Broadleaf Weed Control and Crop Safety with Premixed Pyrasulfotole and Bromoxynil in Winter Wheat

doi:10.4236/ajps.2012.311195

Paper Menu >>

Journal Menu >>

American Journal of Plant Sciences, 2012, 3, 1613-1618

http://dx.doi.org/10.4236/ajps.2012.311195 Published Online November 2012 (http://www.SciRP.org/journal/ajps)

1613

Broadleaf Weed Control and Crop Safety with Premixed

Pyrasulfotole and Bromoxynil in Winter Wheat

Seshadri S. Reddy1*, Phillip W. Stahlman1, Patrick W. Geier1, Dallas E. Peterson2

1Agricultural Research Center, Kansas State University, Hays, USA; 2Department of Agronomy, Kansas State University, Manhattan,

USA.

Email: *[email protected]

Received August 4th, 2012; revised September 17th, 2012; accepted October 15th, 2012

ABSTRACT

For more than two decades acetolactate synthase (ALS) inhibiting herbicides have been the major weed control tools in

winter wheat which resulted in selection of resistant weeds to those herbicides. Premixed pyrasulfotole & bromoxynil

(Huskie®) is a relatively new herbicide registered for use in wheat in 2008. Pyrasulfotole inhibits 4-hydoxyphenylpy-

ruvate dioxygenase (HPPD) enzyme in susceptible plants and is the first significant new mode of action for use in cere-

als in more than two decades. Field experiments were conducted from 2007 to 2010 at two locations in Kansas, USA to

test the efficacy of pyrasulfotole & bromoxynil for broadleaf weed control and crop safety in winter wheat. Treatments

included pyrasulfotole & bromoxynil alone at 253 g·ai·ha−1 and tank mixtures of pyrasulfotole & bromoxynil at 207

g·ai·ha−1 with MCPA at 280 g·ai·ha−1, dicamba at 140 g·ai·ha−1 or metsulfuron-methyl at 4.2 g·ai·ha−1. Herbicides were

applied postemergence in fall and spring seasons. Pyrasulfotole & bromoxynil alone or in combination with tank-mix

partners, regardless of application time, controlled flixweed, blue mustard, bushy wallflower and field pennycress 98%

or more. Henbit control was better when pyrasulfotole & bromoxynil treatments were applied in fall than spring (≥98%

vs ≥67%). Pyrasulfotole & bromoxynil alone applied in spring was not effective on wild buckwheat, but tank mixing

with dicamba or metsulfuron-methyl controlled wild buckwheat 84% or more. Pyrasulfotole & bromoxynil alone or in

tank mixtures caused little (≤7%) or no injury to wheat and the injury did not influence wheat grain yields. Based on

excellent control of broadleaf weeds evaluated, pyrasulfotole & bromoxynil is an alternative tool to control

ALS-inhibitor resistant weeds in winter wheat. Fall season application and tank mixing with other herbicides are desir-

able for effective broad spectrum weed control.

Keywords: Huskie®; Henbit; Blue Mustard; Flixweed; Bushy Wallflower; Field Pennycress; Wild Buckwheat;

Postemergence; Injury

1. Introduction

Wheat (Triticum aestivum L.) is the most important ce-

real crop in the USA, where it was planted on 23 million

ha in 2012 [1]. Most of the wheat grown in the USA is

winter wheat (17 million ha). Kansas state ranks first in

winter wheat cultivation (4 million ha) in the USA [1].

Winter wheat is not a good competitor with some broad-

leaf weeds even when wheat emerges before weeds [2].

Common weeds found in winter wheat in the US are blue

mustard [Chorispora tenella (Pallas) DC.], henbit (La-

mium amplexicaule L.), flixweed [Descurainia sophia

(L.) Webb. Ex Prantl], bushy wallflower (Erysimum re-

pandum L.), field pennycress (Thlaspi arvense L.), wild

buckwheat (Polygonum convolvulus), shepherd’s purse

[Capsella bursa-pastoris (L.) Medik.], and pinnate tan-

symustard [Descurainia pinnata (Walt.) Britt.]. Their

interference can cause significant yield reduction in win-

ter wheat. Season-long competition of 11, 33, and 98

blue mustard plants·m−2 reduced wheat grain yields by

28%, 42%, and 51%, respectively [2]. Conley and Brad-

ley (2005) [3] reported yield reductions of 13 and 38%

because of henbit interference at 82 and 155 plants·m−2,

respectively. Northam et al. (1993) [4] also reported

wheat grain yield loss of 48% with 221 henbit plants·m−2.

