No one starts a season planning to lose yield, but the actions you take—or don’t take—throughout the season detract from yield bushel by bushel. If you start the season planting into a field that already has weeds growing, you’ve lost bushels from day one. And when every dollar counts, you need to gain control to save every bushel.
One of the worst yield robbers? Giant ragweed. Highly competitive, this weed can grow up to 16’ in fertile soils. Just one giant ragweed per square meter in soybeans can reduce yield by 52% and two per square meter in corn reduces by 37%, according to University of Illinois.
Scout to catch this weed early. Look for these characteristics:
- Summer annual.
- Hairy stems.
- Cotyledons are round, thick and large with a purple hypocotyl.
- True leaves are opposite, hairy, three- or five-lobed with toothed edges and 4” to 8” wide by 6” long.
- Flowers are green and small on slender stems at the end of branches or bases of upper leaves.
- Resistant to ALS inhibitors (group 2) and EPSP synthase inhibitors (group 9, glyphosate).
If you do find giant ragweed in your fields, use careful management and timing to gain control of this tricky, yield-robbing plant.