Ontario maize and soybean growers have numerous herbicide options  for managing weeds during the crit- ical weed-free period. Unfortunately, growers can sometimes miss registered herbicide application windows due to adverse weather conditions or mechanical breakdowns which leave large, highly competitive weeds present in the crop at a point beyond the critical weed-free period when rapid yield loss occurs -. At this time, grow- ers would like to apply a high dose of postemergence (POST) herbicide to ensure effective control of these large weeds, but growers also are concerned that crop injury could negatively impact yield. Regrettably, the tolerance of maize and soybean to a high herbicide dose at a late POST application timing is largely unknown. The excep- tion to this is maize, which can tolerate over two-fold of the maximum labeled dose of glyphosate applied at the 10-leaf stage with minimal injury and little to no yield loss . Furthermore, to the best of our knowledge, few studies have been conducted in the absence of confounding weed competition effects that examine both a range of herbicides comparing relative crop tolerance  and the tolerance of crops to a late POST herbicide applica- tion . Therefore, the objective of this research was to determine the tolerance of maize and soybean to a late application of select POST herbicides in the absence of weed interference.
There are a limited number of herbicide options available for durum wheat production in Ontario, Canada. Four field studies were conducted in Ontario, Canada over a three year period (2008, 2009 and 2010) to evaluate the sensitivity of spring planted durum wheat to post-emergence (POST) applications of dichlorprop/2,4-D, dicamba/ MCPA/mecoprop, clopyralid, bromoxynil/MCPA, pyrasulfotole/bromoxynil, thifensulfuron/tribe- nuron + MCPA amine, fluroxypyr + MCPA ester, tralkoxydim and fenoxaprop-p-ethyl/safener at the manufacturers’ recommended dose and twice that dose. Visible injury in durum wheat were 0 to 2.4% with dichlorprop/2,4-D, 0 to 6% with dicamba/MCPA/mecoprop, 0 to 0.4% injury with clopyralid, 0 to 1.4% injury with bromoxynil/MCPA, 0 to 3.5% with pyrasulfotole/bromoxynil, 0 to 5% with thifensulfuron/tribenuron + MCPA amine, 0 to 2.6% with fluroxypyr + MCPA ester, 0 to 5% with tralkoxydim and 0.4% to 8% with fenoxaprop-p- ethyl/safener at various evaluation dates (1, 2, 3 and 4 weeks after treatment). Durum wheat height was decreased as much as 5% with dicamba/ MCPA/mecoprop, 4% with pyrasulfotole/bromoxy- nil and 6% with fenoxaprop-pethyl/safener but was not affected with other herbicides evaluated. There was no decrease in durum wheat yield with the herbicides evaluated.
The experiments were arranged in a randomized com- plete block design with three to four replications. Dose response treatments included glyphosate applied at 112.5, 225, 450, 900, 1800, 2700, 5400, 10,800, 21,600 or 43,200 g·a.e.·ha –1 . Herbicides included in the POST herbicides experiment were glyphosate (900 g·a.e.·ha –1 ) applied alone, and chlorimuron-ethyl (9 g·a.i.·ha –1 + non-ionic surfac- tant at 0.2% vol/vol + 28% UAN at 2 L·ha –1 ), cloransu- lam-methyl (17.5 g·a.i.·ha –1 + non-ionic surfactant at 0.25% vol/vol + 28% UAN at 2.5% vol/vol), fomesafen (240 g·a.i.·ha –1 + crop oil concentrate at 0.5% vol/vol), imazethapyr (100 g·a.i.·ha –1 + non-ionic surfactant at 0.25% vol/vol + 28% UAN at 2.0 L·ha –1 ), or imazethapyr plus bentazon (75 and 840 g·a.i.·ha –1 + 28% UAN at 2.0 L·ha –1 ) applied alone and in a tank mix with glyphosate (900 g·a.e.·ha –1 ). The herbicide rates used in the POST experiment are the highest rate registered for use in On- tario. Each experiment included a weedy and weed-free check. All weed-free checks were maintained with gly- phosate (900 g·a.e.·ha –1 ) plus 2, 4-D ester (500 g·a.e.·ha –1 ) applied PP followed by hand hoeing as required.
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According to the developers, Crop Booster compensates for plant’s inability for nutrient uptake under stress from the soil by increasing foliar tissue nutrient concentration which enables plants to produce the enzymes and organic acid needed to combat stress . Crop Booster is also promoted by the Axter Agrosciences Inc. as a biostimulant that works synergistically with herbicides to decrease stresses that may be caused by the use of post emergence herbicides in crops .
