Cover crops not only play an important role in soil health, but also weed control. Cover crops can reduce selection pressure on current, effective herbicide options, and they can also suppress weeds due to the large amounts of biomass they produce. Similar to canopy coverage, biomass will shade the soil and reduce weed emergence.
Beck’s Practical Farm Research (PFR)® team looked at various cover crop treatments across two termination timings: at planting and 21 days after planting (DAP). The team saw greater visual control when they waited 21 DAP, but also saw a reduction in stand.
When terminated at planting, the soybean stands with no cover crop were 96,000 plants/A. and the stands with a cover crop were 99,000 plant/A. However, when terminated 21 DAP, the stands with no cover crop were 107,000 plants/A. and the stands with a cover crop were 77,000 plants/A. Though a reduction in stand was observed, soybeans can compensate for said reduction.
Which Cover Crops Worked the Best?
The longer you wait to terminate the cover crop, the greater the increase in biomass and the harder it will be for the residual product to reach the soil surface. However, an increase in biomass can result in greater weed suppression. Cereal rye, at lower rates, produced less biomass than at higher rates, but still interfered with the herbicide application, making the worst of both worlds. Wheat resulted in the best weed control across the two application timings. Other cover crops, such as hairy vetch or rape seed, had poor growth in the fall due to dry weather. Therefore, the control from hairy vetch was most likely from the Group 15 herbicide and not the cover crop. Termination timing, plus the Group 15 herbicide you select, may influence the success of your cover crop program.
Selecting The Proper Group 15 Herbicide for Cover Crops
Waterhemp residual control is very effective with Group 15 herbicides. However, like any residual herbicide, the product must reach the soil surface. Remember, the longer you wait to terminate the cover crop, the harder it is for the residual product to reach the soil surface because of the increased biomass. Products such as Warrant® contain an encapsulated acetochlor, making it very effective in high biomass scenarios. In the study below, the addition of Warrant to Roundup PowerMAX® provided the most constant level of control across the two application timings. Though terminating at 21 DAP made it more difficult for the herbicide to reach the soil surface, the increase in biomass still improved control. The key is that cover crops alone are not enough for season-long control and adding the proper residual product to your termination herbicide can help improve control.
In addition to reducing selection pressure on current, effective herbicide options, cover crops can suppress weeds due to the large amounts of biomass they produce. Like canopy coverage, biomass will shade the soil and reduce weed emergence. Termination timing of the cover crop plays a role in, and may influence, the success of your cover crop program. Adding the proper residual product to your termination herbicide can also help improve overall control.
For more information contact your local Beck’s representative or click here to access Beck’s herbicide and weed management resources.
Beck's - Farmers At Heart® - revolutionized the customer seed buying experience by remaining true to a foundation built on faith, family, and farming. Founded in 1937, Beck's appreciates the farmers who have helped them become the largest family-owned retail seed company and the third largest seed brand in the United States. The Beck family is now in its fifth generation of family members who work in the business to honor God and help farmers succeed. The Beck family and team of employees help farmers achieve success from generation to generation through authentic customer experiences, product diversity, seed quality, and performance. With a home office located in Atlanta, Ind., Beck's serves farmers throughout the Midwest and Mid-South. For more information about Beck's Superior Hybrids, Inc., visit www.beckshybrids.com.