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After this mild winter, weeds might reach an advanced growth stage earlier than usual.
Add residual at preplant
Weed specialists say that an early start to the weeds doesn’t always correspond to an early planting date and therefore producers may need to adjust their spraying regimen. “Just because weeds emerge earlier doesn’t mean growers will necessarily plant earlier,” says Helen Flanigan, product development manager with DuPont. “Because weeds could have a significant head start before conditions are right for planting, growers should use a residual herbicide as part of their preplanting weed control program. Growers who use a simple contact herbicide burndown approach will likely see more weeds germinate before they are able to get back into the field to plant.”
Scouting early, and scouting often, is always recommended. But this year, your scouting calendar should be moved up. “Higher survival of winter annual and biennial species that emerged last year will mean weed densities will likely be higher, and the plants themselves might be larger by the time management practices are implemented,” says Aaron Hager, University of Illinois weed specialist. “Certainly scouting should be done before any preplant herbicide application is made. Producers should know what species are present and the size of the weeds before selecting a burndown herbicide. The only way to effectively select the product and the application rates is to know what’s growing and its size.”
Program options for growers depend on geography and weed pressure, but in general more northern geographies should consider a burndown application that also provides residual control. In more southern geographies, growers may need to apply a burndown application early and follow it with a residual application at planting.
“Winter annual weeds become very difficult to control once they reach the reproductive stage,” Westberg says. “Getting adequate spray coverage of weeds is also a major concern with large, dense weed populations.”