Brian Triplett: Ag Biz

Grasshoppers, one of the perennial summer pests of pastures, gardens and landscapes, are showing up on some places in the area in fairly large numbers. Whether you have a problem worth spending the money to eradicate them this year depends upon several factors.

The drier-than-average fall we had last year typically results in an above-average grasshopper crop the next summer. However, the very wet months of June, July and August (when most grasshopper hatching, feeding and egg-laying activity occurs) might have helped keep numbers in check this year. So, if these conditions combined to keep the numbers of grasshoppers very low on your place, consider yourself fortunate and relax a little, you have one less decision to make this summer.

When grasshoppers are present in pastures and hay fields, a decision must be made and economics should be taken into consideration during the decision-making process. Two factors that should be examined when deciding whether to treat are how badly is the forage needed in your operation and how many grasshoppers are present.

The first part of the equation is a decision based upon grasshopper density.

Scouting for grasshoppers is the best way to determine how many you have and if they are present in large enough numbers to warrant spraying. Some fields may have heavier numbers on them than others, and you may want to check each field individually and make spraying decisions based upon levels found in each field. The grasshopper hatch in this area is normally completed by now, so most of the grasshoppers you will encounter will be mature and capable of flying. Egg-laying season for these insects starts about the middle of this month and continues into the fall.

As a rule of thumb, it becomes economical to spray grasshoppers when their numbers caught in a sweep net exceed 25 per square yard, which equals about 120,000 per acre.

The second part of the equation is a decision that must be made regarding how badly the forage is needed in your operation.

If you cut back on fertilizer applications this summer because of high costs and are in an area that is falling behind in rainfall, you might need the forage more than you think. Cutting back on fertility levels will decrease pasture growth responses due to rainfall, and the grass is only going to grow to the extent that the first limiting nutrient stored in your soil bank will allow. If you cut back on stocking rates and/or total number of livestock to compensate for the lower fertilizer inputs you will probably be OK unless your grasshopper numbers are very high.

If you cut back on the number of acres fertilized for hay production, look these remaining hay fields over carefully when making the decision. The cost to treat an acre for grasshoppers will be in the $10 range. I know this is another added expense. However, the expense is not too great compared to the value of the forage that you might be losing.

If you are nearing time to cut a hay field, you might consider cutting it a little early versus spraying, as one of the main products used in grasshopper control has a hay harvesting restriction of 14 days. Yields will be affected when a field is cut early, but the quality of hay produced will be much better than waiting 35 days or more between hay harvests. Higher quality hay will require little to no supplementation during the upcoming winter feeding period, while poorer quality hay will require the addition of expensive protein supplements for most classes of livestock.

Once you have decided that treatment is necessary, select a product labeled for your specific crop and follow all of the label directions. For information on chemicals approved for grasshopper control in pastures and hay meadows, contact the Smith County Extension office at 903-590-2980.

Brian Triplett
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