Updated: April 8, 2022
Suggestions for Dealing With Herbicide Shortages for 2022
The shortage of glyphosate (Roundup, Gly Star, etc.) and glufosinate (Liberty, Interline, etc.) herbicides are forcing farmers to seek other options for burndown and postemergence spray. No one anticipated this shortage and very little research has been done to address this issue. Many of us had to dust off our notes from the early 1990’s, the time before cheap glyphosate was available. One thing is certain, alternative weed control options will require more targeted management. The key is to plan ahead, select herbicides based on the weeds in the field, and make timely applications. Your mindset needs to be that you are not substituting a herbicide for glyphosate, rather you are using a different herbicide that has its own set of recommendations and limitations. Author: Kurt Vollmer, Univeristy of Maryland Extension Weed Management Specialist, and Mark Van Gessel, University of Delaware Weed Management Specialist; Title: Suggestions for Dealing With Herbicide Shortages for 2022
Updated: March 17, 2022
Understanding Glyphosate and Other Pesticides (FS-1193)
Recent concerns about the widespread use of glyphosate and its potential impacts have propelled this herbicide into the national spotlight. This article provides an overview of the regulatory processes glyphosate and other pesticides must undergo to ensure they do not pose unreasonable risks to human health or the environment. Author: Kurt Vollmer; Title: Understanding Glyphosate and Other Pesticides (FS-1193)
Updated: March 11, 2022
Control of Large Palmer Amaranth and Common Ragweed in Soybean or Corn (FS-1192)
Herbicide-resistant Palmer amaranth and common ragweed are two weed species that pose a major challenge to farmers. It is recommended that an effective postemergence herbicide be applied before these weeds are 3- to 4-inches tall. Palmer amaranth and common ragweed plants that exceed this height are challenging to control. This report summarizes research and discusses the challenges of managing large Palmer amaranth and common ragweed plants. Authors: Kurt Vollmer, Michael Flessner, Dwight Ligenfelter, Vijay Singh, Mark Vangessell, and John Wallace. Title: Control of Large Palmer Amaranth and Common Ragweed in Soybean or Corn (FS-1192)
Updated: November 16, 2021
Managing Herbicide Resistant Common Ragweed Emergence and Growth in Soybean With Cover Crops and Residual Herbicides
Herbicide resistant common ragweed (Ambrosia artemisiifolia L.) is prevalent on the Lower Eastern Shore of Maryland and other areas in the region. In 2019, common ragweed populations on the Eastern Shore of Maryland and Delaware were found to have two or three-way mode-of-action resistance to herbicides. They were resistant to glyphosate (group 9), cloransulam (Firstrate; group 2 “ALS inhibitors”), and/or fomesafen (Reflex; group 14 “PPO Inhibitors”). Early-season management of common ragweed is strongly dependent upon reducing seed emergence and controlling ragweed populations prior to soybean planting. However, due to the limited herbicides with efficacy against common ragweed, it is even more critical to utilize alternative and multiple means of control.
Updated: November 15, 2021
Options for Postemergence Common Ragweed Control in Enlist E3 Soybean
In Maryland, populations of common ragweed have developed resistance to three herbicide groups, Group 9 (glyphosate), Group 2 (FirstRate, Synchrony), and Group 14 (Flexstar, Valor). These herbicide-resistant populations limit options for effective postemergence control. Even though alternative herbicides are available, control can be inconsistent when applied to common ragweed plants exceeding 4” tall (Figure 1).