There are several registered postemergence (POST) herbicides that can control common ragweed including glyphosate, 2,4-D ester, atrazine, dicamba, dicam- ba/diflufenzopyr, dicamba/atrazine, bromoxynil + atrazine, prosulfuron + dicamba, mesotrione + atrazine, topramezone + atrazine, tembotrione/thiencarbazone-methyl, glufosinate, and halosulfuron. However, there is little information on the efficacy of these herbicides to control GR common ragweed in GR corn under Ontario environmental conditions. This information is critical for corn growers to maximize control, minimize weed competition, and maximize corn yield and profitability as well as reducing loading of ineffective herbicides into the envi- ronment.
bromoxynil/thiencarbazone + MCPA ester, tolpyralate and flurox- ypyr/halauxifen + MCPA EHE, applied POST, provide inadequate control of common chickweed in winter wheat. Fluroxypyr/halauxifen + pyroxsulam + MCPA EHE, applied POST, provides good control of common chickweed in winter wheat. Herbicides that included tribenuron including thifensulfu- ron/tribenuron, thifensulfuron/tribenuron + MCPA ester, thifensulfu- ron/tribenuron + fluroxypyr + MCPA ester, tribenuron + thiencarbazone, and tribenuron + thiencarbazone + MCPA ester, applied POST, provide excellent control of common chickweed in winter wheat. However, common chickweed biotypes that are resistant to Group 2 herbicides including tribenuron have been found in many parts of North America  , but there is no report of the existence of these resistant biotypes in Ontario. However, the potential spread of these biotypes into Ontario will limit herbicide options for the control of Group 2-resistant common chickweed. Future research should focus on crop rotation and other weed control strategies including herbicide mixtures with multiple sites of action for common chickweed control in winter wheat under Ontario environmental conditions.
The effect of biostimulants such as Crop Booster and RR SoyBooster on dry bean under Ontario environmental conditions is not known. A total of 12 field experiments (6 in cranberry bean “Etna” and 6 in white bean “OAC REX”) were conducted at two locations (Ridgetown and Exeter, Ontario, Canada) to evaluate the effect of Crop Booster and RR SoyBooster on visible injury, shoot dry weight, height and yield of cranberry and white bean. Visible injury ranged from 0% to 7.3% in white bean and 0% to 9.4% in cranberry bean with quizalofop-p-ethyl, bentazon, fomesafen, ben- tazon plus fomesafen, imazethapyr and imazethapyr plus bentazon alone or in combination with Crop Booster and RR SoyBooster. The addition of Crop Booster or RR SoyBooster to herbicides evaluated had no significant effect on shoot dry weight, height, seed moisture content and yield of white or cranberry bean except with the addition of RR SoyBooster to quizalofop-p-ethyl which increased height 3.7% and the addition of the Crop Booster to bentazon which decreased shoot dry weight 12% and the addition of Crop Booster to bentazon plus fomesafen which increased shoot dry weight 17% in white bean. Based on these results, there were minimal effects from the addition of Crop Booster or RR SoyBooster to commonly used herbicides in white and cranberry bean.
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Cotton growers rely heavily upon herbicides for weed control. A typical herbicide program for cotton in the Southeast begins with application of two or more herbicides at planting. Most fields also require postemergence herbicides for adequate weed control. Several herbicides can be applied postemergence over the top of cotton for annual and perennial grass control without injury to the crop. Postemergence control of broadleaf weeds has typically been achieved with directed herbicide applications. For effective weed control and adequate crop safety with postemergence-directed herbicides, a height differential between the crop and weeds is required. This height differential is often difficult to achieve as cotton usually grows more slowly early in the season than broadleaf weeds. Additionally, directed application of herbicides to small cotton is a slow and tedious operation requiring special equipment and precise operation. Growers prefer to apply herbicides over the top of cotton. Fluometuron (Cotoran, Meturon, and others) and the organic arsenicals MSMA and DSMA can be applied overtop but weed scientists caution that these herbicides applied in this manner can delay cotton maturity and reduce yield.
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Silverleaf nightshade is a deep-rooted summer perennial weed of southern Australia. Chemical and physical control tactics used for the past half century have not always been successful due to the resilience of the root system. Multi-year experiments established near Culcairn, NSW and Leeton, NSW showed that herbicides can reduce annual stem regrowth by up to 90%, depending upon the herbicide used and the time of application. Herbicide treatments containing the active ingredient picloram were the most effective, particularly if applied annually in summer and autumn. Competition from the perennial sub-tropical pasture species finger grass and digit grass at a field site at Wellington, NSW provided 94% suppression of silverleaf nightshade after two seasons.
