AgWatch

Take Action Now To Rid Fields Of Common Ragweed

GALENA, MO.
    Even under drought-like conditions, this time of year brings a big crop of common ragweed (Ambrosia artemisiifolia) in southwest Missouri pastures according to Tim Schnakenberg, an agronomy specialist with University of Missouri Extension.
   “Ragweed growth has exploded in some Ozarks pastures the past couple of years,” said Schnakenberg. “Timely spring rains encourage germination and seedling growth. Sunny dry fall weather helps seed develop and drought weakens competition.”
   Common ragweed is an annual and is controlled more easily with grazing management or herbicides than western ragweed (which is a perennial).
   Research and observations both show that ragweed problems are worse in pastures that fail to maintain grass competition with a full leaf canopy during late May through late June.
   Any management that develops and maintains a dense canopy at this time helps reduce problems with ragweed. This includes increasing grass growth with fertilizer and thickening stands by seeding, but most important of all is to avoid grazing heavily in areas with ragweed problems.
   “If you do graze heavily or cut hay, one quart of 2,4-D or Grazon after grazing or cutting gives good control of ragweed seedlings and small plants. If ragweed gets away, clipping in September can reduce seed production,” said Schnakenberg.
   Grazon P+D, GrazonNext, and 2,4-D are just a few of the herbicides available for the control of these annual weeds.
    Broadleaf weeds reduce pasture growth for gazing livestock and can inhibit fescue growth going into the fall. Fall growth will be very important to maintain as hay supplies are short this year. The herbicide will control the annual broadleaf plants in the pasture, which include most of the troublesome pasture weeds.
   Herbicides also kill legumes in the grazing mix but those can be re-established with frost seeding next spring.
   “Weeds form a canopy that shade pasture grass leaves, cutting growth for livestock grazing. In management-intensive grazing systems, ragweed in young stages provides nutritious forage,” said Schnakenberg.
    According to information from the Asthma and Allergy Foundation of America, among those Americans who are allergic to pollen-producing plants, 75 percent are allergic to ragweed. Over 30 percent of Americans suffer from “hay fever.” Symptoms include eye irritation, runny nose, stuffy nose, puffy eyes, sneezing and an inflamed and itchy hose and throat. Δ

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