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Crop Protection 30 (2011) 849e853

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Crop Protection

journal homepage: www.elsevier .com/locate/cropro

Response of spring planted barley (Hordeum vulgare L.), oats (Avena sativa L.)and wheat (Triticum aestivum L.) to mesotrione

Nader Soltani*, Christy Shropshire, Peter H. SikkemaUniversity of Guelph Ridgetown Campus, 120 Main Street East, Ridgetown, Ontario N0P 2C0, Canada

a r t i c l e i n f o

Article history:Received 22 September 2010Received in revised form17 March 2011Accepted 19 March 2011

Keywords:BarleyHeightHerbicide sensitivityOatsToleranceYieldWheat

* Corresponding author. Tel.: þ1 519 674 1645; fax:E-mail address: nsoltani@ridgetownc.uoguelph.ca

0261-2194/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.cropro.2011.03.023

a b s t r a c t

There is little information on the response of spring planted barley (Hordeum vulgare L.), oats (Avenasativa L.) and wheat (Triticum aestivum L.) to mesotrione under Ontario environmental conditions. Fourfield studies were conducted in Ontario, Canada over a two-year period (2008 and 2009) to evaluate thesensitivity of spring planted cereals (barley, oats, and wheat) to pre-emergence (PRE) and post-emer-gence (POST) applications of mesotrione at 50, 100, and 150 g ai ha�1. Mesotrione applied PRE causedminimal visible injury at 3, 7, 14 and 28 days after emergence (DAE) and had no adverse effect on plantheight or yield of barley, oats and wheat. Mesotrione applied POST caused as much 11% injury andreduced plant height as much as 6% in spring planted cereals. Injury was higher in wheat compared tobarley or oats. Mesotrione applied POST had no adverse effect on the yield of barley or oats but decreasedthe yield of wheat as much as 14%. Based on this study, mesotrione applied PRE at 50, 100 or 150 g ai ha�1

can be safely used in spring planted barley, oats, and wheat. Mesotrione applied POST at the proposeddose of 50, 100 or 150 g ai ha�1 can also be safely used in spring planted barley and oats. However,mesotrione applied POST results in unacceptable injury in spring planted wheat.

� 2011 Elsevier Ltd. All rights reserved.

1. Introduction

Cereals are an important crop in Ontario where they are used asfeed for livestock and as food for human consumption. There is anincrease in the global demand for cereals, especially wheat, and it iscrucial for Ontario growers to be able to respond to that marketneed. Recently, there has been renewed interest in spring cerealsdue to improved cultivars, reduced-till production systems,increased prices and the benefits derived from a diversified croprotation. One of the most significant aspects of spring cerealproduction is weedmanagement (Sikkema et al., 2008). Substantialcrop yield and associated economic losses can occur if weeds arenot adequately controlled. With the increased interest in reducedand no-till spring cereal production in Ontario, it would beadvantageous for producers if herbicides that provide residualbroadleaved weed control could be tank mixed with glyphosate.This would allow growers to combine two weed managementoperations. Efficacious and cost effective pre-emergence (PRE)applied residual broadleaved herbicides that do not result inunacceptable injury need to be developed to enable cereal growersto be more competitive in the marketplace.

þ1 519 674 1500.(N. Soltani).

All rights reserved.

Herbicides that are currently available in cereals in Ontario havenot changed much over the past two decades. Post-emergence(POST) herbicides such as 2,4-D, bromoxynil, dicamba, dichlorprop,MCPA, thifensulfuron-methyl and tribenuron-methyl are still beingused, either alone or in combination for the control of broadleavedweeds in cereals (Ivany et al, 1990; OMAFRA, 2010). There havebeen reports of crop sensitivity in cereals with some of theseherbicides (Sikkema et al., 2007). There are currently no soilapplied residual herbicides available for broadleaved weed controlin barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat(Triticum aestivum L.) in Ontario. To improve their competitiveposition, it would be advantageous for Ontario growers if newresidual herbicides that provide selective and consistent control ofannual broadleaved weeds were registered. More research isneeded to determine the tolerance of cereal crops to PRE appliedbroadleaved herbicides.

