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The Interaction of Acetolactate Synthase Inhibiting
Herbicides with Graminicides and Insecticides

presented by

Antonio Castro-Escobar

has been accepted towards fulfillment
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THE INTERACTION OF ACETOLACTATE SYNTHASE INHIBITING
HERBICIDES WITH GRAMINICIDES AND INSECTICIDES

By

Antonio Castro-Escobar

A THESIS

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

MASTER OF SCIENCE

Department of Crop and Soil Sciences

1995

ABSTRACT

THE INTERACTION OF ACETOLACTATE SYNTHASE INHIBITING
HERBICIDES WITH GRAMINICIDES AND INSECTICIDES

BY

ANTONIO CASTRO-ESCOBAR

The acetolactate synthase inhibitors may interact antagonistically with acetyl-
CoA carboxylase inhibitors to reduce grass control. ALS inhibitors may also interact
synergistically with soil applied insecticides such as terbufos and may injure corn.
Greenhouse studies were conducted to evaluate the antagonistic interaction between
imazethapyr, technical and formulated, with graminicides in giant foxtail control. The
effect of ammonium sulfate in the interaction was also evaluated. 2-Ketobutyrate may
accumulate as a result of the blocking of the ALS enzyme by ALS inhibitors. Thus,
the role of excess 2-ketobutyrate on the interaction of imazethapyr and fluazyfop-butyl
was also studied in giant foxtail. In addition, field studies were conducted to evaluate
the interaction of the ALS inhibitors nicosulfuron and primisulfuron with the insecticide
terbufos. A rapid pesticide detection kit was evaluated for terbufos detection in com
shoot extract.

An antagonistic interaction resulting from the formulated imazethapyr and the
imazethapyr technical product with the graminicides, fluazifop-butyl, sethoxydim,

quizalofop, and UBI-C4874 was observed on giant foxtail control. No antagonistic

interaction was observed with the formulation blank and the graminicides suggesting
that a chemical antagonism was unlikely. The addition of ammonium sulfate to the
tank mixture overcame the antagonistic interaction.

The inclusion of 2-ketobutyrate caused a reduction in giant foxtail shoot fresh
weight. A significant antagonistic interaction was observed between fluazifop-butyl

and 2-ketobutyrate applied at 10'2

M . The metabolic intermediates 2-ketobutyrate, 2-
aminobutyrate, or pyruvate combined with imazethapyr increased injury to giant
foxtail. Addition of 2—ketobutyrate appeared to overcome the antagonistic interaction
between imazethapyr and fiuazifop-butyl.

Postemergence applications of nicosulfuron and primisulfuron to corn grown in
a field previously treated with terbufos for corn rootworm control resulted in a
synergistic interaction injurious to com. A strong correlation between corn injury and
the amount of terbufos level detected with the pesticide detector kit in the shoot extract
was obtained. The pesticide detector kit was an efficient method to detect the presence
of terbufos in the corn plants. Nomenclature: Imazethapyr, 2-[4,5-dihydro~4-methyl-
4-(l-methylethyl)-5-oxo-1H-imidazol-Z-yl]-S-ethyl-3-pyridinecarboxylic acid;
fiuazifop, 0-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]-oxy]phenoxy]propanoic acid;
sethoxydim , 2-[ l -(ethoxymino)butyl]-5-[2-(ethilthio)propyl]-3-hydroxy-2-cyclohexen-1-
one; quizalofop, ()-2[4—[CG-chloro-2-quinoxalinyl)oxy]phenoxy]propanoic acid; UBI-
C4874, O-tetrahydrofuryl(R)-2-[4-(-6chloroquinoxalin-Z-yloxy)phenoxy]propanoic
acid; nicosulfuron, 2[[[[(4,6-dimethoxy-Z-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-
N,N-dimethyl-3-pyridinecarboxamide; primisulfuron, 2-[3-[4,6-bis(difluoromethoxy)-

pyrimidin—Z-yl]-ureidosulfonyl]-benzoic acid methylester; terbufos, S—[[(l ,1-

dimethylethyl)thio]methyl]0,0—diethylphodphorodithionate; corn, [Zea mays L.]; giant

foxtail, [Setariafaberi Herrm.].

Copyright by
ANTONIO CASTRO-ESCOBAR

1995

ACKNOWLEDGMENTS

I would like to express sincere gratitude to my major professor, Dr. Donald
Penner, for his patience, guidance, and scientific expertise throughout the entire
project. I would also like to express appreciation to my committee members, Dr. Jim
Kells and Dr. Bernard H. Zandstra, for their help in reviewing this manuscript.

Special thanks is expressed to Frank C. Roggenbuck for his valuable technical
assistance from the beginning of the research through the completion of this thesis.

Finally, I extend appreciation to my wife, Julie Anne, for her support through
the completion of my study.

To my parents, Juan Castro and Nicolasa Escobar, for their love and support

through my career.

vi

TABLE OF CONTENTS

PAGE

LIST OF TABLES .................................... ix

LIST OF FIGURES .................................... x

INTRODUCTION ..................................... 1
CHAPTER 1. OVERCOMING THE ANTAGONISTIC INTERACTION

OF IMAZETHAPYR WITH GRAMINICIDES ........ 2

Abstract ................................. 2

Introduction .............................. 3

Materials and Methods ........................ 4

Results and Discussion ........................ 5

Literature Cited ............................ 15

CHAPTER 2. MODULATORS OF IMAZETHAPYR ACTIVITY
AND THE INTERACTION OF IMAZETHAPYR

AND FLUAZIFOP-BUTYL .................... 16
Abstract ................................. 16
Introduction .............................. 17
Materials and Methods ........................ 18
Results and Discussion ........................ 21
Literature Cited ............................ 27

CHAPTER 3. USE OF ORGANOPHOSPHATE INSECTICIDE
LEVELS IN CORN SEEDLINGS AS AN INDICATOR
OF INJURY POTENTIAL FROM POSTEMERGENCE
APPLICATIONS OF SULFONYLUREA HERBICIDES . . 30

Abstract ................................. 30
Introduction .............................. 31
Material and Methods ........................ 32
Results and Discussion ........................ 34
Literature Cited ............................ 43
SUMMARY ....................................... 46

vii

APPENDIX ....................................... 48

viii

LIST OF TABLES

TABLE PAGE
Chapter 1
l. The interaction of imazethapyr on the effect of various

graminicides on the visual injury and shoot growth of

giant foxtail 14 days after postemergence herbicide application ....... 7
2. The effect of imazethapyr formulations on the interaction of I

mazethapyr and several and several graminicides ................. 8
3. The effect of ammonium sulfate on the interaction of imazethapyr

and several graminicides ................................ 10
Chapter 2
l. The effect of 2-ketobutyrate and its role on fluazifop-butyl activity

in nutrient culture study ................................ 23
2. The effect of 2-ketobutyrate on the interaction of fluazifop—butyl

plus imazethapyr ..................................... 24
3. The effect of AA precursors on imazethapyr action .............. 25
4. The effect of 2-ketobutyrate on imazethapyr activity on soybean ...... 26
Chapter 3
I. The effect of terbufos interaction with acetolactate synthase inhibiting

herbicides on corn ................................... 36

ix

LIST OF FIGURES

FIGURE PAGE
Chapter 1.
1. Role of ALS in synthesis of branched chain amino acids and

pantothenate ....................................... 12
2. Role of ACCase in the metabolism pathway of pantothenate

to malonyl CoA ..................................... 14
Chapter 2.
1. Standard curve for Enzytec Pesticide Detector Kit ............... 38
2. Correlation of corn injury from postemergence application of two

rates of nicosulfuron to various levels of terbufos applied as

in-furrow soil application. Enzytec Pesticide Detector Ticket Kits

were used for the detection of terbufos present in corn tissue at time

of herbicide application ................................ 40

3. Correlation of corn height from postemergence application of two
rates of nicosulfuron and primisulfuron to various levels of terbufos
applied as in-furrow soil application. Enzytec Detector Ticket Kits
were used for the detection of terbufos present in corn tissue at time
of herbicide application ................................ 42

INTRODUCTION

Herbicides have been the most frequently used chemicals in modern crop management
systems. Today, the use of more than one chemical in the same crop is a common production
practice.

Herbicides might be applied as a mixture with adjuvants, fertilizers, fungicides,
insecticides, nematicides, or other herbicides. The increase in no-till and minimum tillage
acreage, improved biological performance, environmental and economic incentives, and weed
resistance management are some of the factors that have sparked the use of chemical
mixtures.

Undesired interactions among pesticides can occur. The interaction between ALS
inhibitors with graminicides and insecticides has become the focus of considerable research.
The interaction of ALS inhibitors with graminicides may result in loss of weed control; the
interaction of ALS inhibitors with insecticides may result in crop injury.

The objectives of these research were: 1) to determine the extent and basis of the
imazethapyr and graminicide interaction, 2) to determine whether the imazethapyr
formulation contributes to the interaction, 3) to determine whether tank-mixing ammonium
sulfate with imazethapyr and a graminicide will overcome the observed interaction, 4) to
determine whether 2-ketobutyrate was involved in the observed interaction, and 5) to evaluate
a quick and easy to use kit to detect the presence of terbufos in corn seedlings at levels that

result in corn injury from postemergence applications of nicosulfuron and primisulfuron.