None of the tested adjuvants significantly affected sunflower injury by any tested herbicide (Table 3). Sunflower injury was significantly higher in 2012, when higher precipitation was recorded during April (Table 1) and the herbicide was transported to young roots of the emerging sunflower. Also, temperature can affect the selectivity of some herbicides. Harrison and Peterson (1999) showed that broccoli (Brassica oleracea) was less sensitive to oxyfluorfen at temperatures between 20°C and 25°C, compared to temperatures from 10°C to 15°C. Efficacy. The efficacy of flurochloridone and linuron on F. convolvulus was strongly affected by weather conditions during April of each year. The efficacy of these two herbicides was higher in 2012 (95–99%), when the total natural precipita-
The aim of this work was to compare herbicide efficacy and reduction of weed reproduction after the application of three frequently used soil residual herbicides during pre-emergent (PRE) and early post-emergent (EPOST) application in maize. Plot field trials were carried out in Central Bohemia during two growing seasons (2010 and 2011). Good efficacy (88%, resp. 83%) was found in isoxaflutole + thiencarbazone (ISF + THC) and terbuthylazin + S-metolachlor (TBA + SMC) on Echinochloa crus-galli, especially in PRE application use. Efficacy on Amaran- thus retroflexus was 91% at both tested application periods and there were no significant differences between ex- perimental years. Significant differences in A. retroflexus control were recorded among all tested herbicides (ISF + THC > TBA + SMC > pendimethalin (PEM) + dimethenamid (DMA)). No significant differences between PRE and EPOST were recorded in efficacy on Chenopodium album. Significant differences in efficacy on C. album were recorded among all tested herbicides (ISF + THC > TBA + SMC > PEM + DMA). Mercurialis annua was the most tolerant tested weed, which was significantly better controlled at EPOST herbicide application (73%) compared to PRE application (32%). TBA + SMC showed a significantly higher efficacy on M. annua compared with other tested herbicides. Seed production of all tested weeds was strongly effected by weather conditions, which were significant during 2011, when there was higher than average precipitation during May and June. The most seeds were pro- duced by A. retroflexus > C. album > E. crus-galli > M. annua. ISF + THC best reduced seed production of E. crus- galli, A. retroflexus and C. album, especially when applied at PRE. TBA + SMC best reduced seed production of M. annua. Weed competition on untreated control plots caused yield loss by 90%and 47% in 2011 and 2012, respec- tively, compared to treatments with the highest yield (ISF + THC).
There are a limited number of postemergence (POST) herbicides available for weed manage- ment in mung bean production in Ontario. Five field studies were conducted in 2010, 2011 and 2012 near Exeter, Ontario and in 2011 and 2012 near Ridgetown, Ontario to determine the toler- ance of mung bean to fomesafen, bentazon, ben- tazon + fomesafen and halosulfuron applied POST at the 1X and 2X proposed manufacturer’s recommended rate. Bentazon caused 5% - 29%, 4% - 31%, and 2% - 18% injury, fomesafen caus- ed 3% - 17%, 1% - 7%, and 0% - 6% injury, ben- tazon + fomesafen caused 6% - 40%, 4% - 37%, and 1% - 20% injury, and halosulfuron caused 13% - 65%, 8% - 75%, and 5% - 47% injury in mung bean at 1, 2, and 4 weeks after treatment (WAT), respectively. At Exeter, fomesafen had no adverse effect on height of mung bean but ben- tazon, bentazon + fomesafen and halosulfuron decreased mung bean height as much as 5% compared to the untreated control. At Ridge- town, there was no decrease in mung bean height due to the herbicides applied. Fomesafen had no adverse effect on shoot dry weight of mung bean but bentazon, bentazon + fomesafen and halo- sulfuron decreased shoot dry weight of mung beans as much as 43%, 47%, and 57%, respec- tively. Fomesafen, bentazon, bentazon + fomesa- fen and halosulfuron had no adverse effect on the seed moisture content and seed yield of mung bean with the exception of halosulfuron applied POST at 70 g ai ha −1 which increased seed moi- sture content 0.4% at Exeter and 1.4% at Ridge- town and decreased yield 16% at Exeter compar- ed to the untreated control. Based on these re- sults, there is not an adequate margin of crop safety for bentazon, bentazon + fomesafen and
check plots. Other herbicides like Agritop, Isoproturon and 2,4-D having the values (175.2, 173.1 and 170.9) were intermediate in tillers production. The grasses escaped from their phytotoxicity and were competitive with wheat resulting in lesser tillers. Among the seed rates the highest number of tillers (194.95) m -2 were recorded in 160
In India, agriculture is an important component of economy and majority of population is dependent on agricultural earnings. There is much loss of agricultural products due to presence of weeds in the farms. There is geographical and biological diversity of weeds which require much use of different types of herbicides [8, 9]. In the present study, we studied structural similarity and substrate affinity of starch phosphorylase using in silico approach. Besides, we also studied the influence of herbicides on this enzyme. To the best our knowledge, it is the first report on the influence of herbicides on starch phosphorylase.