Mesotrione is a relatively new herbicide for maize in NorthAmerica that controls broadleaved weeds including Abutilon theo-phrasti Medic. (velvetleaf), Xanthium strumarium L. (commoncocklebur), Chenopodium album L. (common lambsquarters),Amaranthus retroflexus L. (redroot pigweed), Polygonum persicariaMill. (ladysthumb), and Ambrosia trifida L. (giant ragweed) andsome grass species including Digitaria sanguinalis (L.) Scop. (largecrabgrass) and Echinochloa crus-galli (L.) Beauv. (barnyardgrass)(Armel et al., 2003; O’Sullivan et al., 2002; Senseman, 2007).

Table 1Significance of main effects and interactions for percent injury, height and yield ofspring planted cereals treated with mesotrione. Means followed by the same letterwithin a column are not significantly different according to Fisher’s Protected LSD atP < 0.05. Means for a main effect were separated only if there was a significantinteraction involving that main effect.a

Main effectsb Spring cereal injury

7 DAE/DAA

3 DAT E1, 2, 4 E3% 14 DAT 28 DAT Heightcm

Yield(t ha�1)

Applicationtiming

NS * ** ** ** ** NS

Untreated 0 0 0 0 0 93 4.0Pre-emergence 0 0 0 0 0 92 4.0Post-emergence 3 5 10 6 4 90 3.9SE 0.4 0.3 1.4 0.5 0.4 0.5 0.1Type of spring

cerealNS * ** ** ** ** **

Barley 1 1 1 0 1 85 4.3Oats 1 1 2 1 0 101 4.9Wheat 2 3 9 6 4 86 2.7SE 0.4 0.3 1.4 0.5 0.4 0.5 0.1Mesotrione

dosec

(g ai ha�1)

* ** ** ** ** ** NS

0 0 0 0 0 0 93 4.050 1 1 2 1 1 91 4.0100 1 2 4 2 2 90 3.9150 2 3 5 3 2 89 3.9SE 0.4 0.3 1.4 0.5 0.4 0.5 0.1InteractionsT � C NS * ** ** ** ** **

T � D * ** ** ** ** ** **

C � D NS NS ** * ** ** *

T � D � C NS NS ** * ** ** NS

a Abbreviations: DAE/DAA, days after emergence/application; E1, Exeter 2008a;E2, Exeter 2008b; E3, Exeter 2009a; E4, Exeter 2009b; T, application timing; C, typeof spring cereal; D, mesotrione dose; NS, not significant at P ¼ 0.05 level.

b Significance at P < 0.05 and P < 0.01 levels denoted by * and **, respectively.c Post-emergence treatments included non-ionic surfactant at 0.2% v/v.

Table 2Percent injury and yield of spring planted cereals at two application timings asa function of mesotrione dose. Means followed by the same letter within a column(aec) or row (YeZ) for each section are not significantly different according toFisher’s protected LSD at P < 0.05.a

Mesotrione dose (g ai ha�1)by Variable

Application timingb

Pre-emergence % Post-emergence % SE

Injury 3 DAE/DAA0 0 a Z 0 a Z 050 0 a Z 1 a Y 0.4100 0 a Z 3 b Y 0.8150 0 a Z 5 b Y 0.9SE 0 0.8

Injury 7 DAE/DAA (E1, E2, E4)0 0 a Z 0 a Z 050 0 a Z 2 a Y 0.3100 0 a Z 6 b Y 0.6150 0 a Z 8 c Y 0.7SE 0 0.5

Injury 7 DAE/DAA (E3)0 0 a Z 0 a Z 050 0 a Z 3 a Y 1.5100 0 a Z 7 b Y 2.4150 0 a Z 10 c Y 3.2SE 0 2.4

Injury 14 DAE/DAA0 0 a Z 0 a Z 050 0 a Z 2 a Y 0.4100 0 a Z 6 b Y 0.8150 0 a Z 11 c Y 1.2SE 0 0.9

Injury 28 DAE/DAA0 0 a Z 0 a Z 050 0 a Z 1 a Y 0.2100 0 a Z 4 b Y 0.6150 0 a Z 7 c Y 0.8SE 0 0.6