CHAPTER ONE
OVERCOMING THE ANTAGONISTIC INTERACTION
OF IMAZETHAPYR AND GRAMINICIDES

Abstract. The effect of imazethapyr formulations on the activity of several graminicides was
studied under greenhouse conditions. The effect of imazethapyr formulation and ammonium
sulfate on the interaction of imazethapyr and graminicides was also evaluated. Formulated
imazethapyr, imazethapyr formulation blank, and imazethapyr technical product were applied
in a tank-mixture with various graminicides at one-fourth and one-half of the normal
application rate to giant foxtail. An antagonistic interaction of the formulated imazethapyr
and the imazethapyr technical product with the graminicides, fluazifop-butyl, sethoxydim,
quizalofop-ethyl, and UBI-C4874 on giant foxtail control was observed. Since this
antagonistic interaction was not observed with the formulation blank and the graminicides, a
chemical interaction is unlikely. The addition of 1. 12 kg/ha of ammonium sulfate to the
spray mixtures overcame the observed antagonistic interaction. The explanation for the
observed effect of ammonium sulfate appeared to be the enhancement of imazethapyr activity
on giant foxtail control. Nomenclature: Fluazifop, (i)-2-[4-[[5-(trifluoromethyl)-2-
pyridinyll-onyphenoxy] propanoic acid; imazethapyr, 2-[4,5-dihydro-4-methyl-4-(l-
methylethyl)-5-oxo-lH-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid; quizalofop, (:t)-2[4-
[CG-chloro—2-quinoxalinyl)oxy] phenoxy]propanoic acid; sethoxydim, 2-[1-
(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-l-one; UBI-C4874, (i)-
tetrahydrofurfuryl(R)-2-[4-(6-chloroquinoxalin-2-yloxy)phenoxy]propanoic acid; giant foxtail,

Setariafaben’ Herrm. # SETFA.

3
Additional index words: Ammonium sulfate, imazethapyr, quizalofop, sethoxydim,

UBI-C4874, SETFA.

INTRODUCTION

The use of two or more agrochemicals on the same crop has become a common
production practice (3). Sequential applications of agrochemical mixtures or combinations
such as mixtures of herbicides with adjuvants, fertilizers, fungicides, insecticides,
nematicides, or other herbicides may be used as part of modern pest management practices.

The growing number of herbicides that are off patent, the increased demand for
greater weed control, and the increase in no-till and minimum tillage acreage are some of the
contributing factors for the use of more herbicide mixtures. However, a broader spectrum of
weed control and decreased costs of application are the primary reasons for using herbicide
mixtures (3). Other economic and environmental incentives have also increased the
importance of herbicide mixtures. The use of mixtures decreases the number of trips across
the field, saves fuel, decreases labor, and reduces the mechanical damage to the crop and
soil. Herbicide combinations may also prevent the development of resistant weed species
which result from the long-term use of a single effective herbicide.

Despite the biological and economic advantages, problems are also associated with
herbicide mixtures. An example of these problems is the interaction of imazethapyr with
various graminicides.

Soybean growers have found imazethapyr an effective postemergence herbicide;
however, grass control may not be as good as desired. Tank-mixing graminicides effective
for grass control in soybeans with imazethapyr has been reported to cause antagonism in the
control of grasses (4). The extent and basis or the role of the imazethapyr formulation in this
interaction have not been determined. Sequential applications of the graminicide and
imazethapyr prevent the interaction but is more costly and demanding of time than the

application of tank-mixture. The addition of ammonium sulfate to bentazon effectively

4
overcame the antagonistic interaction between bentazon and sethoxydim (8). The potential
for ammonium sulfate to facilitate tank-mixing graminicides with imazethapyr merits
investigation. It would be beneficial if a system could be found to mix imazethapyr with
grass herbicides without reducing the performance of such herbicides.

The objectives of this research were: a) to determine the extent and basis of the
imazethapyr and graminicide interaction, b) to determine whether the imazethapyr
formulation contributes to the interaction, and c) to determine whether tank-mixing
ammonium sulfate with imazethapyr and a graminicide will overcome the observed

interaction.

MATERIALS AND METHODS
Imazethapyr and graminicide interaction studies. Giant foxtail was grown in 945-ml
plastic pots containing Baccto potting media. The pots were placed in the greenhouse at
25 12°C with 16-h days. Natural plus supplemental lighting with high pressure sodium
lighting provided an average of 1200 th'mzs'1 in the greenhouse. After emergence, plants
were thinned to three plants per pot. Herbicide treatments were applied postemergence to the
grass plants at the three- to four-leaf stage. The herbicide treatments included 12.9 and 25.0
g ai/ha of imazethapyr formulated product, formulation blank, and 4.25 and 8.5 g/ha of
technical product, respectively. Graminicides used were fluazifop—butyl (53.4 and 106.8 g
ai/ha), sethoxydim (53.9 and 107.8 g ai/ha), UBI-C 4874 (24.9 and 49.9 g ai/ha) and
quizalofop-ethyl (24.9 and 49.9 g ai/ha), respectively. Each of the graminicides and
imazethapyr formulation experiments were conducted separately. For that reason, a separate

LDS value is presented for each study. All herbicide treatments were applied with 1% v/v of

crop oil concentrate except quizalofop-ethyl which was applied with 1/4% of the non-ionic

5
surfactant X-771. Ammonium sulfate at rate of 1.12 kg/ha was also applied as tank mixture
with the herbicides.

Herbicide treatments were applied with a continuous link belt sprayer at 193 kPa
pressure and 230 L/ha volume. A completely randomized design was used and each
treatment was replicated four times. Data presented are the means of two experiments.

Visual injury 14 days after herbicide treatment and shoot height 16 days after
treatment were used as a measure of grass control. Visual injury rating scale of 0 to 100%
was used with complete death of grass plants receiving a rating of 100%. Following the
factorial analysis of variance, means were separated with Fisher's protected LSD at the 5%

level of significance.

RESULTS AND DISCUSSION

An antagonistic interaction of the imidazolinone, imazethapyr, and the graminicides,
fluazifop—butyl, sethoxydim, quizalofop-ethyl, and UBI-C4874 on annual grass control was
observed in the greenhouse study (Table l). Myers and Coble (4) have previously reported
observing the antagonistic interaction with tank-mixtures of imazethapyr with fiuazifop-butyl,
sethoxydim, and quizalofop-ethyl. They were able to overcome the interaction with
sequential applications of graminicides and imazethapyr. The antagonistic interaction of Na-
bentazon with sethoxydim was similarly overcome with sequential applications (2, 5).
Wanamarta et a1. (7) identified this interaction as a chemical interaction in which the Na+
from the formulated bentazon associated with the sethoxydim to form Na-sethoxydim.
Imazethapyr is commercially formulated as the NH4+ salt. Since fluazifop-butyl and

quizalofop-ethyl are esters, they are unlikely to compete with imazethapyr for the NH4+

 

1X-77 nonionic surfactant is a mixture of alkylarylpolyoxyethylene glycols, free fatty
acids, and isopropanol marketed by Valent U.S.A. Corp, 1333 N. California Blvd., Walnut

Creek, CA 94596.

6
leaving imazethapyr vulnerable to the formation of CA+ + and Mg+ + salts. These salts are
less readily absorbed by plants resulting in a reduced weed control.

Gerwick, et a1. (1) could not explain the imidazolinone herbicide interaction with the
graminicide on the basis of decreased absorption of the graminicide. They suggested that the
antagonism resulted from a physiological link between the effect of the imidazolinone on
acetolactate synthase and the graminicide effect on acetyl-CoA carboxylase. The results
presented in Table 2 indicate that the antagonistic interaction occurred with the technical as
well as the formulated imazethapyr. The formulation blank did not affect graminicide
activity. Thus, a chemical interaction between the imazethapyr formulation and the
graminicide is unlikely.

The addition of ammonium sulfate to the spray solution helped overcome the
antagonistic interaction on annual grass control (Table 3). The explanation for the observed
effect of ammonium sulfate appears to be the enhancement of imazethapyr activity on grass
control. Fluazifop-butyl activity was not enhanced by the ammonium sulfate. This was
expected since the fluazifop-butyl is an ester and not a salt. The presence of Ca++ and
Mg+ + in hard water may overwhelm the NH4+ from the NH4+ imazethapyr and result in

+ + and Mg+ + salts of imazethapyr. The Ca++ and Mg++ salts of

the formation of Ca
herbicides are usually not absorbed as well as the NH4 salts (6, 7).

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15

LITERATURE CITED
Gerwick, B.C., P.C. Thompson, and R. Noveroske. 1988. Potential mechanism in
antagonism with arloxyphenoxypropionate herbicices. Abstr. Weed Sci. Soc. Amer.
28:284.
I-Iartzler, R.G., and CL. Foy. 1983. Compatability of BAS 90520H with
acifluorfen and bentazon. Weed Sci. 31:597-599.
Hatzios, K. K. and D. Penner. 1985. Interactions of herbicides with other
agrochemicals in higher plants. Rev. Weed Sci. 1:1-63.
Myers, F. and D. Coble. 1992. Antagonism of graminicide activity on annual grass
species by imazethapyr. Weed Technol. 6:333—338.
Rhodes, G.N., Jr., and H.D. Coble. 1984. Influence of bentazon on absorption and
translocation of sethoxydim in goosegrass (Eleusine indica L.). Weed Sci.
32:555-597.
Thelen, K.D., E.P. Jackson, and D. Penner. 1992. Use of proton magnetic
resonance spectrometry for determining chemical-based herbicide antagonism. Proc.
North Central Weed Sci. Soc. 47: 108.
Wanamarta, G., D. Penner, and J. J. Kells. 1989. The basis of bentazon
antagonism on sethoxydim absorption and activity. Weed Sci. 37:400—404.
Wanamarta, G., D. Penner, and J. J. Kells. 1993. Overcoming antagonistic effects

of Na-bentazon on sethoxydim absorption. Weed Technol. 7:322-325.

CHAPTER TWO
MODULATORS OF IMAZETHAPYR ACTIVITY AND THE INTERACTION OF
IMAZETHAPYR AND F LUAZIF OP-BUTYL

Abstract. The herbicides that inhibit acetolactate synthase and herbicides that inhibit acetyl-
CoA carboxylase interact antagonistically to reduce grass control. The role of excess 2-
ketobutyrate on the interaction of imazethypyr and fluazifop-butyl was studied in giant foxtail.
In sand cultivar studies in the greenhouse, the inclusion of 10'4 M 2-ketobutyrate in the
nutrient solution caused a 44% reduction in giant foxtail shoot fresh weight. A significant
antagonistic interaction was observed following foliar application of 53.4 g/ha fluazifop-butyl
to plants provided with 10'4 M 2-ketobutyrate. Foliar application of 10'3 M 2-ketobutyrate,
2-aminobutyrate, or pyruvate had no effect on giant foxtail growth. However, these
metabolic intermediates combined with imazethpyr foliarly applied at 12 g/ha increased injury
to giant foxtail. The addition of 2-ketobutyrate to the spray solution appeared to overcome
the antagonistic-interaction between imazethpyr and fluazifop-butyl. Nomenclature:
Fluazifop-butyl, (i)-2-|4-[[5-(trifluoromethyl)—2—pyridimyl]oxy]phenoxy]propanic acid butyl
ester; imazethapyr, 2-[4,5-dihydro—4-methyl-4-(1-methylethyl)—5-oxo-lI-I-imidazol-2-yl]-5-
ethyl-3-pyridinecarboxylic acid; giant foxtail, Setariafaberi Herrm. # SETFA. Additional

index words: ACCase, acetolactate synthase, ALS, giant foxtail, SETFA.