Bushy wallflower at 272 plants·m−2 reduced wheat yields

by 25% [5]. Hence, winter annual broadleaf weed control

is very important for successful wheat production.

For more than two decades acetolactate synthase

(ALS)-inhibiting herbicides have been primary herbi-

cides used in winter wheat, however continuous usage of

those herbicides led to selection of ALS-inhibitor resis-

tant weeds. Currently 126 ALS-inhibitor resistant weed

species have been reported worldwide; 45 in the USA [6].

Bushy wallflower and flixweed, two common broadleaf

*Corresponding author.

Broadleaf Weed Control and Crop Safety with Premixed Pyrasulfotole and Bromoxynil in Winter Wheat

1614

weeds in winter wheat, were reported ALS-inhibitor re-

sistant in 2005 and 2006, respectively in Kansas [6-8].

Rotating herbicides with different modes of action can

avoid selection for weeds biotypes that are resistant to

certain herbicides. Hence, there is a need for herbicides

with alternative modes of action to ALS-inhibitor herbi-

cides in wheat.

Pyrasulfotole is a new herbicidal active ingredient be-

longing to the pyrazoles family of herbicides. Pyrasul-

fotole inhibits 4-hydoxyphenylpyruvate dioxygenase

(HPPD) and blocks the pathway of prenylquinone bio-

synthesis in plants [9]. This leads to decreased levels of

plastoquinone in plant tissue and reduced photosynthetic

yield [10]. Indirect inhibition of phytoene desaturase as a

consequence of blocked plastoquinone biosynthesis sub-

sequently leads to a decrease in carotenoids [11] and

consequently prevents stabilization of the photosynthetic

apparatus so that chlorophyll molecules are destroyed by

excessive light energy. Inhibition of HPPD also prevents

biosynthesis of tocopherols that leads to reduced vitamin

E synthesis, which means loss of protection against oxi-

dative stress and against photo inactivation of the photo-

synthesis apparatus. The whole process will result in

typical bleaching symptoms in the newly developing

leaves during the first week after application. These

bleaching symptoms progress toward necrosis and sus-

ceptible plants generally die within two to three weeks

after treatment. Pyrasulfotale is the first significant com-

pound with a new mode of action for broadleaf weed

control in wheat, barley and triticale in more than 20

years.

The prepacked mixture of pyrasulfotole & bromoxynil

(Huskie®, Bayer CropScience, P.O. Box 12014, 2 T.W.

Alexander Drive, Research Triangle Park, North Caro-

lina 27709, USA) received US registration for use in

wheat in 2008. Bromoxynil belongs to the nitrile group

and inhibits photosynthesis at photosystem II in suscep-

tible plants. The premix also contains the safener me-

fenpyr-diethyl. The recommended dose of pyrasulfotole

& bromoxynil is 207 to 282 g·ai·ha−1 and recommended

stage of application in wheat is first leaf to flag leaf

emergence. The herbicide label recommends tank mixing

pyrasulfotole & bromoxynil with dicamba, MCPA, met-

sulfuron-methyl or 2,4-D for broad spectrum weed con-

trol. Currently not much information on use of pyrasul-

fotole & bromoxynil in winter wheat is available. The

objectives of the study were 1) to evaluate premixed

pyrasulfotole & bromoxynil with and without other her-

bicides for efficacy and safety in winter wheat and 2) to

determine the optimum time for its application.

2. Material and Methods

Field experiments were conducted for two years near

Hays (2007-2009) and for three years near Manhattan

(2007-2010) in Kansas in the central USA. Soil charac-

teristics of the sites are given in Table 1. Experimental

design was a randomized complete block with four treat-

ment replications. The pyrasulfotole & bromoxynil pre-

mix was tested alone or in tank mix combinations with

other herbicides applied postemergence (POST) at two

timings. The rate of pyrasulfotole & bromoxynil used was

253 g·ai·ha−1 without other herbicides and 207 g·ai·ha−1

when tank mixed. Tank mixture partners tested were

MCPA ester at 280 g·ai·ha−1, dicamba at 140 g·ai·ha−1,

Table 1. Soil characteristics and planting and spraying information, Hays and Manhattan, KS, 2007-2010.