Height (cm)0 93 a Z 93 a Z 1.050 92 a Z 91 a Z 1.0100 92 a Z 89 b Y 1.0150 92 a Z 87 b Y 1.2SE 0.7 0.8

Yield (t ha�1)0 4.0 a Z 4.0 a Z 0.150 4.1 a Z 4.0 a Z 0.2100 4.0 a Z 3.9 ab Z 0.2150 4.1 a Z 3.7 b Y 0.2SE 0.1 0.1

a Abbreviations: DAE/DAA, days after emergence/application; E1, Exeter 2008a;E2, Exeter 2008b; E3, Exeter 2009a; E4, Exeter 2009b.

b Post-emergence treatments included non-ionic surfactant at 0.2% v/v.

N. Soltani et al. / Crop Protection 30 (2011) 849e853850

Mesotrione is a triketone that inhibits the p-hydroxyphenylpyr-uvate dioxygenase (HPPD) enzyme responsible for catalyzing theconversion of tyrosine to plastoquinone and a-tycopherol(Abendroth et al., 2006; Hess, 2000; Mitchell et al., 2001). Meso-trione can be absorbed by the dry seed, emerging root, and shootand is translocated in the xylem and phloem (Senseman, 2007).Injury symptoms with mesotrione in susceptible plants includebleaching of meristemic tissue followed by growth cessation andnecrosis within 3e5 days (Abendroth et al., 2006; Senseman, 2007).Mesotrione has a favorable environmental and toxicological profilewith relatively low toxicity to mammals, birds and aquatic species(O’Sullivan et al., 2002).

There is limited information published on the tolerance ofspring planted barley, oats, and wheat to mesotrione under Ontarioenvironmental conditions. Mesotrione, at relatively low use dosescan provide growers with an additional herbicide mode-of-actionto provide season-long control of broadleaved weeds includingacetolactate synthase and triazine-resistant biotypes in springplanted barley, oats, and wheat.

The objective of this researchwas to evaluate tolerance of springplanted cereals (barley, oats, and wheat) to pre-emergence (PRE)and post-emergence (POST) applications of mesotrione at 50, 100,and 150 g ai ha�1.

2. Materials and methods

Four field studies were conducted at the Huron ResearchStation, Exeter, Ontario over a two-year period (E1, Exeter 2008a;E2, Exeter 2008b; E3, Exeter 2009a; E4, Exeter 2009b). The soils for

the study sites were a Brookston clay loam with 38% sand, 41% silt,21% clay, 3.7% OM, and pH of 7.8 in 2008 (E1 and E2), and 39% sand,33% silt, 28% clay, 4.7% OM, and pH of 7.9 in 2009 (E3 and E4).Seedbed preparation consisted of moldboard plowing in theautumn followed by two passes with a cultivator with rollingbasket harrows in the spring.

Experiments were arranged in a randomized complete blockdesign in a three-way factorial arrangement with four replications.Factor 1 was the type of cereal (barley, oats, or wheat), factor 2was dose of mesotrione (0, 50, 100, or 150 g ai ha�1) and factor 3was application timing [pre-emergence (PRE) or post-emergence(POST)]. Post-emergence treatments included non-ionic surfactantat 0.2% v/v. Plots were 2mwide by 10m long. Spring barley culitivar‘Bornholm’, oats ‘Sherwood’, and wheat ‘Hobson’were seeded witha double disc drill at 130 kg ha�1 in rows 17.5 cm apart at a depth of4 cm on April 17 and 21, 2008 and April 16 and 25, 2009 at site 1 and2, respectively.