16

17
INTRODUCTION

I mazethapyr is an imidazolinone herbicide identified as a potent inhibitor of ALS
(22). Imazethapyr has utility for weed control in soybean (Glycine max (L.) Merr.) and
imidazolinone-resistant corn (Zea mays L.) (l, 5, 7, 10, ll). Tank-mixtures of herbicides
which inhibit ALS with the aryloxyphenoxypropanoate and the cyclohexenedione herbicides
may result in loss or at least partial loss of grass control (17, 18). The basis for this
antagonism has not been determined but is not considered to involve uptake, translocation, or
molecular fate of the grass herbicide (16).

Two hypotheses have been proposed to explain the death of plants as a consequence
of ALS inhibition. The first is that inhibition of the ALS enzyme depletes the supply of the
amino acids leucine, isoleucine, and valine resulting in a starvation for these amino acids
(23). The second hypothesis is based on studies with microorganism and proposes that
inhibiting the ALS enzyme results in an accumulation of 2-ketobutyrate to toxic levels (15).
From a series of studies designed to disprove the second hypothesis, Shaner and Singh (21)
concluded that imazaquin injured corn as a consequence of starvation for valine and leucine
and that the accumulation of 2- aminobutyrate or 2-ketobutyrate was not accountable for the
herbicidal activity of imazaquin. The 2-ketobutyrate has a high vapor pressure and is very
volatile.

Hofgren et al. (12) failed to observe an accumulation of 2-ketobutyrate in potato
(Solanum tuberosum L. cv Desiree), a dicot, following treatment with the ALS inhibitor.

The aryloxyphenoxypropanoate and cyclohexenedione herbicides inhibit ACCase (4,
20). Substrates for this enzyme are pyruvate and acetate. The antagonistic interaction on the
control of broadleaf signalgrass (Bracharia platyphylla (Griseb.) Nash) by the tank mixture of
quizalofop and chlorimuron was significantly reduced by supplementing the nutrition of the
broadleaf signalgrass with L-leucine, L-isoleucine, and L—valine (9). Excess pyruvate that
might have accumulated from ALS inhibition by chlorimuron apparently is not involved in the

antagonistic interaction between quizalofop and chlorimuron (3).

18

Suggested bases for the antagonism observed between herbicides that inhibit ALS and
those that inhibit ACCase include a) the accumulation of intermediates as a consequence of
ALS inhibition that overcome the block imposed by the ACCase inhibitors, b) inhibition by
the ALS inhibitors of growth necessary for the phytoxic action of the ACCase inhibitors, and
c) the requirement for the synthesis of leucine, isoleucine, and valine for the phytotoxic
action of the ACCase inhbition (3, 8). Since Bjelk and Monaco (3) showed that excess
pyruvate did not appear to be involved in the interaction of the ALS inhibitors and ACCase
inhibitors, it was the objective of this study to determine whether 2-ketobutyrate was involved

in this antagonistic interaction.

MATERIALS AND METHODS
Evaluation of 2-ketobutyrate activity on giant foxtail in nutrient culture. Giant foxtail
(Setariafabr'ri Herrm.) was grown in a 224-ml styrofoam cups containing silica sand. Filter
paper was placed at the bottom of the cups to prevent the loss of sand and grass seed at
watering. Grass plants were maintained under greenhouse conditions at 2512 C with 16-h
day. Natural plus supplemental lighting with high pressure sodium lighting provided an

average of 1200 uE°m'2-sec'l

in the greenhouse. Grass plants were watered every other day
with Hoagland's nutrient solution with a pH of 6.6. After emergence, grass seedlings were
transplanted into 20—ml glass vials, three plants per vial. Vials were previously covered with
aluminum foil to prevent light penetration and algae growth. The vials contained 20 m1 of 0,
102, 103, and 10’4 M solutions of 2-ketobutyrate applied in Hoagland's nutrient solution,
and the pH of the solution was adjusted to 6.6. When the grass plants reached the three to
four-leaf stage, fluazifop-butyl was applied POST to the grass plants at rates of 26.7 an 53.4

1

g ai/ha, respectively, with 1% v/v crop oil concentrate . Herbicide treatments were applied

 

lHerbimax, a product of Loveland Industries, Inc., P. O. Box 906, Loveland, CO

80539.

19
with a continuous link belt sprayer at 193 kPa pressure and 230 um volume. The
experimental design was a completely randomized design with four replications, and the
experiment was repeated. Fourteen days after herbicide treatment, the three grass plants per
vial per replication were harvested and fresh weight taken. Following the analysis of
variance, means were separated using the Fisher's protected LSD at the 5% level of
significance.
The efi‘ect of potential modulators of imazethapyr activity on giant foxtail. Giant foxtail
was grown in 945-ml plastic pots containing Baccto potting media. The pots were placed in
the greenhouse at 2512 C with 16-h day. Natural plus supplemental lighting with high

1

prssure sodium lighting provided an average of 1200 ,uExm’2'sec' in the greenhouse. After

emergence, plants were thinned to three plants per pot. At time of treatment, grass plants

3 M were

were at the three-leaf stage. 2-Ketobutyrate, 2-aminobutrate, and pyruvate at 10'
dissolved in Hoagland's nutrient solution which served as a buffer and the pH of each
solution was adjusted to 6.6. The solutions were applied with 0.25% v/v Sylgard 309 about
10 to 20 minutes prior to imazethapyr application. Imazethapyr was applied POST to giant
foxtail at 12.9 g ai/ha with 1% v/v of crop oil concentrate. Treatments were applied with a
continuous link belt sprayer at 193 kPa pressure and 230 L/ha volume. A completely
randomized design was used and each treatment was replicated four times. Data presented
are the means of two experiments. Visual injury and shoot height 14 days after treatment
were used as measure of grass control. Visual injury rating scale of 0 to 100% was used with
complete death of grass plants receiving a rating of 100%. Following the factorial analysis of
variance, means were separated with Fisher's protected LSD at the 5% level of significance.
The effect of 2-ketobutyrate on the interaction of fluazifop-butyl and imazethapyr in
giant foxtail. Giant foxtail was grown in 945—ml plastic pots containing Baccto potting
media. The pots were placed in the greenhouse at 25 :2 C with 16-h day. Natural plus
supplemental lighting with high pressure sodium lighting provided an average of 1200

ptFxm'z'sec'l in the greenhouse. After emergence, plants were thinned to three plants per

20
pot. At time of treatment, grass plants were at the two- to three-leaf stage. 2-Ketobutyrate
at 10'3 M was dissolved in Hoagland's nutrient solution and the pH was adjusted to 6.6. 2-
Ketobutyrate was applied POST to grass plants about 5 to 10 minutes prior to herbicide
treatment with 0.25% v/v Sylgard 309. The herbicide treatments included imazethapyr at
12.9 g ai/ha and fiuazifop-butyl at 53.4 g ai/ha, respectively. Both herbicides were applied
POST to grass plants alone or in combination with 1% v/v of crop oil concentrate. The
treatments were applied with a continuous link belt sprayer at 193 kPa pressure and 230 Uha
volume. A completely randomized design was used and each treatment was replicated four
times. Visual injury and shoot height 14 days after treatment were taken as an indicator of
grass control. Data presented are the means of two experiments. Following the factorial
analysis of variance, means were separated with Fisher's protected LSD at the 5% level of
significance.
The elfect of Z-ketobutyrate on imazethapyr activity on soybean. Elgin 87 soybean was
grown in 945-ml plastic pots containing Baccto potting media. The pots were placed in the
greenhouse at 25 :2 C with 16-h day. Natural plus supplemental lighting with high pressure

sodium lighting provided an average of 1200 ,uE'm'z-sec'l

in the greenhouse. After
emergence, plants were thinned to three plants per pot. At time of treatment, soybean plants
were at the two trifoliolate leaf stage and about 20 cm tall. 2-Ketobutyrate at 10'3 M
concentration was dissolved in Hoagland's nutrient solution which served as a buffer and the
pH of each solution was adjusted to 6.6. 2-Ketobutyrate was applied with 0.25% v/v Sylgard
309 about 5 to 10 minutes prior to imazethapyr application. Imazethapyr was applied POST
to soybean plants at 51.5 g ai/ha with 1% v/v of crop oil concentrate. The herbicide and 2-
ketobutyrate treatments were applied with a continuous link belt sprayer at 193 kPa pressure
and 230 um volume. A completely randomized design was used and each treatment was
replicated six times. Data presented are plant height means from two experiments 14 days

after treatment. Following the factorial analysis of variance, means were separated with

Fisher's protected LSD at the 5% level of significance.

21
RESULTS AND DISCUSSION
Nutrient culture study.

F luazifop-butyl inhibited fresh weight accumulation of giant foxtail in the expected
rate dependent manner in the absence of 2-ketobutyrate (Table l). 2-Ketobutyrate also
inhibited giant foxtail growth in a rate dependent manner in the absence of POST application
of fiuazifop-butyl (Table 1). At the low rate of 2-ketobutyrate ((10'4 M) and the high rate of
fiuazifop-butyl (53.4 g/ha) an antagonistic interaction was very evident. Assuming they act at
the same target site and applying an additive interaction model, all combination values for the
10'3 M and 10'4 M 2-ketobutyrate plus either rate of fluazifop-butyl are greater than
expected indicating antagonism. Antagonism of ALS inhibiting herbicides where action may
result in accumulation of 2-ketobuyrate with ACCase inhibitors has been documented (6).
Butyrate has been documented as being phytotoxic (l4).