Hays, KS Manhattan, KS

2007-2008 2008-2009 2007-2008 2008-2009 2009-2010

Soil type Roxbury silt loam Crete silty clay loamReading silt loam Reading silt loam Reading silt loam

Soil pH 7.7 6.3 5.7 5.7 5.7

Organic matter (%) 2.5 2 2.9 2.9 2.9

Wheat cultivar Danby KS08HW35-1 Overley Overley Fuller

Seed rate (kg·ha−1) 73 63 78 78 78

Planting date 10/02/2007 10/01/2008 10/11/2007 10/08/2008 10/19/2009

Row spacing (cm) 25 25 25 25 19

Plot size 2.5 × 6.7 2.5 × 6.7 1.9 × 6 1.9 × 6 1.9 × 6

Fall-POST spray date 11/04/2007 11/07/2008 11/27/2007 11/25/2008 12/04/2009

Spring-Post spray date 03/13/2008 03/16/2009 03/28/2008 03/17/2009 03/29/2010

Broadleaf Weed Control and Crop Safety with Premixed Pyrasulfotole and Bromoxynil in Winter Wheat 1615

and metsulfuron-methyl at 4.2 g·ai·ha−1. A commercial

standard of premixed triasulfuron & dicamba at 165

g·ai·ha−1 and a non-treated control were also included in

the study. Non-ionic surfactant at 0.5% v/v and 28% urea

ammonium nitrate at 4.7 L·ha−1 were included with all

herbicide treatments. Treatments were applied poste-

mergence to winter wheat at two timings, i.e. fall poste-

mergence (fall-POST) and spring postemergence (spring-

POST). Herbicides were applied broadcast using back-

pack or tractor-mounted plot sprayers, calibrated to de-

liver 121 to 139 L·ha−1 at 172 to 207 kPa. Henbit, flix-

weed and blue mustard were predominate weed species

at Hays, and henbit, flixweed, bushy wallflower, field

pennycress and wild buckwheat were predominate at

Manhattan. Wheat variety, seeding rate, plot size, row

spacing, planting and application dates are presented in

Table 1. Generally, wheat was 5 - 10 cm tall with 1 - 2

tillers at fall-POST application and 7.5 - 15 cm tall with

2 - 5 tillers at spring-POST application. Likewise, except

wild buckwheat, weeds were 1 - 2.5 cm tall at fall-POST

and 2.5 - 7.5 cm at spring-POST application. Wild

buckwheat had not emerged by the time of fall-POST

applications at Manhattan; they emerged in spring and

were at cotyledon to 4 leaf stage when spring-POST

treatments were applied.

Weed control and crop injury were rated based on

composite visual estimations of density reduction, growth

inhibition, and foliar injury on a scale of 0 (no effect) to

100 (plant death). Henbit, flixweed and blue mustard

control ratings were determined 195 to 224 days after

planting (DAP) at Hays. Similarly, henbit, flixweed,

bushy wallflower and field pennycress control ratings

were determined 190 to 206 DAP at Manhattan. Wild

buckwheat control was determined 236 to 258 DAP at

Manhattan. Wheat injury was visually assessed 2 weeks

after fall-POST and spring-POST applications at each

location. Grain yield was determined by harvesting the

six center rows of each plot with a plot combine and ad-

justing seed weight to 12.5% moisture content. Yields

were not determined at Manhattan in 2008 due to hail

damage. Data were analyzed using the general linear

model procedure of SAS (Statistical Analysis Systems

Institute, Cary, NC, USA) and means were separated at

the 5% significance level using Fisher’s protected LSD.

Percent weed control and wheat injury were arcsine

transformed before analysis. The control treatment was

omitted from weed control and crop injury analyses, but

included in the analysis of wheat grain yield. Because

there was significant year by location by treatment inter-

action for henbit and flixweed control data are presented

year wise for each location (Table 2). Year by treatment

interactions were significant for blue mustard, bushy

wallflower and field pennycress and hence data are pre-

sented year wise for respective locations. Wild buck-

wheat control ratings at Manhattan were pooled over

years 2007-2008 and 2008-2009 because year by treat-

ment interaction was non-significant. Wheat injury rating

were pooled over years and presented separately for each

site because site by treatment interactions were significant.

