Managing increasingly hard-to-control and resistant weeds is becoming a greater challenge to the farmer with each passing year. The list of resistant and hard-to-control weeds has grown substantially during the past decade. Faced with few choices, farmers may be forced to employ farming practices that are less environmentally beneficial in order to overcome the growing challenge.

Farmers Face Growing Challenges With Weeds

The development of glyphosate-tolerant crops in the mid-1990s helped farmers to effectively manage weeds in a cost-effective manner. There were also significant environmental benefits associated with planting these crops, including improved soil and water quality and reduced soil erosion and greenhouse gas emissions. Today, glyphosate-tolerant crops have been adopted on 85 to 95 percent of corn, soy and cotton acres in the United States.

"The progression of agricultural products is very important to our business, our environment, and the people that we serve. Being stewards of the land, weed control is very important, and new and improved ways to control these hard to control species of plants is becoming more important every year."
     - Steve Mossbarger, Crop Protection Services

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However, the long-term effectiveness of this system is threatened by increasingly hard-to-control and glyphosate-resistant weeds. Years of widespread and consistent use of glyphosate as the single mode of weed management have contributed to an increase in both the number and geographic distribution of resistant species.

Glyphosate resistance has been confirmed  in 21 weed species worldwide, including 12 in North America, according to the International Survey of Herbicide Resistant Weeds.   During the past decade, the number of resistant species  has increased from zero in 1995 to 21 in 2011, and are now present across 25 states in the United States. In fact, recent studies  show that up to a third of all corn and soybean growers and two thirds of all growers in the south have problems with weed resistance.

To date, the most common hard-to-control and glyphosate-resistant weeds include:

  • Morningglory
  • Pigweed (including Palmer amaranth)
  • Lambsquarters
  • Marestail
  • Waterhemp
  • Giant and common ragweed
  • Velvetleaf
  • Eastern Black Nightshade
  • Kochia

The steadily increasing number of glyphosate-resistant weeds will likely only escalate unless farmers have access to new weed management tools.

New technologies are critical to sustaining the long-term effectiveness of the current production systems. Field experts, including weed scientists, recommend utilizing additional modes of action - employing multiple different herbicides - to manage resistance. For example, the application of residual herbicides reduces in-season weed growth and extends early-season weed control, providing another mode of action for weed control. Utilizing multiple modes of action increases the effectiveness of the herbicides used while decreasing the potential for weeds to develop resistance to any one herbicide. For farmers to meet the increasing global food demands in an environmentally and economically sustainable manner, they must have a solution that will allow them to continue to improve productivity.

 

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