Foliar studies.

Foliar application of potential modulators of ALS inhibiting herbicides, 2-
ketobutyrate, 2-aminobutyrate, or pyruvate, had no effect on giant foxtail (Table 2). This is
consistent with the results of Shaner and Singh (21). However, if giant foxtail received both
imazethapyr and one of the potential modulators, injury to giant foxtail increased (Table 2).
These results could be interpreted to support the hypothesis of LaRossa et al. (15) that ALS
inhibiting herbicide exert their action through the accumulation of phytotoxic intermediates.

In a separate study the antagonistic interaction of the tank—mixture of imazethapyr and
fluazifop—butyl on giant foxtail injury was observed (Table 3). 2-Ketobutyrate applied
foliarily did not injure giant foxtail (Table 3) or soybean (Table 4), however, if both 2—
ketobutyrate and imazethapyr were applied, injury to giant foxtail was enhanced (Table 3) but
no injury to soybean was evident (Table 4). The application of fiuazifop-butyl, imazethapyr,
and 2-ketobutyrate resulted in giant foxtail injury similar to that obtained with imazethypyr
plus 2-ketobutyrate but slightly less than with fluazifop-butyl with or without 2-ketobutyrate

(I‘ able 3). These results raise the question whether the interaction between the ALS

22
inhibiting herbicides and the ACCase inhibiting herbicides involve potential modulators of
ALS activity. Banas et al. (2) have reported that ACCase inhibitors rapidly increase the ratio
of linoleniczoleic+linoleic fatty acids in wheat (Tn'ticum aestivum L.) roots. In contrast, the
ALS inhbitor, chlorsulfuron [2-chloro-N-[[(4-methoxy-6-methy1-l,3,5-triazin-2-
yl)amino]carbonyl]benzenesulfonamide] promoted oleic acid synthesis via the pyruvate
dehydrogenase complex in the chloroplasts of spinach (Spinacia oleracea L.) (13). This shift
was related to the presence of high levels of pyruvate. Although these opposing effects may
in part explain the antagonistic interaction of the ALS-inhibiting and ACCase inhibiting
herbicides it does not explain the modulating role of 2-ketyobutyrate or 2-aminobutyrate nor
does it consider the effect of ACCase inhibiting herbicides on membrane depolarization

documented by Shimabukuro and Hoffer (24).

23

Table l. The effect of 2-ketobutyrate and its role on fluazifop-butyl activity on giant foxtail

in nutrient culture.

 

2-ketobutyrate

 

 

 

 

53:31-22: Rate 0 10'4 M 10'3 M 10'2 M
g/ha Fresh weight mg/3 plants

Untreated 0 800 450 370 180

Fluazifop-butyl 26.7 240 210 190 50

Fluazifop—butyl 53.4 80 210 190 100

LSDODS 126

 

24

Table 2. The effect of potential modulators of imazethapyr action on giant foxtail.

 

 

Treatment Rate Visual injury Shoot height
% cm
Untreated 0 0 63
Pyruvate 10'3 M o 63
2-Ketobutyrate 10'3 M o 61
2-Aminobutyrate 10'3 M 0 59
Imazethapyra 1/4 x 48 38
Imazethapyr + pyruvate 1/4 X + 10’3 M 63 22
Imazethapyr + 2-ketobutyrate 1/4 X + 10'3 M 73 11
Imazethapyr + 2-aminobutyrate 1/4 X + 10'3 M 78 11
LSD0.05 4 5

 

aImazethapyr 1/4X=12.9 g ai/ha

Table 3. The effect of 2-ketobutyrate on the interaction of fluazifop-butyl and imazethapyr in
giant foxtail.

 

 

Treatment Rate Visual injury 14 DATa
g/ha %

Untreated 0.0 0
2-I(etobutyrateb 0
Imazethapyr 12.9 32
Fluazifop-butyl 53.4 78
Imazethapyr 12.9

+ fluazifop-butyl + 53.4 53
Imazethapyr 12.9 3

+ 2-ketobutyrate + 10' M 73
Fluazifop-butyl 53.4 3

+ 2-ketobutyrate + 10' M 79
Imazethapy 12.9

+ fluazifop-butyl + 53.

+ 2-ketobutyrate + 10' M 70
LSD0.05 3

 

aDAT - days after treatment.

3

b2-Ketobutyrate was applied at 10’ M concentration.

26

Table 4. The effect of 2-ketobutyrate on imazethapyr activity on Elgin 87 soybean.

 

 

Treatment Rate Plant height 14 DATa
cm

Untreated 0 46
Imazethapy rb l X 48
2-Ketobutyrate 10'3 M 50
Imazethapyr l X

+ 2-ketobutyrate + 10'3 M 49
LSD0.05 3

 

aDAT = days after treatment

bImazethapyr lX = 51.5 g ai/ha.

10.

27

LITERATURE CITED
Arnold, F. J ., W. A. Smith, and F. R. Taylor. 1994. Imazethapyr plus dicamba for
weed control in imi-com. Proc. North Cent. Weed Sci. Soc. 49:54.
Banas, A., 1. Johansson, G. Stenlid, and S. Stymne. 1993. The effect of haloxyfop
and alloxydim on growth and fatty acid composition of wheat roots. Swedish J.
Agric. Res. 23:55-65.
Bjelk, LA. and TJ. Monaco. 1992. Effect of chlorimuron and quizalofop on fatty
acid biosynthesis. Weed Sci. 40: 1-6.
Burton, J.D., .l.W. Gronwald, D.A. Somers, .l.A Connelly, B.G. Gengenback, and
D.L. Wyse. 1988. Inhibition of plant acetyl- Coenzyme A carboxylase by the
herbicide sethoxydim and haloxyfop. Biochem. Biophys. Res. Commmun. 148:1039-
1044.
Cartwell, .l. R., R. A. Liebl, and F. W. Slife. 1989. Imazethapyr for weed control
in soybeans (Glycine max). Weed Technol. 3:596-681.
Ferreira, K. L., .11. D. Burton, and H. D. Coble. 1995. Physiological basis for
antagonism of fluazifop-p by DPX-PE350. Weed Sci. 43: 184-191.
Frasier, A. L. and D. Penner. 1994. New opportunities for weed control using
imidazolinone resistant corn. Proc. North Cent. Weed Sci. Soc. 49:108.
Gerwick, B.C., P. Thompson, and R. Noveroske. 1988. Potential mechanisms in
antagonism with aryloxyphenoxypmpionate herbicides. Abstr. Weed Sci. Soc. Amer.
28: 100.
Hahn, K.L. and H.D. Coble. 1989. The effect of exogenously supplied amino acids
on the antagonistic interaction between quizalofop and chlorimuron. Abstr. Weed Sci.
Soc. Amer. 29:86.
Hart, S. E., L. M. Wax, .l. B. Carey, and D. L. Zinck. 1994. Imazethapyr based
weed control systems in imidazolinone resistant corn. Proc. North Cent. Weed Sci.

Soc. 49:63.

ll.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

28
Hayden, T. A. and S. Wendy. 1994. Weed control in imi-corn with imazethapyr
and imazethapyr combinations. Proc. North Cent. Weed Sci. Soc. 49:56.
Hofgren, R., B. Laber, I. Schuttke, A-K. Klonus, W. Streber, and H-D. Pohlenz.
1995. Repression of acetolactate synthase activity through antisense inhibition. Plant
Physiol. 1072469-477.
Homeyer, U., D. Schulze-Siebert, and G. Schultz. 1985. On the specificity of the
herbicide chlorsulfuron in intact spinach chloroplasts. Z. Naturforsch. 40c:917-918.
Lanyzagarta, A., J. M. de la Torre, and P. Alle. 1988. The effect of butyrate on cell
cycle progression in Alluim («pa root meristems. Plant Physiol. 72:775-781.
LaRossa, R.A., T.K. Van Dyke, and DR. Smulsky. 1987. Toxic accumulation of
2-ketobutyrate caused by inhibition of branched-chain amino acid biosynthetic enyme
acetolactate synthase in Salmonella typhimurium J. Bacteriol. 169:1372-1378.
Liebl, R. and AD. Worsham. 1987. Effect of chlorsulfuron on the movement and
fate of diclofop in Italian ryegrass (Lolium muln'florum) and wheat (Triticum
aestivum). Weed Sci. 35:623-628.
Minton. B. W., D. R. Shaw, and M. E. Kurtz. 1989. Postemergence grass and
broadleaf herbicide interactions for red rice (Oryza sativa) control in soybeans
(Glycine max.). Weed Technol. 32329-334.
Myers, F. and D. Coble. 1992. Antagonism of graminicide activity on annual grass
species by imazethapyr. Weed Technol. 62333-338.
Ray, T. B. 1984. Site of action of chlorsulfuron: inhibition of valine and leucine
biosynthesis in plants. Plant Physiol. 75:827-831.
Secor, J. and C. Cseke. 1988. Inhibition of acetyl-CoA carboxylase activity by
haloxyfop and tralkoxydim. Plant Physiol. 86:10-12
Shaner, D.L. and BK. Singh. 1993. Phytotoxicity of acetohydroxyacid synthase
inhibitors is not due to accumulation of 2-ketobutyrate and/or 2-aminobutyrate. Plant

Physiol. 103:1221-1226.

22.

23.

24.

29
Shaner, D. L., P. C. Anderson, and M. A. Stidham. 1984. Imidazolinones potent
inhibitors of acetohydroxyacid synthase. Plant Physiol. 76:545-546.
Sheel, D. and J .E. Casida. 1985. Acetohydroxyacid synthase inhibitors as
herbicides. In K. Neumann, W. Bary, E. Reinhart, eds. Primary and Secondary
Metabolism of Plant Cell Cultures. Springer Verlag, Berlin. pp. 344-355.
Shimabukuro, R. H. and B. L. Hoffer. 1995. Enantioners of diclofop-methyl and
their role in herbicide mechanisms of action. Pestic. Biochem. and Physiol.

