Plan now to avoid grasshopper damage in yards and gardens
July 20, 2010
LINCOLN, Neb. – Now is the time for Nebraskans to be watching their yards and gardens for grasshopper damage, University of Nebraska-Lincoln entomologists say.
Grasshoppers are already starting to damage gardens in some areas. The potential for grasshopper damage increases as summer progresses, said Bob Wright, UNL Extension entomologist.
“Adults move into yards and gardens in July and August,” he said. “Severe problems can arise when adjacent agricultural crops or grasslands mature or are harvested and grasshoppers move to find new food sources.”
Grasshoppers show a preference for flowers and some garden vegetables, such as lettuce, beans and sweet corn, but when populations are high they will feed on nearly all garden vegetables, as well as trees and shrubs, said Ron Seymour, UNL Extension educator in Adams County.
Grasshopper management can be effective and practical if the area to be protected is relatively small and isolated; however, protecting a garden from grasshoppers moving out of a large area of adjacent grassland or cropland may be impossible, Seymour said.
Several strategies can be used to help manage grasshopper problems:
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– The preferred egg-laying and early season feeding areas for the grasshopper species of concern are weedy, untilled areas, such as vacant lots, ditches and poor pastures with mixed grass and broadleaf plants. Dense grass growth or regular tillage of these areas will reduce grasshopper numbers.
– Where the grasshopper source covers a large area and outbreak populations are expected, the best strategy may be to attempt grasshopper control in the surrounding hatching area while the grasshoppers are small and easily controlled. Row covers and screens can help protect more valuable plants, but grasshoppers can eat through most fabric screens. Aluminum window screen is the best option.
– Irrigation can be used to keep vegetation in surrounding areas green so grasshoppers will not move into the garden as readily.
– Leaving border areas unmowed will delay grasshopper movement into the yard and garden. Tall grass provides food and shelter for the grasshoppers.
– A border area of attractive plants, such as zinnias or some other lush flower or vegetation can be planted around the edge of the garden to attract and hold grasshoppers. Also, these areas can be sprayed with insecticide to reduce populations.
– Organic gardeners recommend planting cilantro on the border of the garden as a repellant crop, or using garlic sprays as a repellant.
– Chemical control is often the best alternative for quickly eliminating large infestations of grasshoppers. Adult grasshoppers are difficult to control with insecticides due to their size and decreased susceptibility to the insecticides. The best time to control grasshoppers is when they are 1/2 to 3/4 inch long. At this time most eggs will have hatched and the young hoppers will be more susceptible to insecticides.
– There are many insecticide options available for yard and garden use. Read and follow all directions and precautions on the insecticide label. Most products are formulated in a liquid or mixable dry formulation, and will be registered for use on certain vegetables, turf, ornamentals, or non-crop use. The same active ingredient may be found in numerous different brand name products.
– The sources of grasshopper infestations, such as surrounding grasslands, ditches and other untilled areas should be treated before the larger adult hoppers move out. If homeowners do not own the adjacent areas, they should make arrangements with their neighbors to spray areas up to 150 feet around their garden. If this is not possible, the only option is to use insecticide or repellent sprays to protect as much of the yard and garden as possible. These insecticides will have only a few days of residual activity and repeated applications will be necessary. If most grasshoppers are adults, the best control will be obtained by using the maximum labeled insecticide rates for these products.
– Commonly used insecticides for yards and gardens include those with the active ingredients of carbaryl, malathion and permethrin. Always check the label for application instructions, rates and safety precautions.
For more information, contact a local UNL Extension office for a more complete list of insecticides for grasshopper control in and around the yard and gardens.
For additional information see NebGuide G1633, A Guide to Grasshopper Control in Yards and Gardens, available from your local UNL Extension office or online at http://www.ianrpubs.unl.edu/sendIt/g1633.pdf and http://grasshoppers.unl.edu.