3. Results and Discussion

3.1. Weed Control

3.1.1. Henb it

In 2007-2008, at Hays, fall-POST application of all her-

bicides controlled henbit better than spring-POST treat-

ments (Ta b le 3 ). Complete control of henbit was achieved

with all fall-POST treatments. Among spring-POST

treatments henbit control was lowest with tank mixture

of pyrasulfotole & bromoxynil + metsulfuron-methyl

(86%) and premixed triasulfuron & dicamba (84%).

Henbit control was essentially complete, regardless of

herbicide or application timing at Hays in 2008-2009. At

Manhattan, all pyrasulfotole & bromoxynil treatments

applied fall-POST controlled henbit ≥ 98%, but control

varied significantly among spring-POST treatments (67% -

100%). Lowest henbit control was observed with triasul-

furon & dicamba applied either fall-POST or spring-

POST compared to pyrasulfotole & bromoxynil treat-

ments, however fall-POST treatment was much better

than spring-POST treatment (88% - 95% vs 53% - 63%).

These results indicate that pyrasulfotole & bromoxynil

with or without tank mixtures controlled henbit better

than commercial standard triasulfuron & dicamba. How-

ever, fall applications of pyrasulfotole & bromoxynil

were better than spring applications. This could be due to

the fact that henbit was smaller in size in fall (1 - 2.5 cm)

compared to spring (2.5 - 7.5 cm). Contrary to our results,

Martin et al. (2008) [12] reported complete control of

henbit with pyrasulfotole & bromoxynil alone or in com-

bination with dicamba regardless of application timing

(fall or spring). In our experiment it was also noticed that,

in two instances, pyrasulfotole & bromoxynil + metsul-

furon-methyl applied spring-POST controlled henbit less

compared to pyrasulfotole & bromoxynil alone or in

combination with MCPA. Generally, ALS-inhibiting

herbicides (triasulfuron and metsulfuron-methyl) control

henbit better when applied in fall than spring.

3.1.2. Flixweed, Blue Mustard, Bushy Wallflower and

Field Pennycress

The premix of pyrasulfotole & bromoxynil alone or in

combination with MCPA, dicamba or metsulfuron-

methyl, across locations, controlled flixweed and blue

mustard, 98% or more regardless of application timing

(Table 4). Data on flixweed at Hays in 2008-2009 and at

Manhattan in 2007-2008 and 2009-2010, and on blue

mustard at Hays in 2007-2 08 are not presented here 0

Broadleaf Weed Control and Crop Safety with Premixed Pyrasulfotole and Bromoxynil in Winter Wheat

1616

Table 2. Analysis of variance (ANOVA) results for weed control and crop injurya,b.

Source HenbitFlixweed Blue mustardBushy wallflowerField pennycressWild buckwheat Injury-FInjury-S

Year *** ** * ** *** NS *** NS

Location *** NS - - - - *** ***

Year × location *** *** - - - - *** ***

Treatment *** *** *** *** *** *** ** ***

Year × treatment *** *** *** *** *** NS NS **

Location × treatment *** *** - - - - ** ***

Year × location × treatment *** *** - - - - ** NS

aAbbreviation: NS, not significant; injury-F, injury due to fall treatments; injury-S, injury due to spring treatments; bResults of ANOVA based upon arc-

sine-transformed data; *P = 0.05 - 0.01; **P = 0.01 - 0.001; ***P = 0.001 - 0.0001.

Table 3. Henbit control with POST application of premixed pyrasulfotole & bromoxynil and its tank mixtures, Hays and

Manhattan, KSa.

