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The RAAT approach to grasshopper controlBy Michael Fisher Golden Plains Area Livestock Extension Agent A couple of months ago, I wrote an article about grasshoppers. In that article, I discussed the aggressive appetite that these little pests can exhibit and visited with you about setting a schedule on your calendar to be monitoring for grasshoppers on your rangelands. If you have not taken a count yet, you might want to consider it. The grasshopper population is exploding in some parts of Eastern Colorado. Remember that, depending on the species of grasshopper that you are dealing with, from as few as three to as many as 40 grasshoppers per square yard is the point when the economic threshold is reached. In typical rangeland or pastures, the economic threshold is often considered to be 15 to 20 nymphs or eight to 10 adults per square yard. In addition to this, studies suggest that 80 to 104 pounds of grasshoppers will consume the same amount of forage as a 1250 pound cow will on a daily basis. I have been in range pastures this week where the populations were in the 40 plus per square yard range. If you are in that situation, you may be starting to consider your options. With today's prices for fuel and pesticides, it is not a happy prospect. But, if you are contemplating chemical grasshopper controls, you might want to do some research into the Reduced Agent and Area Treatment approach. Detailed information and guidelines for RAAT can be obtained through the University of Wyoming or the USDA-ARS grasshopper website at www.sidney.ars.usda.gov/grasshopper/. However, I will try to summarize the concept. RAAT has two key elements. First is a reduction in the chemical's application rate below the recommendations on the products label. (The aforementioned website gives some product and rate suggestions.) Secondly, RAAT uses swath spraying as opposed to blanket spraying. The swath spraying cuts down on costs, promotes survival of insects that have a positive effect on your rangelands, and allows grasshopper predators a safe harbor outside of the application zone. Research studies using ATV's to implement RAAT have shown a 50 to 75 percent reduction in pesticide applied and a mortality rate only 5 to 15 percent less than a conventional blanket application. Additionally, the cost in this method was approximately 60 to 80 percent that of having an aerial blanket application. RAAT research has also been conducted using airplanes to do the applications. The aerial methods chemical reductions and mortality rates were similar to that of the ATV studies. In some research cases, the aerial RAAT application costs have been reduced by as much as two-thirds from the cost of a blanket application. Along with RAAT guidelines, the previously mentioned website offers a couple of free, downloadable software programs that a rancher can use to help him/her determine when and how to best manage a grasshopper outbreak. These programs will allow you to enter data based on your own operation (such as grasshopper counts from your location) and receive research-based advice that relates directly towards your current conditions. If you have not already done so, make an asserted effort to check for grasshoppers on your operation. As the growing season moves on, be observant and, if you start seeing a lot of grasshoppers, tell your neighbors, your Pest District Supervisor, your Extension agent, or your NRCS range specialist. Communication is one of the real keys to controlling a major grasshopper problem. 6/30/08 Date: 6/26/08 Advertisement
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