51:68-82.

CHAPTER THREE
USE OF ORGANOPHOSPHATE INSECTICIDE LEVELS IN CORN SEEDLINGS
AS AN INDICATOR OF INJURY POTENTIAL FROM
POSTEMERGENCE APPLICATIONS OF
SULFONYLUREA HERBICIDES

Abstract. Postemergence applications of nicosulfuron and primisulfuron may injure corn
plants depending on the level of terbufos present in the young corn plants from prior
application of terbufos for corn rootworm control. Field studies were conducted in 1992 and
1993 to evaluate the interaction of nicosulfuron and primisulfuron with terbufos. Terbufos
was applied in-furrow at 0, 186, 375, and 750 g ai/ 100 m of row. N icosulfuron was applied
at 35 and 70 g ai/ha and primisulfuron at 40 and 80 g ai/ha when the corn was at the four-leaf
stage. Prior to herbicide application, plant samples both fresh and frozen from each
treatment were subjected to terbufos analysis. Terbufos levels in the plant samples were

1. The correlation coefficient for terbufos detected in

determined with a rapid detection kit
the shoot extract with observed herbicide injury to corn was 0.89 in 1992 and 0.94 in 1993.
Injury ratings showed a greater correlation with terbufos levels than did corn shoot height.
Thus, the rapid detection kit provided an efficient method to determine whether an injurious
terbufos-herbicide interaction might occur. Nomenclature: Nicosulfuron, 2-[[[[4,6-

dimethoxy-Z-pyrimidinyl)amino]carbonyl]amino]su1fonyl]-N ,N-dimethyl-3-

pyridinecarboxamide; primisulfuron, methyl 2-l[l[[4,6-bis(difluoromethoxy)-2-

 

1The Ticket, Agri Screen Product Line, Neogen Corp., Lansing, MI 48912.

30

31
pyrimidinyl]aminolcarbonyl]amino]sulfonyl]benzoate; terbufos, S-[(tert-butylthio)methyl]-
0,0-diethylphosphoridithioate; corn, Zea mays L.

Additional index words: Detection kit, interaction, nicosulfuron, primisulfuron, terbufos.

INTRODUCTION

The use of more than one pesticide on the same crop during the growing season has
become a frequent occurrence in modern crop production.

Despite the numerous advantages derived from the use of more than one chemical,
adverse effects to the crop may also occur. Several researchers have reported detrimental
interactions between the sulfonylurea herbicides, nicosulfuron and primisulfuron, with
terbufos (2, 3, 5, 6, 9, 11, 13, 15, 16, 17, 18, 19, 20, 21, 22). These herbicides were
introduced in 1991 for the control of grass and some broadleaf species in corn.

Northern and western corn rootworm can be very damaging in corn fields in
Michigan, especially in fields where corn follows corn. Thus, the use of a soil insecticide in
corn production is often necessary for the control of corn rootworm. The insecticide terbufos
is often the insecticide of choice for this purpose. Corn may be injured when nicosulfuron
and primisulfuron are applied to com fields that received a prior soil application of terbufos.
Corn injury symptoms range from slight growth inhibition and leaf curl to death of the corn
plants.

Terbufos absorbed by the corn plant and translocated to the shoot appears to interfere
with the metabolism of these two herbicides. Both the insecticide and the two herbicides
involved in this interaction are metabolized by mixed function oxidase.

The observed interaction may be affected by soil organic matter content, methods of
application of the insecticide, insecticide formulation, and environmental conditions (5, 16,
25), thus, making it difficult to predict the severity of the interaction. One way of assuring
safety to corn from the use of sulfonylurea herbicides after using the insecticide terbufos

would be assurance that the level of terbufos in the corn plants was below the critical level

32
that causes a detrimental interaction. The determination of that critical level in the corn
tissue could be provided by a low cost kit designed for that purpose that gave a color reaction
at the critical level plus a safety factor. Other procedures have also been used for detection
of organophosphate residue levels on leaf and soil surfaces to determine reentry into treated
fields (4, 7, 12, 23). These procedures include soil surface residue analysis (23) and leaf disc
analysis (4, 7, 12). However, these methods require laboratory manipulation and more time
to obtain the results.

The kit evaluated in this research was originally developed by the Midwest Research
Institute for the United States Army. The purpose was to provide the army with an easy and
reliable test to test the safety of drinking water in the field. This procedure required no
scientific experience, no instrumentation. In addition, secure storage in extreme weather
conditions and high sensitivity made the kit attractive for use in other areas such as
agriculture, food processing, and food production. This kit is based on a colorimetric
reaction carried out by the enzyme acetylcholinesterase (l)

The objective of this research was to evaluate a quick and easy-to-use kit that could
detect the presence of terbufos in corn seedlings at levels that result in corn injury from

POST applications of nicosulfuron and primisulfuron.

MATERIALS AND METHODS

‘Pioneer 3573' corn was planted at East Lansing, Michigan, in 1992 and 1993 in a
Spinks loamy sand soil containing 2.6% OM using a completely randomized block design.
The insecticide, terbufos, was applied in-furrow at planting at 186, 375, and 750 g/100 m of
row. Metolachlor [2-chloro-N-(2-ethy1-6-methylphenyl)-N-(2-methoxy-1-
methylethyl)acetamide] at 2.2 kg/ha and atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-I,3,5-
triazine-2,4-diamine] at 1.1 kg/ha were applied PRE. When the corn plants approached the
four—leaf stage, five plants from each of the four replications of each treatment were collected

and frozen for terbufos residue analysis in 1992 and 1993. In 1993 fresh samples were also

33
collected and analyzed. Samples for terbufos residue analysis were collected prior to POST
herbicide application.
POST herbicide application treatments included 35 (1x rate) and 70 (2x rate) g/ha
nicosulfuron and 40 (1x rate) and 80 (2x rate) g/ha primisulfuron. These herbicides were

applied with 0.25% nonionic adjuvant2

when com was at the four-leaf stage.

Corn injury was determined 14 DAT. Plant height was measured at 21 DAT.
Correlation coefficient was determined for both corn injury and plant height with the
concentration of terbufos detected in the plants. Analysis of variance for corn injury and
plant height was also conducted. After analysis of variance, means were separated by the
Fisher's protected LSD at the 5% level of significance. Data presented are the means of
three replications.

Terbufos detection procedure. Frozen corn plants were thawed. Physical pressure was
used to obtain an extract for analysis from both thawed and fresh samples. The plant extract
(1 ml) was partitioned with 1 ml hexane. Five drops of the hexane were placed on the test
ticket disc. A heat gun was used to evaporate the hexane. The activator ampule was placed
in the beaker with 20 ml of distilled water, broken with the glass rod, and the glass rod used
to place 3 drops of this solution on the test ticket disk. After 2 min., the two disks were
pressed together for 3 min. to allow color development. The development of blue color on
the test ticket disk was indicative of the absence of an organophosphate insecticide. The

terbufos concentration was determined visually by color comparison with a terbufos standard

curve (Figure l).

 

2X-77, nonionic surfactant is a mixture of alkylarylpolyoxyethylene glycols, free fatty
acids, and isopropanol marketed by Loveland Industries, Inc., P. O. Box 906, Loveland, CO

80539.

34
RESULTS AND DISCUSSION

An interaction between the sulfonylurea herbicides, nicosulfuron and primisulfuron,
and the insecticide terbufos was observed in corn field studies conducted in 1992 and 1993.
Corn injury was greater when nicosulfuron was applied at 1/2 and 1x rates to rows that
received 1/2 or 1x rate of terbufos (T able 1). Other researchers have reported injury to corn
caused by the nicosulfuron and terbufos interaction (5, 16, 25). The same trend of injury was
observed with primisulfuron applied at 1/2 and 1x rates with the greater injury resulting when
primisulfuron was applied to corn rows that received 1/2 and 1x rates of terbufos. Ketchersid
et al. (14) and Holshouser et al. (11) have also reported injury to corn resulting from the
primisulfuron and terbufos interaction. No difference in corn injury was observed between
the two herbicides at either rate applied to rows treated with terbufos. Corn height reduction
in 1992 was observed only when nicosulfuron was applied at 1x rate to corn plants that
received a prior soil application of 1x rate of terbufos (Table 1). Similar reductions were
observed when primisulfuron was applied at 1/2x rate to corn treated with IX of terbufos, but
not when primisulfuron was applied at 1x rate to corn treated with 1/4 or IX of terbufos. In
1993 corn height reduction was observed when nicosulfuron was applied at 1/2 or 1x to corn
that received 1/2 and 1x rates of terbufos, respectively. For the primisulfuron treatments,
corn height reduction was observed only when it was applied at 1/2x to corn plants treated
with 1/2 or 1x rates of terbufos. The correlation coefficients for plant height with the
terbufos level were -0.64 for 1992 and -0.66 for 1993, respectively (Figure 2).

Correlation coefficients obtained with the pesticide detector ticket kit of 0.90 in 1992
and 0.94 in 1993 between visual corn injury and terbufos levels in the corn plants at the time
of herbicide application. The regression analysis indicates that the terbufos levels in the corn
plants should be 3 ppm or less to assure visual corn injury of 10% or less (Figure 3).

These results show that a rapid detection kit can be used by growers to detect terbufos

levels present in the corn plants at the time of herbicide application. This will allow growers

35
to make a knowledge-based decision as to when or whether sulfonylurea herbicides can be

safely applied to corn fields that were treated with terbufos earlier in the season.