The PRE applications of meostrione were applied within 3 daysafter seeding and the POST applications was applied at Zadoks

Table 3Percent visual injury and yield for three types of spring planted cereals as a functionof mesotrione application timing. Means followed by the same letter withina column (aec) or row (YeZ) for each section are not significantly differentaccording to Fisher’s Protected LSD at P < 0.05.a

Type of spring cerealby variable

Application timingb

Untreated Pre-emergence Post-emergence SE

Injury 7 DAE/DAA (E1, E2, E4) %Barley 0 a Z 0 a Z 3 a Y 0.4Oats 0 a Z 0 a Z 3 a Y 0.3Wheat 0 a Z 0 a Z 9 b Y 0.8SE 0 0 0.5

Injury 7 DAE/DAA (E3)Barley 0 a Z 0 a Z 3 a Y 0.5Oats 0 a Z 0 a Z 4 a Y 0.5Wheat 0 a Z 0 a Z 13 b Y 3.6SE 0 0 2.4

Injury 14 DAE/DAABarley 0 a Z 0 a Z 2 a Y 0.3Oats 0 a Z 0 a Z 2 a Y 0.2Wheat 0 a Z 0 a Z 20 b Y 1.3SE 0 0 0.9

Injury 28 DAE/DAABarley 0 a Z 0 a Z 2 b Y 0.2Oats 0 a Z 0 a Z 1 a Z 0.1Wheat 0 a Z 0 a Z 12 c Y 0.9SE 0 0 0.6

Height (cm)Barley 86 Z 86 Z 85 Z 0.5Oats 101 Z 101 Z 101 Z 0.6Wheat 90 Z 89 Z 83 Y 0.8

Yield (t ha�1)Barley 4.4 Z 4.4 Z 4.3 Z 0.1Oats 4.8 Z 4.9 Z 4.8 Z 0.1Wheat 2.9 Z 2.9 Z 2.5 Y 0.1

a Abbreviations: DAE/DAA, days after emergence/application; E1, Exeter 2008a;E2, Exeter 2008b; E3, Exeter 2009a; E4, Exeter 2009b.

b Post-emergence treatments included non-ionic surfactant at 0.2% v/v.

Table 4Percent visual injury, height and yield for three types of spring planted cereals asa function of mesotrione dose. Means followed by the same letter within a column(aed) or row (XeZ) for each section are not significantly different according toFisher’s Protected LSD at P < 0.05.a

Mesotrione dose (g ai/ha) Type of spring cereal

Barley Oats Wheat SE

Injury 7 DAE/DAA (E3) %0 0 a Z 0 a Z 0 a Z 050 0 a Z 1 a Z 3 b Y 1.5100 2 b Z 2 b Z 5 c Y 2.4150 2 b Z 2 b Z 6 c Y 3.2SE 0.5 0.5 3.6

Injury 14 DAE/DAA0 0 a Z 0 a Z 0 a Z 050 0 a Z 0 a Z 3 b Y 0.4100 0 a Z 1 b Z 6 c Y 0.8150 1 b Z 1 b Z 9 d Y 1.2SE 0.3 0.2 1.3

Injury 28 DAE/DAA0 0 a Z 0 a Z 0 a Z 050 0 a Z 0 a Z 2 b Y 0.2100 1 b Y 0 a Z 5 c X 0.6150 2 c Y 0 a Z 6 d X 0.8SE 0.2 0.1 0.9

Height (cm)0 86 a 101 a 90 a 1.050 86 a 101 a 87 b 1.0100 85 a 101 a 85 b 1.0150 84 a 101 a 82 c 1.2SE 0.5 0.6 0.8

Yield (t ha�1)0 4.4 a 4.8 a 2.9 a 0.150 4.3 a 5.0 a 2.8 ab 0.2100 4.4 a 4.8 a 2.6 bc 0.2150 4.3 a 4.9 a 2.5 c 0.2SE 0.1 0.1 0.1

a Abbreviations: DAE/DAA, days after emergence/application; E3, Exeter 2009a.

N. Soltani et al. / Crop Protection 30 (2011) 849e853 851

stage 18e22. Treatments were applied with a CO2 pressurizedbackpack sprayer calibrated to deliver 200 L ha�1 at 241 kPa. Theboom was 1.5 m long with four ULD 120-02 nozzles (SprayingSystems Co., Wheaton, IL, USA) spaced 50 cm apart. All plotsincluding the non-treated control were kept weed-free by handweeding.