Hays Manhattan

Rate

2007-2008 2008-2009 2007-2008 2008-2009 2009-2010

Treatmentsb Time of

application

g·ha−1 ---------------------------------------------%---------------------------------------------

Pyrasulfotolec Fall 253 100 99 98 98 100

Pyrasulfotole + MCPA Fall 207 + 280 100 100 99 100 100

Pyrasulfotole + dicamba Fall 207 + 140 100 100 98 100 100

Pyrasulfotole + metsulfuron-methyl Fall 207 + 4.2 100 100 100 100 100

Triasulfuron & dicamba Fall 165 100 100 88 92 95

Pyrasulfotole Spring 253 94 100 99 80 97

Pyrasulfotole + MCPA Spring 207 + 280 95 99 99 82 100

Pyrasulfotole + dicamba Spring 207 + 140 93 99 92 72 100

Pyrasulfotole + metsulfuron-methyl Spring 207 + 4.2 86 100 93 67 97

Triasulfuron & dicamba Spring 165 84 100 63 53 53

LSD (0.05) 4 NS 4 10 5

aAbbreviations: NS, non-significant; bAll herbicide treatments include non-ionic surfactant at 0.5% v/v and 28% urea ammonium nitrate at 4.7 L·ha−1; cPyra-

sulfotole has bromoxynil as premix partner.

because weed control was almost complete and treatment

differences were not significant. These results are con-

sistent with reports of 98% - 99% control of flixweed and

96% - 99% control of blue mustard in Oregon with

spring-applied pyrasulfotole & bromoxynil [13]. In our

study, bushy wallflower and field pennycress were con-

trolled 90% or more, regardless of application time, and

there were no significant differences among treatments

(data not shown). The commercial standard triasulfuron

& dicamba controlled all four weeds completely when

applied fall-POST, but control was occasionally lower

than pyrasulfotole & bromoxynil treatments when ap-

plied in spring. Across locations, triasulfuron & dicamba

applied spring-POST controlled flixweed by 83% - 100%,

blue mustard 89% - 100%, bushy wallflower 90% -

100% and field pennycress 90% - 100%.

3.1.3. Wi ld Buckwh eat

At Manhattan, wild buckwheat emerged late after fall-

POST application and plants were small at the time of

spring-POST application. Spring-applied pyrasulfotole &

bromoxynil alone or in combination with MCPA pro-

vided poor wild buckwheat control (3% and 12%, re-

spectively) (Table 4). However, when pyrasulfotole &

bromoxynil was tank mixed with dicamba or metsulfu-

ronmethyl control of wild buckwheat was 84% or more.

Spring applied triasulfuron & dicamba controlled wild

buckwheat 94%. Even though wild buckwheat had not

emerged at the time of fall-POST application, pyrasul-

fotole & bromoxynil + metsulfuron-methyl and triasul-

furon & dicamba applied in fall controlled wild buck-

wheat 73% and 87%, respectively. This might be due to

residual activity of metsulfuron and triasulfuron in the

Broadleaf Weed Control and Crop Safety with Premixed Pyrasulfotole and Bromoxynil in Winter Wheat 1617

soil. Metsulfuron-methyl and triasulfuron can persist in

the soil up 4 and 12 weeks, respectively [14]. These re-

sults indicated that pyrasulfotole & bromoxynil premix

alone applied in spring has very little effect on wild

buckwheat.

3.2. Crop Injury and Grain Yields

At Hays, averaged over years, pyrasulfotole & bro-

moxynil alone or in combination with MCPA or dicamba

or metsulfuron-methyl applied in fall or spring caused 1

to 4% wheat injury, but the injury was not significant

among treatments (Table 5). At Manhattan, no injury

was obesrved with pyrasulfotole & bromoxynil treat-

ments when applied in fall, but up to 7% injury was ob-

served when applied in spring. Triasulfuron & dicamba

caused 0% to 6% injury. However, injury symptoms dis-

appeared within 3 to 4 weeks and did not influence wheat

grain yields (data not shown). In a study conducted at

Oregon, no wheat injury was observed with pyrasulfotole

& bromoxynil applied in spring at 282 g·ai·ha−1 [13].

This tolerance in wheat might be due to faster metabolic

degradation of the herbicide inside the plant. Wheat grain

Table 4. Fixweed, blue mustar d and wild buckwheat control with POST application of premixed pyrasulfotole & bromoxynil

and its tank mixtures.