36

Table l. The effect of terbufos interaction with acetolactate synthase inhibiting herbicides on

 

 

 

corn
Herbicideb Injury Plant height 21 13mc
Insecticidea Rate treatments Rate 14 DAT 1992 1993
% ---------- cm ----------

Terbufos 0 0 83 144
Terbufos 1/4 0 88 130
Terbufos 1/2 3 75 140
Terbufos 1 x 3 79 135
Terbufos 0 Nicosulfuron 1/2 7 77 149
Terbufos 1/4 Nicosulfuron 1/2 21 79 133
Terbufos 1/2 N icosulfu ron 1/ 2 42 70 87
Terbufos 1 x Nicosulfuron 1/2 43 66 81
Terbufos 0 Nicosulfuron 1 x 13 80 144
Terbufos 1/4 Nicosulfuron 1 x 28 72 143
Terbufos 1/2 Nicosulfuron 1 x 42 63 101
Terbufos 1 x Nicosulfuron 1 x 49 59 98
Terbufos 0 Primisulfuron 1/2 13 79 137
Terbufos 1/4 Primisulfuron 1/2 23 73 140
Terbufos 1/2 Primisulfuron 1/2 43 67 117
Terbufos l x Primisulfuron 1/2 49 59 128
Terbufos 0 Primisulfuron 1 x 13 79 129
Terbufos 1/4 Primisulfuron 1 x 20 74 116
Terbufos 1/2 Primisulfuron l x 43 58 101
Terbufos 1 x Primisulfuron 1 x 53 65 100
LSDODS 7.6 15.6

 

aTerbufos was applied in furrow in rows of 1000 meters long at rates of 0, 186, 375, and 750
gr, respectively.

bHerbicide treatments included 35 (1x) and 70 (2x) g ai/ha nicosulfuron and 40 (1x) and 80
(1x) g ai/ha primisulfuron.

cPlant height values ar the means of five plants per row.

37

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43

LITERATURE CITED
Anonymous. 1988. Pesticide Detection Program. EnzyTec, Inc. Kansas City, MO.
41 p.
Ahrens, W. H. 1990. Corn variety response to DPX-9360 and CGA-136872 with
soil-applied insecticides. Proc. North Cent. Weed Sci. Soc. 45:34.
Baerg, R. J. and M. Barrett. 1993. Insecticide modifications of cytochrome P450
mediated herbicide metabolism. Proc. North Cent. Weed Sci. Soc. 48:70.
Blewett, T. C. and R. I. Krieger. 1990. Field leaf-test kit for rapid determination of
dislodgeable foliar residues of organophosphate and N-methyl carbamate insecticides.
Bull. Environ. Contam. Toxicol. 45212-124.
Diehl, K. E. and E. W. Stoller. 1991. Effect of soil organic matter on the
interaction between terbufos and nicosulfuron in corn. Proc. North Cent. Weed Sci.
Soc. 46:6.
Diehl, K. E. and E. W. Stoller. 1990. Interaction of organophosphate insecticides
with nicosulfuron and primisulfuron in corn. Proc. North Cent. Weed Sci. Soc.
45:31.
Gunther, F. A., W. G. Westlake, and J. H. Barkley. 1993. Establishing
dislodgeable pesticide residues on leaf surfaces. Bull. Environ. Contam. Toxicol.
9(4):243-249.
Hageman, L. H., J. D. Michael, and W. R. Scott. 1991. Update on the interactions
between nicosulfuron and organophosphate insecticides. Proc. North Cent. Weed
Sci. 46:46.
Harvey, R. G. 1992. MON-13900 for reducing field and sweet corn injury from
nicosulfuron and terbufos. Proc. North Cent. Weed Sci. Soc. 47:11.
Hatzios, K. K. and D. Penner. 1985. Interaction of herbicides with other

agrichemicals in higher plants. Rev. Weed Sci. 1:1-63.

11.

12.

13.

14.

16.

17.

18.

19.

20.

44
Holshouser, D. L., J. M. Chandler, and H. R. Smith. 1991. The influence of
terbufos on the response of five corn (Zea mays) hybrids to CGA-l36872. Weed
Technol. 5:165-168.
Iwata, Y., J. B. Knaak, R. C. Spear, and R. J. Foster. 1977. Worker reentry into
pesticide treated crops. 1. Procedure for the determination of dislodgeable pesticide
residues on foliage. Bull. Environ. Contam. Toxicol. 18(6):649-655.
Kapusta, G. and R. F. Krausz. 1992. Interaction of terbufos and nicosulfuron on
corn (Zea mays). Weed Technol. 62999-1003.
Ketchersid, M. L., J. M. Chandler, and M. G. Merkle. 1989. Factors affecting the
phytoxicity of CGA—l36872 to corn. Proc. South Weed Sci. Soc. 42:271.
Kwon, C. S. and D. Penner. 1992. The potential of piperonyl butoxide to enhance
weed control with postemergence application of sulfonylurea herbicides in corn.
Weed Sci. Soc. Abstr. 47:26.
Morton, C. A., R. G. Harvey, J. J. Kells, W. E. Lueschen, and V. A. Fritz. 1991.
Effect of DPX-V9360 and terbufos on field and sweet corn (Zea mays) under three
environments. Weed Technol. 5: 130-136.
Owen, M.D.K. 1991. Interaction of herbicides and insecticides used for corn
production. Proc. North Cent. Weed Sci. Soc. 46:44.
Peters, J. T., J. D. Mayonado, D. F. Loussaert, and R. E. Bulehler. 1991. MON
12000: Investigating the potential sulfonylurea herbicide/organophosphate soil
insecticide interaction. Proc. North Cent. Weed Sci. Soc. 46:34.
Pike, 1). R. and E. L. Knake. 1991. Interaction between DPX-V9360 and terbufos
applied to corn. Proc. North Cent. Weed Sci. Soc. 45:51.
Rahman, A. and K. J. Trevor. 1993. Enhanced activity of nicosulfuron in
combination with soil applied insecticides in corn (Zea mays). Weed Technol. 7:824-

829.

21.

22.

23.

24.

4S
Simarmata, M. and D. Penner. 1993. Protection from primisulfuron injury to corn
(Zea mays) and sorghum (Sorghum bicolor) with herbicide safeners. Weed Technol.
7: 174-179.
Smart, J. R., D. A. Mortensen, and L. J. Meinke. 1991. Method and timing of
insecticide application with nicosulfuron and primisulfuron. Proc. North Cent. Weed
Sci. Soc. 46:33.
Spener, W. F., Y. Iwata, W. W. Kilgore, and J. B. Knaak. 197. Worker reentry
into pesticide-treated rops. 11. Procedures for the determination of pesticide residues
on soil surface. Bull. Environ. Contam. Toxicol. 18(6):656-662.
Taylor, S. L., K. E. Diehl, D. M. Simpson, and E. W. Stoller. 1993. The effect of
nicosulfuron plus terbufos in vivo ALS activity in corn. Proc. North Cent. Weed Sci.
Soc. 48:71.
Williams, J. B. and R. G. Harvey. 1992. Influence of application taming,
adjuvants, rootworm insecticides, and hybrid on nicosulfuron injury to sweet corn.

Proc. North Cent. Weed Sci. Soc. 47:11.

SUMMARY

Greenhouse and field research was conducted to study the interaction of ALS
inhibitors with graminicides and insecticides. An antagonistic interaction between the
imidazolinone herbicide, imazethapyr, and several graminicides on annual grass control was
observed. The addition of ammonium sulfate to the spray solution helped to overcome the
antagonistic interaction.

The role of excess 2-ketobutyrate on the interaction of imazethapyr and fluazifop-
butyl was also evaluated. In sand cultivar studies, the addition of 2-ketobutyrate in the
nutrient culture solution caused reduction of annual grass fresh shoot weight confirming
suggested phytotoxicity of 2-ketobutyrate. Foliar application of fluazifop-butyl to plants
provided with 2-ketobutyrate resulted in a significant interaction. Metabolic intermediates
combined with imazethapyr foliarly applied increased injury to annual grass indicating that
they may play a modulating role in imazethapyr injury.

In a separate study, an antagonistic interaction between tank-mixture of imazethapyr
and fluazifop-butyl on giant foxtail control was observed. Foliar application of 2-
ketobutyrate alone did not injure giant foxtail or soybean. However, if both 2-ketobutyrate
and imazethapyr were applied, injury to giant foxtail was enhanced, but no injury to soybean
was observed. The injury to giant foxtail from the application of imazethapyr, fluazifop-
butyl, and 2-ketobutyrate was similar to that obtained with imazethapyr plus 2-ketobutyrate,
but slightly less than with fiuazifop-butyl with or without 2-ketobutyrate. These results raise
the question whether the interaction between the ALS and ACCase inhibiting herbicides

involve potential modulators of imazethapyr activity.

46

47
Field studies conducted to obtain the interaction of two sulfonylurea herbicides and
terbufos were conducted. The correlation coefficient between corn injury and terbufos levels
was greater than obtained with shoot height. A rapid pesticide detection kit was an efficient

method to detect terbufos levels present in the corn tissue at the time of herbicide application.

APPENDIX

APPENDIX
ANOVA Tables for Data

Chapter 1, Table 1

Imazethapyr x Fluazifop-butyl
Factor A Experiments 2
Factor B Imazethapyr, 0, 1/4X, 1/2X
Factor C Fluazifop-butyl, 0, 1/4X, 1/2X

 

Visual Injury ANOVA

 

 

 

 

 

 

Degrees of Sum of Mean

Code Source Freedom Squares Square F Value Prob
2 A 1 1953.13 1953.125 154.82 000
4 B 2 19752.08 9876.042 782.83 000
6 AB 2 168.75 84.375 6.69 .002
8 C 2 2027.08 1013.542 80.34 .000
10 AC 2 1064.58 532.292 42.19 000
12 BC 4 22583.33 5645.833 447.52 000
14 ABC 4 316.67 79.167 6.28 000

-15 Error 54 681.25 12.616

Coefficient of Variation = 6.02%

Shoot Height ANOVA
Degrees of Sum of Mean

Code Source Freedom Squares Square F Value Prob
2 A 1 974.61 974.611 35.90 .000
4 B 2 9254.72 4627.359 170.44 .000
6 AB 2 99.52 49.758 1.83 .169
8 C 2 2039.99 1019.995 37.57 .000
10 AC 2 587.55 293.75 10.82 .000
12 BC 4 5576.23 1394.059 51.35 .000
14 ABC 4 77.19 19.298 0.71

-15 Error 54 1466.08 27. 150

Coefficient of Variation = 19.37%

 

48

49

Chapter I, Table 1

Imazethapyr x Sethoxydim
Factor A Imazethapyr, 0, 1/4X, 1/2X
Factor B Sethoxydim, 0, 1/4X, 1/2X

