Influence of Adjuvants on the Efficacy of Tolpyralate plus Atrazine for the Control of Annual Grass and Broadleaf Weeds in Corn with and without Roundup WeatherMAX^®

Tolpyralate is a new HPPD-inhibiting herbicide that is efficacious on annual grass and broadleaf weed species in corn. For maximum herbicide performance of tolpyralate, it is recommended that atrazine is tank mixed with tolpyralate along with the adjuvants methylated seed oil concentrate (MSO) plus urea ammonia nitrate (UAN). A common use pattern of tolpyralate plus atrazine will be in a tank mix with Roundup WeatherMAX®due to the high proportion of corn acres that are seeded to Roundup Ready®hybrids in Eastern Canada. There is no information in the peer-reviewed literature if the adjuvant system in Roundup WeatherMAX®is adequate for optimal herbicide performance of tolpyralate plus atrazine, or if MSO and UAN are still required. Six field trials were conducted over two years near Ridgetown and Exeter, ON, Canada to determine if adjuvants are still required when tolpyralate plus atrazine is tank mixed with Roundup WeatherMAX®in corn. Tolpyralate plus atrazine plus MSO and Roundup WeatherMAX®plus tolpyralate plus atrazine provided excellent control of velvetleaf, pigweed spp, common ragweed, lambsquarters, ladysthumb, wild mustard, flower-of-an-hour, barnyardgrass and green foxtail in this study. Results of this study show that in the absence of Roundup WeatherMAX®, weed control with tolpyralate plus atrazine was improved substantially with the addition of MSO;however, there was little to no increase in weed control with the addition of UAN. When tolpyralate plus atrazine was co-applied with Roundup WeatherMAX®, there was no improvement in weed control with the addition of MSO and/or UAN.

Broadleaf Weed Control with Halosulfuron Tankmixes in White Bean

Six field trials were conducted over a four-year (2017-2020) period near Exeter and Ridgetown, Ontario to determine the efficacy of halosulfuron tankmixes applied postemergence to control broadleaf weeds in white bean. Halosulfuron caused up to 4% injury in white bean at 2 and 4 weeks after treatment (WAT). Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen caused 2% - 16% injury at 2 WAT and up to 3% injury at 4 WAT in white bean. The addition of halosulfuron to the aforementioned herbicides did not accentuate white bean injury. Reduced weed interference with the herbicides evaluated increased white been yield 50% - 90% compared to the weedy control;there was no difference in seed yield among herbicide treatments evaluated. At 4 WAT, halosulfuron at 25, 37.5 and 50 g ai ha-1 controlled velvetleaf 86%, 93% and 97%;redroot pigweed 83%, 85% and 89%;common ragweed 90%, 93% and 94%;common lambsquarters 27%, 28% and 36%;flower-of-an-hour 66%, 76% and 69%;and wild mustard 100%, 100% and 100%, respectively. Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen controlled velvetleaf 73%, 14%, 52%, 42% and 68%;redroot pigweed 40%, 91%, 85%, 75% and 80%;common ragweed 36%, 81%, 92%, 68% and 84%;common lambsquarters 87%, 39%, 48%, 60% and 76%;flower-of-an-hour 90%, 66%, 63%, 73% and 83%;and wild mustard 97%, 97%, 100%, 99% and 100%, respectively. Halosulfuron tankmixed with bentazon, acifluorfen, fomesafen, bentazon/acifluorfen or bentazon + fomesafen controlled velvetleaf 90%, 51%, 68%, 75% and 90%;redroot pigweed 80%, 99%, 95%, 92% and 91%;common ragweed up to 94%, 97%, 93%, 94% and 95%;common lambsquarters 74%, 62%, 43%, 62% and 66%;flower-of-an-hour 92%, 78%, 74%, 82% and 87%;and wild mustard 100%, 100%, 100%, 100% and 100%, respectively. Weed density and dry biomass followed the same trend. This study concludes that the optimal halosulfuron tankmix is broadleaf weed species specific for weed management in dry bean production.

500 g/L乙氧呋草黄·苯嗪草酮悬浮剂防除甜菜田阔叶杂草的效果及对甜菜产量的影响

为明确500 g/L乙氧呋草黄·苯嗪草酮悬浮剂对甜菜田一年生阔叶杂草的防除效果和对甜菜田的安全性,于甜菜播后苗前土壤喷雾使用,定期调查杂草防效及其对甜菜安全性的影响。结果表明:500 g/L乙氧呋草黄·苯嗪草酮悬浮剂使用剂量为3 750~5 250 g a.i./hm^(2)时,药后15、30、45 d,对甜菜阔叶杂草(灰藜、反枝苋、龙葵)的总草株防效分别为100%、79.28%~84.68%、81.52%~86.51%,药后45 d时鲜重防效与株防效结果基本一致,且在试验剂量下对作物出苗、生长发育及产量无明显影响。500 g/L乙氧呋草黄·苯嗪草酮悬浮剂可以有效防除甜菜田一年生阔叶杂草,推荐使用剂量为3 750~5 250 g a.i./hm^(2)。

