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®

摘要

Tolpyralate is a new HPPD-inhibiting herbicide thatis efficacious on annual grass and broadleaf weed species in corn. For maximumherbicide performance of tolpyralate, it is recommended that atrazine is tankmixed with tolpyralate along with the adjuvants methylated seed oil concentrate(MSO) plus urea ammonia nitrate (UAN). A common use pattern of tolpyralate plusatrazine 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-reviewedliterature if the adjuvant system in Roundup WeatherMAX®is adequate for optimal herbicide performance of tolpyralate plus atrazine, orif MSO and UAN are still required. Six field trials were conducted over twoyears near Ridgetown and Exeter, ON, Canada to determine if adjuvants are stillrequired 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 ofthis study show that in the absence of Roundup WeatherMAX®,weed control with tolpyralate plus atrazine was improved substantially with theaddition of MSO; however, there was little to no increase in weed control withthe addition of UAN. When tolpyralate plus atrazine was co-applied with RoundupWeatherMAX®, there was no improvement in weedcontrol with the addition of MSO and/or UAN.