What is in this article?:
- Herbicide-resistant marestail drives fall weed control
- Weed control’s yield impact
Fewer spring (marestail) weed worries, earlier planting access, reduced black cutworm and SCN overwintering host potential and reduced equipment needs and field passes are why some growers apply residual herbicides in the fall.
Charles Hardy’s fall residual herbicide applications enable him to grow corn, soybeans and wheat on several thousand acres in Sedalia, Mo., with one less combine, one less planter and one less trip across the fields.
Because of their reliance on effective herbicidal weed control, no-till and strip-till growers battling winter annual weeds, especially herbicide-tolerant marestail, appear to have the most to gain from applying residual herbicides in the fall. This image, taken April 29 in Houghton, Iowa, compares a field treated Nov. 28, 2012, with 1 ounce of DuPont Basis Blend, 0.15 ounce of Express TotalSol and 10 ounces of 2-4,D against an untreated check.
More adverse spring weather and the northern spread of herbicide-resistant marestail find more reduced-tillage farmers considering fall residual herbicide applications. “Fall applications have risen dramatically in the last few years and will continue to grow,” says Regan Wear, CHS agronomy manager in Shipman, Ill. “Erratic, wet, cold springs have narrowed the planting window and fueled interest in fall residual herbicide applications because they really sharpen up timing the following spring.”
Key to the fall residual herbicide application decision is to determine whether these applications’ yield and income contributions will offset the investment.
These factors may contribute to the yield and profit impact of fall residual herbicide applications
- Planting earlier in warmer, cleaner seed beds
- Reduced need/expense for spring burndown herbicide applications
- Reduced weed competition
- Decreased SCN and black-cutworm damage from controlling alternate host weeds.
“The return on investment from fall applications comes from the ability to plant early,” Wear says. “Winter annuals (see sidebar) can create a salad bowl that’s really hard to get through and can force extra tillage passes to get the weeds down.
“Fields sprayed in the fall are our first fields planted and could see a 20% increase in yields compared to corn planted later.” “Farmers invest so much in seed today,” says Jeff Carpenter, DuPont Crop Protection corn herbicide portfolio manager, “that $12-$15 spent in the fall can result in better spring weed control and earlier planting so that the seed has greater opportunity to achieve its genetic potential.”
Long-term, fall residual herbicide applications can help protect the productivity and land values by preventing herbicide-resistant weeds’ establishment. Fall residual herbicide applications can also add an additional site of action to resistant weed-management programs, Carpenter adds.