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Since fall temperatures are still conducive for herbicide applications, growers should consider applying fall herbicide treatments. An effective way to control winter annuals and some perennials is to manage/control them with fall herbicide applications.
Figure 1. Fall emerged mouseear chickweed and henbit.
Weed Species. Some winter annual weeds to look for include common and mouseear chickweed and henbit (Figure 1), downy brome, henbit, little barley, marestail (Figure 2), and purple deadnettle.
General Application. The exact herbicide treatment depends on what weeds are being treated. To reduce pressure from winter weeds, consider a herbicide application of Roundup WeatherMAX® or Roundup PowerMAX® at 32 fl oz per acre, tankmixed with 2,4-D at one to two pints per acre or .5 pint of dicamba. Use the higher rate of 2,4-D for glyphosate-resistant marestail.
Figure 2. Marestail.
Make applications before a heavy frost or freeze to actively growing weeds. Review the cut-off date and soil temperatures on the herbicide labels before application. The majority of herbicides recommend applying the product while the soil is cool, not frozen. For growers planning to apply herbicides with fall fertilization, it is important to remember that the recommended soil temperature is below 50 °F and look for actively growing vegetation.
Fall applications do not eliminate the need to scout in the spring. Recommended weed control programs for glyphosate tolerant crops include a fall application if needed, a spring preemergence application of a residual herbicide, and one or two in-crop applications of a Roundup® Brand Glyphosate Only Agricultural Herbicide. Tank mix additional postemergence herbicides with different sites of action as needed. Fall herbicide applications reduce weed pressure and help prepare fields for planting and emergence. Preemergence applications of residual herbicides can reduce weed pressure, help protect yield potential, and are recommended in all cropping systems. There is evidence that keeping fields clean during the winter can help reduce early spring infestation from insects such as black cutworm and armyworm.
Multiple, timely herbicide applications are key components of a successful weed management strategy. Fall applications to control winter annual and perennial weeds can be a great first step to set the stage for effective weed management in next year’s corn and soybean crops.
Visit RoundupReadyPLUS.com for additional information and consult with your local Asgrow® and DEKALB® Brands Seed Representative for more information.
1 Leer, S. 2002. Fall herbicides wage cold war on winter annual weeds. Purdue News. Purdue University. https://news.uns.purdue.edu/html3month/021016.Nice.herbicides.html Web site verified 8/31/16. 160901214144