obtained
when the beans were Sprayed in the first trifoliate leaf stage.

Repeated applications of LS-0237 did not cause a Significant re-
duction in yield but more bean injury occurred than with single appli-
cations. Repeated applications did not cause significantly weaker bean
stems in greenhouse tests.

Applications of LS-0237 in 60, 70 and 800 F. temperatures indicated
that least injury occurred with the 600 F. application when 20 gallons
per acre were applied as basal stem treatments in the greenhouse. Tests
with LS-0237 applied as basal stem treatments to soybeans with stomata

Open and closed indicated that more injury occurred when stomata were

Open a

58

The beans were rated in order of decreasing oil resistance as
follows: field beans, soybeans, waxbeans, green beans, and lima beans.
Heavy Naphtha (Boiling range 3O2-39SOF., 19% aromatics) and a
mixture of 85% mineral spirits and 15% Indocene 70 show'promise for use
on beans as a basal stem spray for post-emergence weed control. Oils
can be applied to stems of beans without injury to the leaveS'with a
sprayer that has nozzles directed horizontally toward the base of the
bean stem with a floating shield protecting the upper portion of the

plant.

For the best weed control, and to facilitate application, oil sprays
should be applied when the plant has the first trifoliate leaf. An ad-
ditional application can be made a week or more later but applications
Without leaf injury may be difficult with field, lima, wax and green
beans. Applications made in temperatures of 60° F. give less bean
injury. Ten gallons per acre applied in 6 inch bands on rows 22 inches
apart will give 70-80 percent control of weeds. Grasses are controlled
better than broad-leaved weeds Ragweed is not controlled by oil Sprays
and lamb's quarters has to be Sprayed when less than 1 1/2 inches high
to be effectively controlled.

Some burning of the bean stems occurs with oil application but there
is no reduction in yield. Lima beans are injured more than other beans

from oil Sprays.

59

SUMMARY

1. Soybeans (Glycine max, variety Hawkeye), field beans (Phaseolus

 

vulgaris, variety Michelite), lima beans (Phaseolus lunatus, variety

 

Fordhook Dwarf), wax beans (Phaseolus vulgaris, variety Pencil Pod Wax),

 

and green beans (Phaseolus vulgaris, variety Tendergreen.Bush) were basal

 

stem treated with herbicidal oils and the effect of the oil upon the
beans and weeds was determined.

2. The herbicidal oils were applied manually in the greenhouse with
a small DeVilbis Sprayer and in the field with a power driven Sprayer
that was designed to apply the oil at the base of the bean stems.

3. The effects of the herbicidal oils were determined by yields of
beans, dry weight of the bean plants in the greenhouse, injury ratings,
microscoPic examination, and weed counts.

h. Thirty-two experimental oils were screen tested for weed control
and injury to the beans.

5. The following experimental oils gave good weed control with
little injury to the bean plants when applied with the power driven di-
rected Spray Sprayer.

a. LS—0133 (90% mineral spirits, 10% Indocene 70)
b. LS—OlSO (90% mineral Spirits, 10% Indosolvent 2)
c. LS-0152 (85% mineral spirits, 15% Indocene 70)
d. LS-0155 (50% mineral spirits, h0% alkylate,
20% Indosolvent 2)
e. LS-0237 (Heavy naphtha)
6. No significant reduction in yield occurred when the herbicidal

(oils were applied at 10 gallons per acre in a 6 inch band treatment

60

on rows 22 inches apart. Approximately 75% of the weeds were con-
trolled.

7. Examinations of cross sections of the bean stems treated in the
field indicated that oil injury may occur to the epidermis, cortex,
phloem, and vascular cambium cells.

8. Oil injury from a toxic oil was observed as a wilting of the
plant similar to that of a plant suffering from the lack of water.

The treated stem area appeared watersoaked and later turned brown.

9. Grasses were controlled more readily than broad-leaved weeds
with oil treatments. Ragweed (Ambrosis artemisiifoli§_L.) was resistant
to oil and lamb's quarters (Chenopodium album L.) required complete
coverage of the terminal growing point for control.

10. Twenty gallons per acre of LS-O237 caused some additional bean
injury and gave no better weed control than 10 gallons per acre while
5 gallons per acre gave less weed control.

11. A repeat application of LS—0237 caused some additional injury
but the yield was not reduced significantly.

12. Tolerance for oil Spray in beans was greatest at the unifoliate
leaf stage. Localized injury occurred on older beans but no reduction
in yield was observed.

13. The first trifoliate leaf stage was best from the standpoint of
mechanical application of oil and gave the best weed control.

1h. Twenty gallons per acre of LS~0237 applied at 600 F. gave less

bean injury than when applied at 700 and 80° F.

61

15. Twenty gallons per acre of LS-0237 applied to soybean stems
gave Significantly less injury when applied to stems with closed stomata.
16. The beans in order of decreasing oil tolerance are: field

beans, soybeans, wax beans, green beans, and lima beans.

1.

2.

6.

7.

8.

10.
ll.
12.

13.

62

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Yowell, H. L., Progress in the Herbicidal Application of Oil,
Proc. Fourth Ann. Meet. Northeast.‘weed Control Conf., h3-50, 1950.