 

Visual Injury ANOVA

 

 

 

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 2 250.52 125.260 247.82 .000
4 B 2 6.77 3.385 6.70 .002
6 AB 4 258.33 64.583 127.77 .000
-7 Error 63 31.84 0.505
Coefficient of Variation = 11.04%
Shoot Height ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 2 11159.41 5579.707 104.50 .000
4 B 2 1153.72 576.858 10.80 .000
6 AB 4 6968.93 1742.233 32.63 .000
-7 Error 63 3363.77 53.393

Coefficient of Variation = 30.32%

50

Chapter 1, Table 1

Imazethapyr x Quizalofop-ethyl
Factor A Experiments 2
Factor B Imazethapyr, 0, 1/4X, 1/2X
Factor C Quizalofop-ethyl, 0, 1/4X, 1/2X

 

Visual Injury ANOVA

 

 

 

 

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 12.50 12.500 1.10 .298
4 B 2 29675.69 14837.847 1308.15 .000
6 AB 2 577.08 288.542 25.44 .000
8 C 2 254.86 127.431 11.23 .000
10 AC 2 14.58 7.292 0.64
12 BC 4 26574. 31 6643.576 585 .72 .000
14 ABC 4 289.58 72.396 6.38 .000
-15 Error 54 612.50 11.343
Coefficient of Variation = 5.07%
Shoot Height ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 120.12 120.125 13.08 .000
4 B 2 15805.34 7902.670 860.59 .000
AB 2 778.52 389.260 42.39 .000
8 C 2 2026.38 1013.191 110.33 .000
10 AC 2 29.15 14.573 1.59 .213
12 BC 4 5220.45 1305.113 142.12 .000
14 ABC 4 208.27 52.068 5.67 .000
-15 Error 54 495.87 9.183

Coefficient of Variation = 15.26%

 

51

Chapter 1, Table 1

Imazethapyr x UBI-C4874
Factor A Experiments 2
Factor B Imazethapyr, 0, 1/4X, 1/2X
Factor C UB1-C4874, 0, 1/4X, 1/2X

 

Visual Injury ANOVA

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 0.68 0.681 0.05
4 B 2 35141.08 17570.542 1396.85 .000
6 AB 2 563.03 281.514 22.38 .000
8 C 2 13521.08 6760.542 537.46 .000
10 AC 2 55.53 27.764 2.21 .119
12 BC 4 7111.33 1777.833 141.34 .000
14 ABC 4 246.89 61.722 4.91 .001
-15 Error 54 679.25 12.579

Coefficient of Variation = 5.49%

 

 

Shoot Height ANOVA

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 7.67 7.670 0.36
4 B 2 16251.34 8125.670 386.45 .000
AB 2 743.26 371.628 17.67 .000
8 C 2 2102.03 1051.014 49.98 .000
10 AC 2 32.53 16.264 0.77
12 BC 4 5361.81 1340.451 63.75 .000
14 ABC 4 433.26 108.316 5.15 .001
-15 Error 54 1135.44 21.027

Coefficient of Variation = 22.15%

 

52

Chapter I, Table 2
Imazethapyr Formulations x Sethoxydim

Factor A Experiments 2
Factor B Imazethapyr formulations, 0, 1/4X, 1/2X
Factor C Sethoxydim, 0, 1/4X, 1/2X

 

Visual Injury ANOVA

 

 

 

 

 

 

Degrees of Sum of Mean

Code Source Freedom Squares Square F Value Prob
2 A 1 10219.56 10219.560 20.22 .000
4 B 2 22864.93 1 1432.463 22.62 .000
6 AB 2 1903.32 951.658 1.88 .156
8 C 6 7806.45 1301.075 2.57 021
10 AC 12 32637.78 2719.815 5.38 .000
12 BC 12 32637.78 2719.815 5.38 .000
14 ABC 12 6797.09 566.425 1.12 .349

-15 Error 126 63691.64 505.489

Coefficient of Variation = 73.56%

Shoot Height ANOVA
Degrees of Sum of Mean

Code Source Freedom Squares Square F Value Prob
2 A 1 8542.88 8542.881 956.80 .000
4 B 2 56310.46 27155,232 3153.39 .000
6 AB 2 508.08 254.042 28.45 .000
8 C 6 5318.12 886.353 99.27 .000
10 AC 6 2077.29 346.214 38.78 .000
12 BC 12 53661.95 4471.829 500.84 .000
14 ABC 12 1408.50 117.375 13.15 .000

-15 Error 126 1125.00 8.929

Coefficient of Variation = 5.40%

 

Chapter 1, Table 2

53

Imazethapyr Formulations x Fluazifop-butyl

Factor A
Factor B
Factor C

Experiments 2

Imazethapyr formulations, 0, 1/4X, 1/2X
Fluazifop-butyl, 0, l/4X, 1/2X

 

Visual Injury ANOVA

 

 

 

 

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 54.86 54.857 2.84 .094
4 B 2 63819.48 31909.738 1650.50 .000
AB 2 910.43 455.214 23.55 .000
8 C 6 13447.56 2241.260 _ 115.93 .000
10 AC 6 3009.23 501.538 25.94 .000
12 BC 12 46832.44 3902.703 201 . 86 .000
14 ABC 12 596.49 49.707 2.57 .004
-15 Error 126 2436.00 19.333
Coefficient of Variation = 9.61%
Shoot Height ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 6.48 6.482 0.17
4 B 2 24022.90 12011.448 310.62 .000
6 AB 2 38.48 19.242 0.50
8 C 6 5717.93 952.989 24.64 .000
10 AC 6 580.88 96.814 2.50 .025
12 BC 12 11607.97 967.331 25.02 .000
14 ABC 12 465.64 38.803 1.00 .449
-15 Error 126 487235 38.669

Coefficient of Variation = 21.37%

 

Chapter I, Table 2

Imazethapyr Formulations x UBI-C4874
Factor A
Factor B

Experiments 2

Imazethapyr formulations, 0, 1/4X, 1/2X
FactorC UBI-C4874, 0, 1/4X, 1/2X

 

Visual Injury ANOVA

 

 

 

 

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 1178.72 1178.720 402.76 .000
4 B 2 134106.25 67053.125 22911.71 .000
6 AB 2 2937.80 1468.899 501.92 .000
8 C 6 1628.87 271.478 92.76 .000
10 AC 6 647.32 107.887 36.86 .000
12 BC 12 32954.17 2746.181 938.36 .000
14 ABC 12 626.79 52.232 17.85 .000
-15 Error 126 368.75 2.927
Coefficient of Variation = 2.91%
Shoot Height ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 74.53 74.533 2.45 .120
B 2 44189.97 22094.987 725.26 .000
AB 2 59.45 29.725 .098
8 C 6 346.52 57.753 1.90 .086
10 AC 6 46.22 7.704 0.25
12 BC 12 5561.89 463.491 15.21 .000
14 ABC 12 445.90 37.158 1.22 .276
-15 Error 126 838.60 30.465

Coefficient of Variation = 23.78%

 

Chapter I, Table 3

55

Imazethapyr x UBI-C4874 x Ammonium sulfate

Factor A
Factor B

Factor D Ammonium sulfate, 0, 1135 gr/ha

Experiments 2

Imazethapyr, 0, 1/4X, 1/2X
Factor C UBI-C4874, 0, 1/4X, 1/2X

 

Visual Injury ANOVA

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 6.25 6.250 0.30
4 B 1 7367.36 7367.361 349.75 .000
6 AB 1 850.69 850.694 40.38 .000
8 C 2 61626.04 30813.02] 1462.77 .000
10 AC 2 594.79 297.396 14.12 .000
12 BC 2 1335.76 667.882 31.71 .000
14 ABC 2 308.68 154.340 7.33 .001
16 D 2 2879.17 1439.583 68.34 .000
18 AD 2 1266.67 633.333 30.07 .000
20 BD 2 5272.22 2636.111 125.14 .000
22 ABC 2 301.39 150.694 7.15 .001
24 CD 4 40422.92 10105.729 479.74 .000
26 ACD 4 366.67 91.667 4.35 .002
28 BCD 4 971.53 242.882 11.53 .000
30 ABCD 4 948.61 237.153 11.26 .000
-31 Error 108 2275 .00 21.065

Coefficient of Variation = 6.91%

 

56

 

Shoot Height ANOVA

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 59.16 59.162 2.24 .137
4 B 1 1910.42 1910.418 72.45 .000
6 AB 1 12.31 12.308 0.47
8 C 2 16013.99 8006.995 303.68 .000
10 AC 2 7.53 3.765 0.14
12 BC 2 1700.67 850.335 32.25 .000
14 ABC 2 220.37 110.184 4.18 .017
16 D 2 1889.12 944.562 35.82 .000
18 AD 2 4.77 2.384 0.09
20 BC 2 877.32 438.661 16.64 .000
22 ABD 2 22.07 11.033 0.42
24 CD 4 8514.87 2128.717 80.73 .000
26 ACD 4 70. 10 17.526 0.66
28 BCD 4 890.71 222.677 8.45 .000
30 ABCD 4 269.69 67.422 2.56 .042
-31 Error 108 2847.63 26. 367

Coefficient of Variation = 27.60%

 

Chapter I, Table 3

57

Imazethapyr x Fluazifop-butyl x Ammonium sulfate

Factor A
Factor B
Factor C

Experiments 2
Imazethapyr, 0, 1/4X, 1/2X

FIuazifop-butyl, 0, 1/4X, 1/2X
Factor D Ammonium sulfate, 0, 1135 gr/ha

 

Visual Injury ANOVA

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 291.84 291.840 62.26 .000
4 B 1 16362.67 16362.674 3490.70 .000
6 AB 1 291.84 291.840 62.26 .000
8 C 2 30064.93 15032.465 3206.93 .000
10 AC 2 287.85 143.924 30.70 .000
12 BC 2 60.76 30.382 6.48 .002
14 ABC 2 208.68 104.340 22.26 .000
16 D 2 7325.35 3662.674 781.37 .000
18 AD 2 887.85 443.924 94.70 .000
20 BD 2 13069.10 6434.549 1394.04 .000
22 ABD 2 906.60 453.299 96.70 .000
24 CD 4 35664.24 8916.059 1902.09 .000
26 ACD 4 2274.65 568.663 121.31 .000
28 BCD 4 1199.65 299.913 63.98 .000
30 ABCD 4 847.57 211.892 45.20 .000
-31 Error 108 506.25 4.687