Visible crop injury was rated on a scale of 0e100% (0¼ no visibleinjury, and 100¼ plant death) at approximately 3, 7, 14, and 28 daysafter emergence (DAE) for the PRE applications and 3, 7, 14, and 28days after application (DAA) for the POST applications. Ten plantswere randomly selected per plot and the height from the soilsurface to the highest growing point of each plant was measured at35 DAA. Cereals were harvested during the month of July atmaturity using a plot combine and yields were adjusted to 13.5,14.5and 14.8% moisture for oats, wheat and barley, respectively.

All data were subjected to analysis of variance. Tests werecombined over planting dates and years and analyzed using theMIXED procedure of SAS (1999). Variances were partitioned intothe random effects of planting dates, years, planting dates byyears, blocks within years by planting dates, and the interactionswith fixed effects (herbicide treatment and cereal type). Signifi-cance of random effects were tested using a Z-test of the varianceestimate and fixed effects were tested using F-tests. Errorassumptions of the variance analyses (random, homogeneous,normal distribution of error) were confirmed using residual plotsand the ShapiroeWilk normality test. To meet assumptions ofnormality, all injury data were square-root transformed except the14 DAE/DAA, which was arcsine square-root transformed (Bartlett,1947). Means were converted back to the original scale forpresentation of results. Means were Separated using Fisher’s pro-tected LSD at P < 0.05.

3. Results and discussion

Environment by cereal type by timing by dose interaction werenot significant for most variables, therefore the four datasets wereanalyzed together. Only injury 7 DAE/DAA had to be divided (due toa significant environment by cereal type by application timing bydose interaction). Exeter 2009a (E3) was analyzed separately fromthe other three environments. Application timing (PRE vs POST)was significant for injury 7, 14 and 28 DAE/DAA and height. Dosewas significant for injury 3, 7, 14 and 28 DAE/DAA and height, andcereal type was significant for injury 7, 14 and 28 DAE/DAA, heightand yield.

3.1. Injury

Injury symptoms included whitening/bleaching of the foliagefollowed by chlorosis of the leaf tissue and plant height reduction.There was no injury in barley, oats and wheat when mesotrionewas applied PRE at 3, 7, 14 and 28 DAE (Tables 1 and 2). The absenceof injury observed with the PRE application of mesotrione in thisstudy was similar to the level of injury found with many currentlyused POST herbicides in Ontario such as 2,4-D, MCPA, dichlorpropplus 2,4-D, and bromoxynil plus MCPA (OMAFRA, 2010; Sikkemaet al., 2007; Soltani et al., 2006).

Mesotrione applied POST caused as much as 5, 10, 11 and 7%injury in spring cereals at 3, 7, 14 and 28 DAA, respectively (Table 2).Injury remained relatively constant over time (3e28 DAA). Gener-ally, there was greater injury as the dose increased (Table 2). Injurywas greater in spring wheat than in spring barley or spring oats(Tables 3e5). Other studies have reported similar crop injury withPOST herbicides such as dicamba plus MCPA plus mecoprop in

Table 5Percent injury and height for three spring planted cereals as a function of mesotrione dose and application timing. Means followed by the same letter within a column (aed) orrow (XeZ) for each section are not significantly different according to Fisher’s Protected LSD at P < 0.05.a

Mesotrione dose (g ai ha�1) by variable Barley Oats Wheat

PRE POSTb PRE POST PRE POST SE

Injury 7 DAE/DAA (E3) %0 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 050 0 a Z 0 a Z 0 a Z 3 b Y 0 a Z 20 b X 1.5100 0 a Z 5 b Y 0 a Z 5 c Y 0 a Z 32 c X 2.4150 0 a Z 5 b Y 0 a Z 6 c Y 0 a Z 42 d X 3.2SE 0 0.8 0 0.5 0 3.0

Injury 14 DAE/DAA0 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 050 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 11 b Y 0.4100 0 a Z 1 b Y 0 a Z 2 b Y 0 a Z 22 c X 0.8150 0 a Z 5 c Y 0 a Z 5 c Y 0 a Z 31 d X 1.2SE 0 0.4 0 0.4 0 1.4