APPENDIX

EXPERIMENTAL HERBICIDAL OILS AND DATA ON

THEIR COMPONENTS.AND PROPERTIES

69

 

 

 

 

Boiling Aniline
Code Range Point Percent
Numbers Composition Degree Degree Aromatic Olefin Naph- Paraf-
F . C . thene fin
LS- 0132 85% Mineral spir- 23.h
its, 15% Indo-
solvent 2
LS-0133 90% Mineral Spir- 18.5
its, 10% Indocene
7O
LS-01h7 El Dorado 223-h0h 16.5 trace 18.5 65
Heavy Naphtha
Ls-0150 90% Mineral Spir- 18.9
its, 10% Indo-
solvent 2
LS-0151 80% Mineral Spir- 27.8
its, 20% Indo-
solvent 2
LS-0152 85% Mineral Spir- 22.7
its, 15% Indocene
70
LS-0153 80% Mineral Spir- 27.0
its, 20% Indocene
7O
LS-015h b0% Mineral Spir- 23.8
its, not Alkylate,
20% Indosolvent 2
LS-0155 h0% Mineral Spir- 23.0
its, h0% Alkylate
20% Indocene 7O
LS-Ol78 50% Mineral Spir- 5.0
its, 50% Alkylate
LS-0235 Octane 100
LS-0237 Heavy Naphtha 302-395 19.0 trace 19.5 61.5
LS-0238 306-38h 21.5 trace h1.S 37.0

7O

 

 

 

 

(Continued)
Boiling Aniline
Code Range Point Percent
Numbers Composition Degree Degree Aromatic Olefin Naph- Paraf-
F. C. thene fin
L-3388 Stoddard Solvent 316-390
L-6h19 Indocene 9O b00-h75 16 79.2
L-6580 VM&P Naphtha 205-325 55.8 lh.O
L-6581 High-flash 295-372 56.1 13.0
VMlP Naphtha
L-6639 Amyl benzene 316-390 100.0
L-66h0 N-Decane 316-390 100
L-68h0 25% Amyl benzene 25.0
75% No. 10 base
oil
L-68L1 25% mono amyl- 35.5
benzene, 75%
Regular oleum
spirits
L-7297 25% Indocene 70 32.0
75% Stoddard
Solvent
L-7565 Mineral Spirits 316-h06 59.1: 10.0
L-77lO Indocene 701 290-th 17.1 100.0
2
L-7718 Indosolvent 2 270-310 1b.? 100.0
L-793h Emulsifiable 97 .0
Indocene 7O
L-8712 Dodecane 100
L-89h9 10% trimethyl- 9.1;
benzene, 90%
tetradecane
L-8950 15% trimethyl- 111.1

benzene, 85%
tetradecane

71

 

 

 

 

(Continued)
Boiling .Aniline
Code Range Point Percent
Numbers Composition Degree Degree Aromatic Olefin Naph- Paraf-
F. C. thene fin
L-8951 10% tetramethyl-
benzene, 90%
tetradecane
L-8952 15% tetramethyl-
benzene, 85%
tetradecane
L-2988 No. 10 base oil 350-h87 73.h 0.0
L-2h6 Regular oleum 3lO-h25 59.7 12.5
Spirits

 

1Indocene 70 h% toluene
32% meta, para, and ortho xylene
21.5% 1,3,5, trimethylbenzenes
2h.5% 1,2,h trimethylbenzenes
6.5% 1,2,3 trimethylbenzenes
11.5% other aromatics

2Indosolvent 2 6h% ortho, meta, and para xylenes
23% ethylbenzene
1.1% Ca paraffins
9% Primarily aromatics

Figure 1

Figure 2

Figure 3

Figure h

Pot on left: Green bean plants, basal stem treated
with LS-0237 in the greenhouse, showing
typical oil injury 2 months after
treatment.

Pot on right: Untreated green bean plants.
Pot on left: wax bean plants, basal stem treated with

LS-0237 in the greenhouse, showing typical
oil injury 2 months after treatment.

Pot on right: Untreated wax bean plants.

Pot on left: Lima bean plants, basal stem treated with
LS-O237 in the greenhouse, showing typical
oil injury 2 months after treatment.

Pot on right: Untreated lima bean plants.

The three soybean plants on the left were treated.with

LS-0237 in the greenhouse and show typical oil injury
2 months after treatment. Plant on right is untreated.

 

Figure

Figure

Figure

Figure

Cross section of a stem of an untreated soybean
plant (I hOO)

Cross section of a stem of a soybean plant, basal stem
treated with L-7710 in the field, showing typical
surface oil injury. (I hOO)

Cross section of a stem of an untreated lime bean
plant. (X hOC)

Cross section of a stem of a lima bean plant, basal
stem treated with LS-O237 in the field, showing
typical surface oil injury. (1 L00)

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Figure 9

Figure 10

Figure 11

Figure 12

Cross section of a stem of an untreated wax bean
plant . (x boo)

Cross section of a stem of a wax bean plant, basal stem
treated with L-7710 in the field, showing typical
surface oil injury. (I hOO)

Cross section of a stem of an untreated green bean plant.
(I hOO)

Cross section of a stem of a green bean plant, basal stem
treated with L-7297 in the field, showing internal oil
injury, (x boo)

 

77

VIII!"

 

 

 

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Figure 20 Apparatus to measure strength.and resilience
of bean stems.

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43 2861

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