Pest Profile: Fall Panicum and Foxtail Grasses

Persistent and resistant weeds like fall panicum and yellow and green foxtail can damage yields and raise costs.

A Tale of Three Foxtails

The three most common foxtail weeds in the U.S., common in corn and wheat are giant, green and yellow foxtail. Penn State Extension explains the differences between the three types: green and yellow foxtails are named for the color of the fuzzy bristles (awns) on their seeds. Giant foxtail (Setaria faberii) has a large drooping seed head that grows up to 8 inches (20 cm) long.

Once a weed like giant foxtail establishes its foothold in a field, it can take five years to reduce the seed bank by just 50 percent, according to Michigan State University Weed Science. The university also reported that even a very conservative giant foxtail presence – just three per square foot – reduced corn yields by as much as 14 percent. Any type of foxtail is more challenging to control in corn or wheat, as both plants are grasses. In wheat, green foxtail infestations of 97 plants per square meter resulted in a yield loss of 8-44 percent.

Mistaken Identity

A fourth weed is commonly mistaken for green foxtail – fall panicum. According to Penn State Extension, “Both grasses have smooth or sparsely hairy leaf blades, as well as split, partially overlapping leaf sheaths. The leaf sheath margins of green foxtail, however, are densely lined with upward pointing hairs, while those of fall panicum are smooth.” While the differences become more evident in fully-grown plants, they are virtually indistinguishable when they are seedlings.

Fortunately, there is a way to quickly and effectively manage these weeds and protect yields. The University of Missouri Extension recommends using a pre-emergence herbicide as part of a two-pass system to control foxtails and fall panicum.

Solutions for Corn Growers

For season long weed control, a two-pass herbicide program can help growers start clean with weed-free fields and stay clean throughout the season.

For the first pass, a pre-emergence herbicide like Corvus® herbicide (Groups 2, 27), tankmixed with a Harness® Brand Agricultural Herbicide (Group 15) has multiple sites of action to take out weeds that have already come up out of the ground.

In addition to superior control of emerged weeds, Corvus herbicide also provides extended early season weed control due to its long-lasting residual and unique feature of reactivation. With as little as a half inch of rain, Corvus herbicide reactivates to take out additional weeds that may have emerged, even after extended dry periods.

The second pass should include a postemergence product such as DiFlexx® DUO herbicide (Groups 4, 27). DiFlexx DUO herbicide provides powerful control against a full range of tough-to-control weeds. Additional postemergence herbicide options include Capreno® herbicide and Laudis® herbicide for excellent residual control of weeds.

Add an additional site of action to the postemergence application with Roundup® Brand Agricultural Herbicide (Group 9). As the preferred tankmix partner for DiFlexx DUO, Capreno and Laudis herbicides, Roundup Brand Agricultural Herbicides offer enhanced consistency of control of tough weeds, including foxtail.

Answers for Wheat Growers

Chemical weed management is also key for controlling foxtails in wheat. A number of herbicides provide effective control of many key weeds, and Bayer offers three herbicides for controlling green and yellow foxtail. There also are a number of modes of action to choose from to help you manage herbicide-resistant weeds.

For example, Huskie® Complete herbicide is available to wheat growers in Colorado, North Dakota, South Dakota, Minnesota, Montana, Wisconsin and Wyoming. This all-in-one wheat herbicide carries a chemistry previously not available for wheat, controlling green and yellow foxtail along with 50 grass and broadleaf weeds. 

Varro® herbicide, which controls grass weeds, such as green and yellow foxtail and barnyardgrass, and is available in Colorado, North Dakota, South Dakota, Minnesota, Montana and Wyoming. Varro herbicide provides a wide range of choices when it comes to broadleaf tankmix partners—while enhancing the performance of those partners.

Wolverine® Advanced herbicide controls 69 grass and broadleaf weeds in wheat, thanks to three modes of action in a single product. This unique combination of modes of action control green and yellow foxtail and barnyardgrass in addition to broadleaf weeds, such as kochia, Russian thistle, prickly lettuce and wild buckwheat – including ALS-and glyphosate-resistant biotypes. Wolverine Advanced herbicide is available in Idaho, Minnesota, Montana, North Dakota, South Dakota, Washington, Wisconsin and Wyoming.

Talk to your Bayer representative about how to manage difficult weeds in an economically feasible manner.

©2019 Bayer Group. Always read and follow label instructions. Bayer, the Bayer Cross, Capreno, Corvus, DiFlexx, Harness, Huskie, Laudis, Roundup, Varro and Wolverine are registered trademarks of Bayer Group. Corvus and Huskie are restricted use pesticides. Not all products are registered in all states. For additional product information, call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at Bayer CropScience LP, 800 North Lindbergh Blvd. St. Louis, MO 63167

Works Cited

Bradley, Kevin. “Two-pass Corn Herbicide Programs are Almost Always the Best.” University of Missouri. Web. 31 March. 2014.

“Giant Foxtail.” Michigan State University Weed Science. Web. 26 January. 2015.

“Green Foxtail.” Penn State Extension. Web. 26 January. 2015.

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