Grasshopper outbreak predicted to be a whopper
By 06/01/2000 00:00:00
Ellis County Press
Grasshoppers by the millions have hatched in Ellis County. Trees, shrubs, grass and crops are in danger this summer according to Glen C. Moore, County Extension Entomologist - IPM, Ellis/Navarro County. Grasshopper outbreaks could be much more destructive this year than the summers of 1998-99.
Moore stated in a report the forecast is based on the number of egg pods laid in the soil last fall and a dry spring that has been most favorable for egg hatching and nymphal development.
The report also stated the overwhelming number of immature hoppers (nymphs) currently observed in pastures, roadside ditches and waterways certainly supports the notion that grasshopper outbreaks maybe worse for the summer of 2000.
Weather is the main factor affecting grasshopper populations. Outbreaks are usually preceded by several years of hot, dry summers and warm and dry conditions in both fall and spring.
Dry conditions favor nymphal and adult grasshopper survival. A warm and dry fall allows for extended oviposition of egg pods in the soil. Additionally, and perhaps importantly a warm and dry spring minimizes the impact of natural diseases that help to keep the grasshopper numbers in check.
Throughout history, plagues of grasshoppers developed over several dry seasons with damaging infestations lasting from 3 to 5 years, depending on the climate.
Grasshopper management is best achieved through an integrated approach employing the use of cultural practices, biological control, baits and frequent application of foliar insecticides.
Cultural practices include:
Close mowing creates a buffer between tall grass areas and desirable crops, plants and trees. The buffer zone should be enlarged during times of drought when hopper migration is heaviest.
Destruction of grown-up fence rows and ditch banks, etc., that harbor large numbers of hoppers. These are excellent oviposition sites where grasshoppers can lay egg pods in non-disturbed soil.
Spring cultivation destroys egg pods and exposes them to predators. Consequently grasshopper infestations are often relatively light near homesteads surrounded by cultivated fields. In contrast, heavy grasshopper outbreaks are more prone to occur near homesteads adjacent to rangeland and abandoned and/or grown up ditch banks and roadsides.
Commercial tree wraps may be used to protect the bark of young trees. In addition to providing some protection from grasshoppers, this practice also aids in protection from sunscald. Vinyl tree protectors or Guard-Tex Tree Wrap and others may be obtained from area nurseries. Additionally, white tree trunk paint may provide some protection.
· During warm and humid conditions fungus often causes locally high mortality of grasshoppers. Also a protozoan called Nosema locustae is often present to some extent in the grasshopper populations, however it generally does not cause significant mortality. Nosema locustae can be purchased in commercially prepared products such as Semaspore, Nolo Bait or Grasshopper Attack. However, these are not effective in drought conditions and work best before the hoppers have matured.
· Where practical, guineas, turkeys and chickens may provide grasshopper suppression.
· A sevin bate is labeled for use by United States Department of Agriculture personnel.
· You may treat crops, ornamental plants and trees with foliar insecticides. During heavy periods of grasshopper migration, the intervals between insecticide applications may need to be shortened to two to four days.
· Some insecticides that offer the longest residual activity are Orthene and some of the Sevin products.
· Carefully read product labels for application rates, registration for specific crops and precautions.