The synthetic auxin herbicides 2,4-D and dicamba are commonly used for management of glyphosate-resistant and other troublesome weeds. Because of this trend, growers across the Cotton Belt are turning to auxin-resistant cotton. Since the release of auxin-resistant cotton in 2015, the market share has grown to more than 85% in the United States. However, spraying with 2,4-D can be harmful to dicamba-tolerant cotton and spraying with dicamba can cause injury to 2,4-D-tolerant cotton, resulting in yield and economic losses for the cotton producer.
In the webcast "Efficacy of Recovery Sprays to Auxin Injury on Cotton," James Griffin summarizes two studies from 2018 and 2019 that evaluated the effectiveness of available commercial products to recover cotton plants from reduced dicamba and 2,4-D rates when injured at first-bloom stage. Researchers evaluated numerous sprays by assessing the amount of injury and recovery as well as combined lint yields and average boll counts.
No recovery treatments were able to regain yields compared with untreated plots for either 2,4-D or dicamba. Numeric yield gains were shown for almost no recovery sprays over the auxin-only treatments. The trends were inconsistent at best from year to year.
This 6-minute presentation is available through the "Focus on Cotton" resource on the Plant Management Network. This resource contains more than 75 webcasts, along with presentations from six conferences, on a broad range of aspects of cotton crop management: agronomic practices, diseases, harvest and ginning, insects, irrigation, nematodes, precision agriculture, soil health and crop fertility, and weeds. These webcasts are available to readers open access (without a subscription).
The "Focus on Cotton" homepage also provides access to "Cotton Cultivated," a new resource from Cotton Incorporated that helps users quickly find the most current cotton production information available. These and other resources are freely available courtesy of Cotton Incorporated at http://www.plantmanagementnetwork.org/foco.