Coefficient of Variation = 3.77%

 

58

 

Shoot Height ANOVA

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square P Value Prob
2 A 1 2.75 2.750 0.10
4 B 1 5714.10 5714.100 199.60 .000
6 AB 1 8.95 8.950 0.31
8 C 2 9819.59 4909.793 171.51 .000
10 AC 2 45.00 22.502 0.79
12 BC 2 383.82 191.909 6.70 .001
14 ABC 2 149.63 74.813 2.61 .077
16 D 2 1368.10 484.052 23.89 .000
18 AD 2 305.16 152.581 5.33 .006
20 BD 2 3074.98 1537.489 53.71 .000
22 ABD 2 62.11 31.055 1.08 .341
24 CD 4 11182.31 2795.579 97.65 .000
26 ACD 4 411.39 102.847 3.59 .008
28 BCD 4 320.46 80.115 2.80 .029
30 ABCD 4 196.12 49.029 1.71 .152
-31 Error 108 3091 .78 28.628

Coefficient of Variation = 24.51%

 

Chapter I, Table 3

Imazethapyr x Sethoxydim x Ammonium sulfate

Factor A
Factor B
Factor C

Experiments 2
Imazethapyr, 0, 1/4X, 1/2X
Sethoxydim, 0, 1/4X, 1/2X
Factor D Ammonium sulfate, 0, 1135 gr/ha

 

Visual Injury ANOVA

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 3500.69 3500.694 311.81 .000
4 B 1 26136.11 26136.111 2328.00 .000
6 AB 1 506.25 506.250 45.09 .000
8 C 2 27638.54 13819.271 1230.91 .000
10 AC 2 264.93 132.465 11.80 .000
12 BC 2 114.93 57.465 5.12 .007
14 ABC 2 9.37 4.687 0.42
16 D 2 9129.17 4564.583 406.58 .000
18 AD 2 372.22 186.111 16.58 .000
20 BD 2 9343.06 4671.528 416.10 .000
22 ABD 2 54.17 27.083 2.41 .094
24 CD 4 44954.17 11238.542 1001.04 .000
26 ACD 4 202.78 50.694 4.52 .002
28 BCD 4 234.03 58.507 5.21 .000
30 ABCD 4 452.08 113.021 10.07 .000
-31 Error 108 1212.50 11.227

Coefficient of Variation = 5.12%

 

60

 

Shoot Height ANOVA

 

 

Degrees of Sum of Mean

Code Source Freedom Squares Square F Value Prob
2 A 1 926.70 926.695 41.16 .000
4 B 1 11687.41 11687.412 519.12 .000
6 AB 1 724.96 724.956 32.20 .000
8 C 2 11213.95 5606.976 249.04 .000
10 AC 2 80.75 40.377 1.79 .171
12 BC 2 144.17 72.083 3.20 .044
14 ABC 2 14.63 7.313 0.32
16 D 2 1198.26 599.130 26.61 .000
18 AD 2 63.22 31.608 1.40 .250
20 BD 2 6197.73 3098.864 137.64 .000
22 ABD 2 108.95 54.474 2.42 .093
24 CD 4 16542.41 4135.602 183.69 .000
26 ACD 4 478.78 119.696 5.32 .000
28 BCD 4 107.71 26.928 1.20 .316
30 ABCD 4 360.13 90.031 4.00 .004

-31 Error 108 2431.51 22.514

Coefficient of Variation = 21.51%

 

Chapter 2, Table 4
Fluazifop-butyl x 2-ketobutyrate

61

 

 

 

Factor A Experiments 2
Factor B 2-ketobutyrate, 0, 102, 103, 10'4 molar
Factor C Fluazifop-butyl, 0, 1/4X, 1/2X
Fresh Weight ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 0.14 0.145 9.29 .003
4 B 3 0.86 0.288 18.44 .000
6 AB 3 0.63 0.210 13.45 .000
8 C 2 1.84 0.919 58.92 .000
10 AC 2 0.34 0.169 10.86 .000
12 BC 6 0.98 0.164 10.52 .000
14 ABC 6 1.03 0.172 11.00 .000
-15 Error 72 1.12 0.016

Coefficient of Variation = 48.84%

 

62

Chapter 2, Table 5

Imazethapyr x Pyruvate x 2-ketobutyrate x 2-aminobutyrate
Factor A Experiments 2
Factor B Imazethapyr, 0, 1/3X, 1/ X
Factor C Modulators, 0, 10' , 10' , 10'4 molar

 

Visual Injury ANOVA

 

 

 

 

 

 

Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 0.39 0.391 0.02
4 B 1 67925.39 67925.391 3548.76 .000
AB 1 0.39 0.391 0.02
8 C 3 2138.67 712.891 37.24 .000
10 AC 3 863.67 287.891 15.04 .000
12 BC 3 2138.67 712.891 37.24 .000
14 ABC 3 863.67 287.891 15.04 .000
-15 Error 48 918.75 19.141
Coefficient of Variation = 13.43%
Shoot Height ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 712.22 712.223 29.84 .000
4 B 1 26875.50 26875.504 1 125.98 .000
6 AB 1 133.69 133.691 5.60 .022
8 C 3 2400.48 800.160 33.52 .000
10 AC 3 360.04 120.014 5.03 .004
12 BC 3 1470.01 490.004 20.53 .000
14 ABC 3 665.95 221.983 9.30 .000
-15 Error 48 1 145.69 23.868

Coefficient of Variation = 11.95%

 

 

Chapter 2, Table 6

Imazethapyr x Quizalofop-ethyl

63

 

 

 

Factor A Experiments 2
Factor B Fluazifop-butyl, 0, 1/4X, 1/2X
Factor C Imazethapyr, 0, 1/4X 1/2X
Factor D 2-ketobutyrate, 0, 10'3 molar
Visual Injury ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 58653.13 58653. 125 1025.43 000
4 B 1 13819.53 13819.53] 241.61 000
6 AB 1 41328.13 41328.125 722.54 .000
8 C 1 9625.78 9625.781 168.29 .000
10 AC 1 450.00 450.000 7.87 005
12 BC 1 8613.28 8613.281 150.59 000
14 ABC 1 703.13 703.125 12.29 .000
16 D 1 413.28 413.281 7.23 .008
18 AD 1 28.13 28.125 0,49
20 BD 1 282.03 282.031 4.93 .028
22 ABD 1 78.13 78.125 1.37 .245
24 CD 1 225.78 225.781 3.95 .049
26 ACD 1 112.50 112.500 1.97 .163
28 BCD 1 175.78 175.781 3.07 .082
30 ABCD 1 78.13 78.125 1.37 .245
~31 Error 1 12 6406.25 57.199

Coefficient of Variation = 15.20%

 

 

64

 

 

 

Shoot Height ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 18540.16 18540. 158 687.73 .000
4 B 1 11829.14 11829.143 438.79 .000
6 AB 1 14185.60 14185.596 526.20 .000
8 C 1 379.85 379.846 14.09 .000
10 AC 1 104.22 104.221 3.87 .051
12 BC 1 196.27 196.268 7.28 .008
14 ABC 1 14.78 14.783 0.55
16 D 1 115.33 115.330 4.28 .040
18 AD 1 167.67 167.674 6.22 .014
20 BD 1 34.55 34.549 1.28 .260
22 ABD 1 0.56 0.564 0.02
24 CD 1 95.39 95.93 3.54 .062
26 ACD 1 184.08 184.080 6.83 .010
28 BCD 1 68.30 68.299 2.53 .114
30 ABCD 1 4.69 4.689 0.17
~31 Error 1 12 3019.34 26.958

Coefficient of Variation = 18.76%

 

65

Chapter 2, Table 7
Imazethapyr x 2-ketobutyrate
Factor A Experiments 2
Factor B Imazethapyr, 0, 1X
Factor C 2-ketobutyrate, 0, 10’3 molar

 

 

 

Shoot Height ANOVA
Degrees of Sum of Mean

Code Source Freedom Squares Square F Value Prob
2 A 1 3064.01 3064.005 438.17 .000
4 B 1 78.80 78.797 11.27 .001
6 AB 1 24.80 24.797 3.55 .066
8 C 1 2.76 2.755 0.39
10 AC 1 1.17 1.172 0.17
12 BC 1 29.30 29.297 4.19 .047
14 ABC 1 2.30 2.297 0.33

~15 Error 40 279.71 6.993

Coefficient of Variation = 5.50%

 

Chapter 3, Table 1
Terbufos x Herbicides

66

 

 

 

 

 

 

 

Factor A Years, 2
Factor B Terbufos, 0, 1/4X, 1/2X, 1X
Factor C Herbicides, 0, 1/4X, 1/2X, 1X
Visual Injury ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square P Value Prob
2 A 1 603.01 603.008 13.77 .000
4 B 3 18462.43 6154.142 140.50 .000
6 AB 3 333.09 111.031 2.53 .062
8 C 4 17290.87 4322.717 98.68 .000
10 AC 4 1999.53 499.883 11.41 .000
12 BC 12 3812.20 317.683 7.25 .000
14 ABC 12 808.20 67.350 1.54 .128
-15 Error 78 3416.65 43.803
Coefficient of Variation = 26.03%
Shoot Height ANOVA
Degrees of Sum of Mean
Code Source Freedom Squares Square F Value Prob
2 A 1 603.01 603.008 13.58 .000
4 B 3 18462.43 6154.142 138.61 .000
6 AB 3 333.09 111.031 2.50 .065
10 AC 4 1999.53 4322.717 97.36 .000
12 BC 12 3812.20 317.683 7.16 .000
14 ABC 12 808.20 67.350 1.52 .135
-15 Error 80 3552.00 44.400

Coefficient of Variation

= 26.21%

 

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