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Don’t let hungry grasshoppers eat away at your production

Gerald Hobson Published on 31 March 2013

If you are in the farming and ranching business, a prolonged drought is impossible to ignore. Limited rainfall over the past couple of years has been hard on pastures, rangeland and hay production, as well as on people.

It’s not just minimal moisture that hurts forage production; one of the most aggravating side effects of drought can be a surge in hungry grasshopper populations.

Parts of Texas have been hit hard the last two years with this pest, and current conditions favor a third year of grasshopper pressure.

Grasshoppers are one of the most destructive insect pests forage producers face and can pose a threat any year. In outbreak years, they are particularly damaging, since they tend to consume precious forage that is in high demand.

The Southwest is home to approximately 130 grasshopper species, and as many as 20 species may be present at one time in your pastures.

Some grasshoppers are general feeders and will eat just about any plant in their path, while others are more choosy.

While cattle can eat 1.5 to 2.6 percent of their bodyweight per day, a grasshopper can eat 50 percent of its bodyweight every day. In a 10-acre pasture, seven grasshoppers per square yard will consume as much grass as one cow.

It is also estimated that 62 grasshoppers per square yard will eat as much as 2.5 animals weighing a total of 2,500 pounds.

The economic threshold for grasshoppers, or the point at which it is necessary to control them, ranges from state to state.

Severe to threatening infestations range from eight to 28 grasshoppers per square yard, while 28 or more grasshoppers per square yard is considered a severe infestation.

In the last few years, some parts of Texas have seen grasshopper pressure at even higher rates. Early in the season, consult your local forage or extension specialist for local trends and recommendations on thresholds in your area.

Hoppers like it hot and dry
Grasshoppers thrive in hot, dry weather. Warm temperatures help ensure their survival and usually result in an increase of severe infestations.

Grasshopper eggs are deposited in the fall and will survive from the previous year regardless of how far winter temperatures fall.

The eggs hatch in the early spring as the soil temperatures begin to warm. Each species will develop at their own rate, so we tend to see a continual hatch of new grasshoppers over several months.

As eggs hatch, newborn grasshoppers (nymphs) begin to feed on grasses within the first few days of life. They continue feeding through all five nymph stages, for as long as 55 days.

Nymphs appear as early as February in some parts of southern Texas or as late as June or July in other areas.

Because of the prolonged drought, grasshoppers are becoming more of a problem every year. Once rains begin, grasshoppers contract a fungus that naturally monitors their population. Until then, scouting and strategic insecticide applications are your best defense.

Early awareness is your advantage
Scout pastures and initiate control measures early, as grasshoppers are much easier to manage in their susceptible nymphal stages than once they’re fully grown.

Also, the earlier you control them, the less forage they will have consumed, so watch for favorable grasshopper conditions early in the season. Grasshoppers are eating machines that want the grass you have worked so hard to produce.

Insecticides are a good way to control mounting or extreme grasshopper infestations. Look for products with residual activity to manage populations even after the sprayer pulls out of the pasture. Check the label before applying any insecticide.

Good pasture management speeds recovery
The best way to help protect your land from an infestation is to be proactive. Good pasture management practices can help stands rebound from the effects of a grasshopper outbreak and help you prepare for future infestations.

With our current weather patterns, it is important to have a drought management plan. If you haven’t received 50 percent of your annual rainfall by May or June, implement your drought plan.

To care for an area that has been damaged by grasshoppers and drought, start with the soil. Test soil in the fall or late winter and set realistic goals for recovery.

Determine which nutrients your pastures and grasses need and discuss how to provide them with an agronomist or crop consultant.

Providing a pasture with adequate nutrients, including both macronutrients and micronutrients, will produce more forage even with limited rainfall.

Weed control is also important. Broadleaf and undesirable weedy grasses take valuable nutrients and moisture away from pasture grasses.

By minimizing undesirable growth in your pasture from the start, you help provide desirable grasses with optimal nutrition and help pastures recover from damage.

Avoid overgrazing, since an overgrazed pasture is less able to absorb rainfall and is more susceptible to erosion. Grazing or haying management in a drought is critical for the long-term health of rangeland and pastures.  FG
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Gerald Hobson
Range and Pasture Specialist
DuPont Crop Protection


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