不同种类杂草危害对水稻产量影响

在常年稻田中设置禾本科杂草、莎草科杂草、阔叶类杂草以及混合杂草自然发生区,研究不同种类杂草危害对水稻产量的影响。结果表明,禾本科杂草区以稗草(Echinochloa crusgalli)为主,密度为102.8茎/m2,产量损失为65.09%;莎草科杂草区以异型莎草(Cyperus difformis)为主,杂草密度为240.2茎/m2,产量损失为56.82%;阔叶类杂草区以节节菜(Rotala indica)为主,杂草密度为183.6茎/m2,产量损失为31.84%;混合杂草区杂草群落主要以稗草(Echinochloa crusgalli)+异型莎草(Cyperus difformis)+节节菜(Rotala indica)为主,总密度为253.2茎/m2,产量损失达70.51%。禾本科杂草区、莎草科杂草区、阔叶类杂草区水稻产量差异显著;以杂草单茎危害率衡量不同类型杂草对水稻产量损失的影响依次为禾本科杂草>莎草科杂草>阔叶类杂草。

山东盐碱地棉田不同杂草群落对棉花产量影响研究

于2011和2012连续2年在山东省高唐县盐碱地棉田中人为设置无草区、禾本科杂草、阔叶杂草以及混合杂草自然发生区,研究了不同杂草群落危害对棉花产量的影响。结果表明,禾本科杂草区以牛筋草、狗尾草、芦苇等为主,2年总密度分别为202.0和291.6茎/m2,棉花产量损失为24.3%和20.3%;阔叶类杂草区以藜、马齿苋、鳢肠等为主,2年总密度分别为230.5和122.2茎/m2,产量损失为27.1%和60.2%;混合杂草区2011年以藜、牛筋草、稗草为主,2012年以藜占绝对优势,其次为马齿苋、牛筋草等,总密度分别为277.0和201.0茎/m2,产量损失为37.5%和68.4%。综合2年试验结果,在盐碱地环境中,阔叶杂草对棉花的单茎损失率大于禾本科杂草;杂草危害造成棉花的产量损失表现在直接影响棉花的产量构成因素,其中对棉花成铃数的影响最大,杂草混合生长区成铃数2年比无草区分别减少34.0%和72.0%,阔叶杂草和禾本科杂草生长区可减少10.8%～53.6%;另外,杂草危害可使棉花株高降低0.4%～18.7%,棉花果枝数降低11.9%～18.0%,棉花单铃重减少6.3%～18.2%;棉花的保苗率减低0～3.6%。杂草对棉花产量影响程度大小与田间杂草种类、密度、生长量以及棉花品种的生物学特性密切相关,温度和降水等气候因素对盐碱地杂草群落组成以及杂草与棉花之间的竞争性关系也有较大影响。

棉田不同杂草群落对棉花生长和产量的影响

于2011～2012年在山东省茌平县棉田中人为设置无草区和禾本科杂草、莎草科杂草、阔叶类杂草、混合杂草自然发生区,研究了不同杂草群落对棉花生长和产量的影响。结果表明,禾本科杂草区以牛筋草[Eleusine indica(L.)Gaertn.]为主,总密度为338.75～505.13茎/m2,棉花产量损失为69.7%～69.8%;莎草科杂草区以异型莎草(Cyperus difformis L.)为主,杂草密度为260.75茎/m2,产量损失为57.7%～59.4%;阔叶类杂草区以藜(Chenopodium album L.)、醴肠[Eclipta prostrata(L.)L.]为主,杂草总密度为208.25～316.0茎/m2,产量损失为87.5%～88.9%;混合杂草区杂草群落2011年主要以藜、醴肠、牛筋草等为主,2012年以牛筋草、异型莎草为主,总密度为366.00～410.0茎/m2,产量损失达90.5%～90.7%。以杂草单茎危害率衡量不同类型杂草对棉花产量损失的影响依次为阔叶类杂草>莎草科杂草=禾本科杂草。杂草危害直接影响棉花生长,对棉花产量构成因素均有影响,其中对棉花成铃数影响最大,杂草生长区比无草区成铃数减少45.2%～87.3%,果枝数减少21%～64%,单铃重减少6.7%～24.5%。此外,杂草的生长也直接威胁到棉花植株的保苗效果。

不同类型杂草危害对小麦产量的影响

通过人工设置不同类型杂草自然生长区,研究不同类型杂草对小麦产量的影响。试验结果表明,在以日本看麦娘(Alopecurus japonicus)和菵草(Beckmannia syzigachne)为优势种群的禾本科杂草自然生长区、以牛繁缕(Malachiumaquaticum)和小藜(Chenopodium serotinum)为优势种群的阔叶类杂草自然生长区、以日本看麦娘+菵草+牛繁缕为优势种群的混合杂草自然生长区和无草区中,以无草区实测产量最高,为407 kg/667m2,禾本科杂草生长区小麦实测产量为329.8 kg/667m2,阔叶杂草生长区小麦实测产量为302.5 kg/667m2,混合杂草生长区小麦实测产量为280.9 kg/667m2。对比无草区,禾本科杂草生长区、阔叶杂草生长区和混合杂草生长区的产量损失率分别为18.94%、25.60%和31.00%。方差分析结果显示,禾本科杂草自然生长区、阔叶类杂草自然生长区和混合杂草自然生长区小麦产量损失率差异显著(p<0.05),按损失率高低排列为混合杂草自然生长区>阔叶杂草自然生长区>禾本科杂草自然生长区。