Flixweed Blue mustard Wild buckwheat

Hays Manhattan Hays Manhattan

Rate

2007-2008 2008-2009 2007-2008 Pooledc&d

Treatmentsa Time of

application

g·ha−1 ------------------------------------------%------------------------------------------

Pyrasulfotoleb Fall 253 100 100 99 0

Pyrasulfotole + MCPA Fall 207 + 280 100 100 99 0

Pyrasulfotole + dicamba Fall 207 + 140 100 100 98 0

Pyrasulfotole + metsulfuron-methyl Fall 207 + 4.2 100 100 100 73

Triasulfuron & dicamba Fall 165 100 100 100 87

Pyrasulfotole Spring 253 100 100 99 3

Pyrasulfotole + MCPA Spring 207 + 280 100 100 100 12

Pyrasulfotole + dicamba Spring 207 + 140 100 100 100 84

Pyrasulfotole + metsulfuron-methyl Spring 207 + 4.2 100 100 100 92

Triasulfuron & dicamba Spring 165 96 83 89 94

LSD (0.05) 1 3 2 12

aAll herbicide treatments include non-ionic surfactant at 0.5% v/v and 28% urea ammonium nitrate at 4.7 L·ha−1; bPyrasulfotole has bromoxynil as premix

partner; cData pooled over years 2007-2008 and 2008-2009; dWild buckwheat did not emerge at the time of fall applications.

Table 5. Wheat injury caused by premixed pyrasulfotole & bromoxynil and its tank mixtures applied in fall and spring sea-

sons, Hays and Manhattan, KSa.

14 DAFT 14 DAST

Rate

Hays Manhattan Hays Manhattan

Treatmentsb

g·ha−1 ------------------------------------------------%------------------------------------------------

Pyrasulfotolec 253 2 0 2 0

Pyrasulfotole + MCPA 207 + 280 1 0 1 0

Pyrasulfotole + dicamba 207 + 140 4 0 1 7

Pyrasulfotole + metsulfuron-methyl 207 + 4.2 3 0 2 1

Triasulfuron & dicamba 165 4 0 0 6

LSD (0.05) NS NS NS 2

aAbbreviations: DAFT, days after fall treatments; DAST, days after spring treatments; NS, non-significant; bAll herbicide treatments include non-ionic surfac-

tant at 0.5% v/v and 28% urea ammonium nitrate at 4.7 L·ha−1. cPyrasulfotole has bromoxynil as premix partner.

Broadleaf Weed Control and Crop Safety with Premixed Pyrasulfotole and Bromoxynil in Winter Wheat

1618

yields were not influenced by any treatment compared to

untreated control (data not shown). High densities of

winter annual broadleaf species often reduce wheat yields,

sometimes dramatically, but controlling low to medium

density weed populations does not always result in higher

grain yields [15,16]. Analysis of 25 experiments con-

ducted over a several year period in Oklahoma found that

effective herbicidal control of weeds did not increase

wheat yields most of the time; yield increased when

bushy wallflower density was as much as 830 plants·m−2

[16]. Still good weed control is necessary in winter wheat

to prevent multiplication of weed density in future.

4. Conclusion

Premixed pyrasulfotole & bromoxynil alone at 253

g·ai·ha−1 or pyrasulfotole & bromoxynil at 207 g·ai·ha−1

in combination with MCPA, dicamba or metsulfuron-

methyl applied postemergence either in fall or spring

controlled blue mustard, flixweed, bushy wallflower and

field pennycress 98% or more. Henbit control with pyra-

sulfotole & bromoxynil treatments was much better when

they were applied in fall than spring (≥98% vs ≥67%).

Pyrasulfotole & bromoxynil applied alone in spring was

not effective on wild buckwheat, but tank mixing with

dicamba or metsulfuron-methyl controlled wild buck-

wheat 84% or more. Hence, tank mixing pyrasulfotole &

bromoxynil with other herbicides is desirable for broad

spectrum of weed control. Minor (≤7%) or no crop injury

was noticed with pyrasulfotole & bromoxynil treatments

regardless of application time. It can be concluded that

the new herbicide pyrasulfotole & bromoxynil can safely

be used in wheat for broadleaf weed control in spring or

fall season, but fall application is desirable for better

weed control. With a new and unique mode of action,

premix of pyrasulfotole & bromoxynil is an effective

alternative herbicide for wheat growers to combat weeds

resistant to ALS-inhibiting herbicides.

5. Acknowledgements

The authors thank Bayer CropScience for their financial

support to this project. Contribution number 13-174-J

from the Kansas Agricultural Experiment Station.

