Grasshoppers Pose Threat to Winter Wheat

Since a recent news column of mine about grasshoppers, several people have described extremely high populations of grasshoppers. It appears we have numerous locations of very high grasshopper populations which have the potential of threatening winter wheat and also be the source of an expanded threat to crops seeded next spring.

If you are in a hot spot for grasshoppers and are thinking about planting winter wheat, be prepared to apply an insecticidal treatment. The current hot and dry conditions are providing very favorable conditions for reproduction of some very hungry grasshoppers. This activity will continue until we receive a good hard frost. Who knows when that will come but records indicate a frost cold enough to kill grasshoppers may not arrive until mid-October.

According to Jan Knodel, NDSU Extension Entomologist, insecticidal seed treatments in winter wheat provide only minimal control of adult grasshoppers. So, if grasshoppers threaten wheat this fall, a foliar insecticide application is the only alternative. Several insecticides are approved for grasshopper control in wheat. A list can be found on pages 110-111 of the 2012 Field Crop Insect Management Guide available from this office or at http://www.ag.ndsu.edu/pubs/plantsci.

Galls On Trees

Are Common

Each year I can count on receiving numerous questions about abnormal growths located on the leaves and sometimes twigs of trees. In the forest industry and academia these growths are referred to as galls.

Galls occur on many species of trees, vary in size and take on a range of forms. They can be large, round bumps, or woody galls; smaller, thin, finer-like projections; red felt-like patches referred to as erineum, and even multicolored hair-covered galls called hedgehog galls.

Galls are really the result of mites and insects feeding on the leaves and stem. When the insects feed they inject growth-altering compounds which stimulate the abnormal growths. The growths can serve as a food source and/or protective structure for various stages of insect development. This eliminates the effectiveness of surface applied insecticides.

Despite the sometimes severe appearance of these galls, they are seldom a threat to the overall tree or shrub health. The reduced beauty of the tree is the major consequence of galls. In cases where gall formation is very heavy and affects more than 30 percent of the leaf area of the entire tree, control of the insects may be warranted. However, controlling mites and insects that form galls on broadleaf trees and shrubs is difficult. An early spring application of a systemic insecticide soil drench may provide effective control. Foliar sprays of a systemic insecticide can provide some level of gall-forming mite and insect control but it will also kill beneficial insects which prey on gall-forming insects. Imidacloprid is an insecticide with systemic meaning it can be taken up by the roots and transferred throughout the vascular system of the tree. It also can be applied to the foliage with some systemic impact.

Horticulture oils can be applied in the spring before bud break and again directly after bud break. However, the timing of application is critical to achieving control. Horticulture oils generally will not harm beneficial insects.

When asked for recommendations, I generally suggest less frequent observation of the tree and to make sure the overall health of the tree is maintained. This usually can be accomplished with adequate water.