*This content was previously published by Corteva Agriscience.
Many fields in the Midwest have a mixture of giant, yellow and green foxtail. However, giant foxtail often emerges before planting and accounts for more yield loss than yellow or green foxtail at similar densities. In fact, this clumping summer annual grass ranks among the most problematic grass weeds across North America. Arm your customers with the information that follows to help them protect their yield potential before this pest escapes control.
Common name: Giant foxtail
Scientific name: Setaria faberi
Leaf shape: Long, thin and ovular with pointed ends
Flowers: Cylindrical seed head with bristles. The seed head is usually green in color, is 3 inches to 8 inches in length and often droops in an arch shape.
Reproduction: Seeds, germination occurs in spring
GIANT FOXTAIL FACTS
- Giant foxtail is native to eastern Asia. It was introduced accidentally in the United States in the 1920s as a contaminant of other grain. Giant foxtail has since spread and can now be found in every state in the U.S.
- It grows well in sandy to loamy soils and disturbed areas and is a notable issue in the Corn Belt. • Giant foxtail plants can grow up to 7 feet tall.2
- For spring-germinating giant foxtail, flowering generally starts mid-summer. It often keeps flowering and producing seed until cold weather arrives.
- On average, when competing with corn and soybeans, a single giant foxtail seedhead produces around 1,500 seeds.
- The emergence period is long, and seeds can emerge from soil depths of less than 1 inch.
- Common seed dispersal occurs via contamination in seed grain, birds, irrigation water and humans with farm machinery.
- Seed viability length in soil depends on the type of soil management. In tilled soil, testing has shown few survivors after two years and no survivors after three years of burial.
- Weedscience.org lists herbicide-resistant giant foxtail in Illinois, Indiana, Iowa, Maryland, Michigan, Minnesota, Pennsylvania and Wisconsin. This weed has shown resistance to Groups 1, 2 and 5 herbicides.
CONTROL TIPS
- Tillage – Manipulating the timing and depth of tillage can influence emergence and help manage giant foxtail because giant foxtail germinates on or near the soil surface.
- Cover crops – Weed density and competitiveness may be reduced by planting cover crops. Research in no-till soybeans indicated moderate to heavy cover crop residue reduced foxtail species density by 85%.3
- Crop rotation – Rotating to alfalfa for two years has been shown to deplete the weed seed bank and reduce giant foxtail density.
- Herbicides – An important tool in the fight against giant foxtail, herbicides should be applied when the plants are small for maximum effectiveness. Apply a residual herbicide at planting along with a timely postemergence application that includes a soil residual herbicide. Postemergence applications should be done early, as it’s easiest to control the weed before it’s 4 inches tall.
- Program approach – A program approach to weed control with multiple modes of action is recommended in controlling giant foxtail.
Giant foxtail can be a giant problem, but it doesn’t have to be. As a licensee, you can partner with your local Corteva Agriscience account manager to identify the most effective products and practices to share with your customers and help them ensure top control of giant foxtail and other problem weeds in your area.
1 “Giant Foxtail,” Michigan State University Department of Plant, Soil and Microbial Sciences, Weeds, Accessed January 13, 2026, https://www.canr.msu.edu/weeds/extension/giant-foxtail.
2 Sharon Clay, “Identification of South Dakota Grass and Grass-Like Weeds of Importance,” SDSU Extension iGrow Soybean Best Management Practices, 2019, https://extension.sdstate.edu/sites/default/files/2020-03/S-0004-30-Soybean.pdf.
3 C. Rankrape et al., “Giant Foxtail,” GROW (Getting Rid of Weeds), 2025, https://growiwm.org/wp-content/uploads/2025/01/Giant-Foxtail-Factsheet.pdf.
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