REFERENCES

[1] USDA-NASS (US Department of Agriculture-National

Agricultural Statistics Service), “Acreage-June 2012,”

USDA-NASS, Washington, 2012.

http://usda01.library.cornell.edu/usda/current/Acre/Acre-0

6-29-2012.pdf

[2] D. G. Swan, “Competition of Blue Mustard with Winter

Wheat,” Weed Scie nce, Vol. 19, No. 4, 1971, pp. 340-342.

[3] S. P. Conley and K. W. Bradley, “Wheat (Triticum aesti-

vum) Yield Response to Henbit (Lamium amplexicaule)

Interference and Simulated Winterkill,” Weed Technology,

Vol. 19, No. 4, 2005, pp. 902-906.

doi:10.1614/WT-04-252R.1

[4] F. E. Northam, P. W. Stahlman and M. Abd El-Hamid,

“Broadleaf weed Control in Winter Wheat,” Western So-

ciety of Weed Science Research Progress Report, Vol.

111, 1993, pp. 173-175.

[5] D. E. Peterson, “Weed Management,” Wheat Production

Handbook, Kansas State University Cooperative Exten-

sion Service, Manhattan, 1997, C-529.

[6] I. Heap, “The International Survey of Herbicide Resistant

Weeds,” 2012. www.weedscience.com.

[7] D. E. Peterson, K. Al-Khatib and R. Roberts, “ALS Re-

sistance in a Biotype of Bushy Wallflower,” Proceedings

of Western Society of Weed Science, Vol. 59, 2006, p. 42.

[8] D. E. Peterson, K. Al-Khatib, C. R. Thompson and T. M.

Maxwell, “Confirmation of ALS-Resistant Flixweed in

Kansas,” Proceedings of Western Society of Weed Science,

Vol. 62, 2009, p. 30.

[9] V. A. Andreas, “New HPPD-Inhibitors—A Proven Mode

of Action as a New Hope to Solve Current Weed Prob-

lems,” Outlooks on Pest Management, Vol. 20, No. 1,

2009, pp. 27-30. doi:10.1564/20feb09

[10] A. Trebst, B. Depka, J. Jager and W. Oettmeier, “Reversal

of the Inhibition of Photosynthesis by Herbicides Affect-

ing Hydroxyphenylpyruvate Dioxygenase by Plastoquin-

one and Tocopheryl Derivatives in Chlamydomonas rein-

hardii,” Pest Management Science, Vol. 60, 2004, pp.

669-674. doi:10.1002/ps.847

[11] A. Schulz, O. Oswald, P. Beyer and H. Kleinig, “SC-0051,

a 2-Benzoyl-cyclohexane-1,3-dione Bleaching Herbicide,

Is a Potent Inhibitor of the Enzyme p-Hydroxypheny-

lpyruvate Dioxygenase,” FEBS Letters, Vol. 318, 1993,

pp. 162-166. doi:10.1016/0014-5793(93)80013-K

[12] J. Martin, C. Tutt and D. Call, “Herbicide Evaluation of

Henbit Control in No-Till Wheat,” 2008.

http://www.ca.uky.edu/ukrec/RR%202007-08/RR07-08pg

40.pdf

[13] J. Felix and J. Ishida, “Huskie Herbicide Performance

Relative to Commercial Standard Herbicides in Winter

Wheat,” Malheur Experiment Station Annual Report 2008,

Oregon State University, Ontario, 2009, pp. 151-152.

http://ir.library.oregonstate.edu/xmlui/bitstream/handle/19

57/13358/MalheurExperimentStationAnnualReport2008.p

df?sequence=1

[14] C. R. Thompson, D. E. Peterson, W. H. Fick, P.W.

Stahlman and R. E. Wolf, “Chemical Weed Control for

Field Crops, Pastures, Rangeland, and Non-Cropland,”

Report of Progress 1063, Kansas State University, Man-

hattan, 2012.

[15] T. A. Baughman and T. F. Peeper, “Red Horn Poppy

(Glaucium corniculatum) Control in Winter Wheat,”

Weed Technology, Vol. 6, No. 4, 1992, pp. 909-912.

[16] R. C. Scott, T. F. Peeper and J. A. Koscelny, “Winter

Wheat (Triticum aestivum) Yield Response to Winter

Annual Broadleaf Weed Control,” Weed Technology, Vol.

9, No. 3, 1995, pp. 594-598.