TITLE:
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®
AUTHORS:
Nicole M. Langdon, Nader Soltani, Alan J. Raedar, Darren E. Robinson, David C. Hooker, Peter H. Sikkema
KEYWORDS:
Biomass, Broadleaf Weeds, Corn, Efficacy, Grassweeds, Roundup WeatherMAX, Methylated Seed Oil, Urea Ammonia Nitrate, Weed Control, Yield, Zea mays L
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.11 No.3,
March
27,
2020
ABSTRACT: 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.