Ryegrass Emerging As Tough Foe For Wheat, Soybean Growers

LONOKE, ARK.
    Arkansas wheat and soybean producers have another foe in the fields – herbicideresistant ryegrass.
   “Because of years of use in Arkansas, we have a tremendous problem with Hoelon-resistant ryegrass,” said Bob Scott, extension weed scientist for the University of Arkansas Division of Agriculture. “And that product is not really used as much in the state as it used to be.”
    Hoelon resistance in ryegrass was first identified in the early 1990s, he said.
   Arkansas producers and researchers also have been doing battle with resistant horseweed and Palmer Amaranth, also known as pigweed.
   Scott said there are three main options for ryegrass for this phase of the growing season: Axial XL, PowerFlex, and Osprey herbicide.
   “Axial XL is strictly a ryegrass material. It only controls ryegrass in wheat,” he said. “If you have broadleaves you need to tank-mix with another herbicide. Both Osprey and Powerflex will control not only ryegrass, but also a fairly broad spectrum of broadleaved weeds.”
    For fields that also have wild garlic and horseweed “it may be necessary to add a tank-mix partner to the Osprey or the Powerflex,” Scott said.
   Scott said it’s important producers pay attention to the thermometer wen making applications.
    “We like to see night-time temperatures above 45 degrees for optimum activity of post-emergence ryegrass materials in the spring,” he said. “In addition, many of these post-emerge herbicides have got fertilizer restrictions that require anywhere from seven to 21 days between the application of fertilizer and the application of herbicide in order to avoid injury.”
    For more information about ryegrass control in wheat, contact your county extension office, see the podcast “Controlling ryegrass in wheat,” at http://www.aragriculture.org/crops/soybeans/ podcasts/number29_mp3.htm or download FSA2149, “Ryegrass Identification Keys” at www.uaex.edu. Δ