Results from Recent Cover Crops Research
The advent of herbicide-resistant (HR) weeds has caused Midsouth soybean producers to look for alternatives to herbicides to assist in weed control. Of particular importance to Midsouth producers is the elucidation of management tactics that can be used to offset the problematic selection of Palmer amaranth (pigweed) for biotypes that are resistant to several herbicide modes of action. In a White Paper on this website, this is addressed in detail.
Recently, increasing attention has been given to the use of cover crops to aid in the suppression of early-season HR pigweed populations in the Midsouth. This is addressed in another White Paper on this website. Myriad research projects that address this component of cover crop use are now underway throughout the US soybean belt.
One such project looks at how time of termination of a cereal rye cover crop in relation to time of soybean planting may affect the emergence of pigweed in the planted soybeans. Preliminary results from this project are covered in a video presentation by Dr. Jason Norsworthy of the University of Arkansas. The premise for this research is that later termination of the cover crop in relation to soybean planting date will result in more biomass accumulation by the cover crop, which is the key to suppression of weeds that will normally emerge in the planted soybean crop. Hopefully, final results from this project will provide information about this aspect of cover crop termination in relation to varied soybean planting dates–e.g. April 10 vs. May 10–since the biomass accumulation of the cover crop will be quite different prior to the different soybean planting dates.
Dr. Norsworthy’s work is part of an Area-Wide Integrated Weed Management Project (see video) supported by the USDA-ARS that includes ongoing research by 15 weed scientists across the US soybean belt. This project is assessing how multiple tactics–including cover crops–in the weed management toolbox can be used to aid in controlling HR weeds. The final year of this project is 2019. The project website also links to a clearinghouse of weed management resources that can be considered for an integrated weed management program for soybeans.
Another aspect of cover crops use in crop production systems is how it may affect early-season insect populations that could impact a following soybean crop. The MSPB funded a recently-completed project (No. 13-2018) titled “Influence of cover crops on early-season insect pest dynamics in Mississippi soybeans” to evaluate this. An Executive Summary of the results from this research, and a dissertation and seminar by Dr. Adam Whalen provide details about this research and its findings.
Composed by Larry G. Heatherly, Jan. 2019, larryheatherly@bellsouth.net