Injury 28 DAE/DAA0 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 050 0 a Z 0 a Z 0 a Z 0 a Z 0 a Z 5 b Y 0.2100 0 a Z 3 b Y 0 a Z 1 a Z 0 a Z 14 c X 0.6150 0 a Z 5 c Y 0 a Z 1 a Z 0 a Z 19 d X 0.8SE 0 0.4 0 0.2 0 1.2

Height (cm)0 86 a 86 a 101 a 101 a 90 a 90 a 1.050 86 a 86 a 100 a 101 a 88 a 85 b 1.0100 86 a 84 a 100 a 101 a 90 a 81 c 1.0150 85 a 84 a 101 a 101 a 89 a 76 d 1.2SE 0.7 0.8 0.9 0.9 0.9 1.2

a Abbreviations: DAE/DAA, days after emergence/application; E3, Exeter 2009a.b Post-emergence treatments included non-ionic surfactant at 0.2% v/v.

N. Soltani et al. / Crop Protection 30 (2011) 849e853852

winter wheat (Sikkema et al., 2007). Tottman (1977) foundunderdeveloped seeds with POST application of dicamba plusMCPA plus mecoprop. Schroeder and Banks (1989) also foundwinter wheat injury with early applications of dicamba or dicambaplus 2,4-D.

3.2. Height

There was no adverse effect on the height of spring plantedbarley, oats and wheat when mesotrione was applied PRE at 50,100, and 150 g ha�1 (Table 2). These results are similar to thosefound with currently used POST herbicides in Ontario such as 2,4-Damine, bromoxynil plus MCPA, and dichlorprop plus 2,4-D(OMAFRA, 2010; Sikkema et al., 2007, 2008).

Mesotrione applied POST reduced plant height by as much as6.5% (Table 2). Height of spring wheat was reduced while there wasno decrease in the height of spring barley and spring oats(Tables 3e5). Height of spring wheat decreased as the dose ofmesotrione was increased (Tables 4 and 5). Height reductions inspring wheat with mesotrione POST are similar with that reportedin other studies that have shown plant height reductions of up to16% in some cereals with POST herbicides such as dicamba,dicamba plus MCPA plus mecoprop, dicamba plus 2,4-D amine,dicamba plus MCPA and saflufenacil (Martin et al., 1989; Quimbyand Nalewaja, 1966; Sikkema et al., 2007, 2008).

3.3. Yield

There was no adverse effect on yield of barley, oats, and wheatcompared to the untreated check when mesotrione was appliedPRE at 50, 100, and 150 g ha�1 (Table 2). This is similar to the yieldresponse of cereals with herbicides such as saflufenacil, 2,4-Damine, bromoxynil plus MCPA, and dichlorprop plus 2,4-D(Sikkema et al., 2007, 2008).

Mesotrione applied POST had no adverse effect on yield ofspring barley or spring oats but caused a decrease in the yield of

spring wheat of up to 14% (Table 3). Generally, the yield of springwheat was reduced as the dose of meotrione was increased(Table 4). In other studies, cereal yields were reduced 12e39% withdicamba applied post alone, or in combination with a phenoxyherbicide (Martin et al., 1989). Other researchers have also reportedcereal yield losses with dicamba applied POST (Ivany et al., 1990;Rinella et al., 2001; Tottman, 1982). Tottman (1978) also foundthat tank-mixes containing dicamba, 2,3,6-TBA, MCPA or mecopropapplied POST to winter wheat can reduce grain yield. In anotherstudy, saflufenacil applied POST reduced yield of spring barley andwheat 24 and 13%, respectively but had no effect on the yield ofspring oats (Sikkema et al., 2008).

4. Conclusions

Based on this study, mesotrione applied PRE at the dose of 50,100 or 150 g ai ha�1 can be safely used in spring planted barley,oats, and wheat. Mesotrione applied POST at the dose of 50, 100 or150 g ai ha�1 can also be safely used in spring planted barley andoats. However, mesotrione applied POST results in unacceptableinjury in spring planted wheat at the doses evaluated in this study.

Acknowledgements

The authors acknowledge Todd Cowan for his expertise andtechnical assistance in these studies. Funding for this project wasprovided in part by the Grain Farmers of Ontario and AgriculturalAdaptation Council.

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