that medium-intensive technology (60 kg N/ha and two herbicides) as compared to the extensive technology (40 kg/ha and without herbicides) had no significant effect on seed yield and plant density of both linseed cultivars, however, the increase of these traits was significant only in the intensive cultivation technology (80 kg N/ha and three her- bicides). From the analysis of variance over three years of the experiment, it was found that only seed yield and capsules per plant were significantly influenced by interaction between row spacing and agrotechnical level, while interactions between Table 1. The effect of cultivar, row spacing and agrotechnical level on seed yield and some morphological fea- tures of linseed
Glufosinate controls a broad spectrum of weeds in glufosinate-resistant cotton (Gossypium hirsutum L.). Control of grassy weeds, however, can sometimes be inadequate, especially when grasses are large or growing under dry conditions. In situations where less than adequate control of grasses by glufosinate alone is anticipated, growers may consider mixing a postemergence graminicide with glufosinate. Most herbicides mixed with graminicides antagonize grass con- trol. Research was conducted in North Carolina to determine the potential for antagonism with mixtures of glufosinate and four postemergence graminicides and to determine if antagonism could be alleviated by increasing the rate of graminicide in mixtures, by adding ammonium sulfate to mixtures, or by applying glufosinate and graminicides sequentially. Antagonism was noted on johnsongrass [Sorghum halepense (L.) Pers.] and on mixtures of annual grasses, broadleaf sig- nalgrass [Brachiaria platyphylla (Griseb.) Nash], fall panicum (Panicum dichotomiflorum Michx.), goosegrass [Eleusine indica (L.) Gaertn.], and large crabgrass [Digitaria sanguinalis (L.) Scop.], when glufosinate was mixed with clethodim, fluazifop-P, quizalofop-P, or sethoxydim. Antago- nism was not alleviated by increasing the gramini- cide rate in the mixture by 50% or by including ammonium sulfate in the mixture. Antagonism was not observed when graminicides were applied 3 or more days before glufosinate or 5 or more days after glufosinate.
ed from the control object (Table 3), however, these differences were not statistically signifi- cant. These results were confirmed in the previ- ous studies of Zarzecka, Gugała , who demonstrated that the herbicides used in the care impacted the reduction of the phosphorus content compared to the tubers from the control object. While Wichrowska et al.  found that the tubers harvested from objects sprayed with her- bicides contained 8.1% less phosphorus than the tubers only under the mechanical care.
In other studies, reference  evaluated control of giant ragweed using various POST herbicides in corn and found dicamba/atrazine most effective, ranging from 87% to 94%, while atrazine control was as low as 46%. In dicamba-tolerant soybean, up to 100% control of GR giant ragweed has been reported for dicamba applied POST  and for sequential early- and late-POST dicamba applications . Up to 90% control of GR giant ragweed has been reported for glufosinate under greenhouse conditions ; however, any obstructing vegeta- tion that may be present under field conditions has the potential to decrease control as glufosinate is a contact herbicide and lacks in-plant mobility.
This is a pre-copyedited, author-produced PDF of an article accepted for publication in Journal of Experimental Botany following peer review. The version of record Quareshy, Mussa, Prusińska, Justyna, Li, Jun and Napier, R. (Richard). (2017) A cheminformatics review of auxins as herbicides. Journal of Experimental Botany.is available online at:
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Weed species and densities were determined the day POST applications were made, and those results were used as a basis for HADSS and Expert herbicide applications. The Expert’s recommendations were always made prior to entering the information into HADSS; therefore, the Expert’s decision was unbi- ased and totally independent of HADSS. The Expert attempted to recommend herbicide treatments that would result in the highest net return, weed efﬁcacy, or both. The Expert avoided treatment duplication by selecting different herbicides or rates for the two assigned treatments within a given soil-applied herbicide regime. HADSS treatments were selected from the treatment options based on the highest pre- dicted net returns. Many times, the weed species and densities were similar among plots, which resulted in HADSS recommending identical treatments for the two assigned treatments within a given soil-applied herbicide regime. In 1999, duplication of HADSS recommendations was avoided by selecting the herbi- cide treatment with the next highest net return in the software program. In 2000, the ﬁrst recommended treatment was always selected, which sometimes resulted in duplication. Occasionally, HADSS and the Expert made identical recommendations.
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