|Grasshoppers damage more than crops|
By Robert Tigner
SW4 Agricultural Extension Educator
A few samples and recent questions to the UNL Extension Office have brought an unusual tree predator to my attention, grasshoppers.
Over 100 species of grasshoppers occur in Nebraska, but four species cause the majority of damage. Generally, grasshopper populations will fluctuate in cycles. High or very high populations may be present for two to four years followed by low to moderate populations for several years.
However, even when populations are relatively low, grasshoppers in and around the garden can be a nuisance. In outbreak years, grasshoppers can virtually destroy unprotected gardens and threaten small trees and shrubs.
Last year, our area of Nebraska had some very high populations. A few projections are for a strong probability that the same, or higher populations, could occur this year as well.
The damage you will see on trees will be on the smaller branches and will appear as if the most tender and green parts of the branches were stripped of bark. The ends of those branches are now brown and dead since nutrients cannot flow to that portion of the branch. Some wound repair may also have taken place late last year. However, the only option for that branch is to prune.
There are three stages in the grasshopper life cycle. These are the egg, nymph and adult.
The best time to control the grasshoppers is when they are in the nymph or juvenile stage. Chemical control is often the best alternative for eliminating heavy infestations of grasshoppers.
Adult grasshoppers are difficult to control with insecticides due to their size and decreased susceptibility to the insecticide. The best time to control grasshoppers is when they are ½ to 3/4 inch long. These stages will occur in mid to late June.
Most eggs will have hatched and the young hoppers will be more susceptible to insecticides. In addition, they will be concentrated in their hatching areas, and they can be controlled more effectively than when dispersed later in the summer.
Scouting trees and garden areas starting early June will help determine whether control measures need to be taken. The sources of grasshopper infestations such as surrounding grasslands, ditches and other untilled areas should be treated before the larger adult hoppers move out.
Products containing active ingredients such as carbaryl, acephate, befenthrin, cyfluthrin esfenvalerate, Malathion, and permethrin will generally do a good job of eliminating the young grasshopper nymph. Read and follow all label directions as to their use. NebGuide G1366 gives more background information on grasshoppers.
If you need further information call your local UNL-Extension office or the office at Imperial, 308-882-4731.