Field Facts: Giant Foxtail
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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.
- 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 to 8 inches in length and often droops in an arch shape.
- Reproduction: Seeds, germination occurs in spring
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Fast Facts on Giant Foxtail
- Giant foxtail plants can grow up to 7 feet tall.1
- Soybean yield losses can reach 20% if giant foxtail densities are greater than two plants per square foot, while three giant foxtail plants per foot row can reduce corn yield by 14%.1,2
- On average, a giant foxtail plant will produce 900 seeds throughout a growing season.
- The emergence period is long, and seeds can emerge from soil depths of less than 1 inch.
- 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
- Encourage customers to implement a program approach to weed control with multiple modes of action. This article shares tips for helping customers dial in their program approach.
- Apply postemergence applications early, as it’s easiest to control the weed before it’s 4 inches tall.
- Crop rotation and tillage also can help keep giant foxtail populations down. Michigan State University recommends including alfalfa in rotation to combat the weed.
Work with your customers and your local Corteva Agriscience representative to identify which products and practices make the most sense to control giant foxtail and other problem weeds in your area.
1Clay, S. 2019. Identification of South Dakota Grass and Grass-like Weeds of Importance. https://extension.sdstate.edu/sites/default/files/2020-03/S-0004-30-Soybean.pdf
2Michigan State University. 2023. Giant Foxtail. https://www.canr.msu.edu/weeds/extension/giant-foxtail