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Whitehill: Staying on top of grasshoppers
Published 6/25/2009 in Commentary : Columns
Sometimes, grasshoppers can be so overwhelming and destructive that the only way to deal with them is to poke a little fun at them.
Not every grasshopper is a "bad grasshopper." While a person may note a lot of grasshopper activity when walking along fields or in native grasslands, most have very restricted host ranges and therefore do not constitute a threat to field and garden crops.
Yet, there are several opportunistic species that have a very wide host range and therefore are destructive feeders. Three of the most commonly encountered "garden pests" are the larger two-striped grasshoppers and differential grasshoppers (1.5 inches in length) and the smaller redlegged grasshoppers (approaching only one-inch in length) The adult females of these produce eggpods they deposit in the soil in the fall. The warming of the soil in spring hastens the completion of embryonic development.
Nymphs emerge in mid- to late May. Given their "current" small size, they generally go unnoticed. However, if a person begins noticing small holes appearing in the leaves of various springtime garden crops, closer observations may reveal the presence of the small nymphs — currently only 3/16-1/2 inch in length.
Grasshopper nymphs seem to suddenly appear out of nowhere. Nymphs will consume increasingly greater amounts of foliage as they grow. Therefore, insecticide treatments may be the means with which to address the situation. Various active ingredients (carbaryl, cyfluthrin, esfenvalerate, lambda-cyhalothrin and permethrin) are contained in a wide array of products marketed for use by home gardeners. Visit retail outlets to determine which products are locally available. Make note of (and observe) post-treatment harvest intervals (days after application until it is safe to consume the produce). Due to the relative non-persistence of insecticidal products, additional insecticide applications may be required if there are continued movements of grasshoppers into garden areas.
The popular protozoan Nosema locustae is often promoted as the "organically acceptable approach" for grasshopper control. Marketed (in Kansas) under the tradenames Nolo BaitTM and SemasporeTM, if used under proper circumstances, can be effective.
However, these products were designed for use treating large acreages of rangeland as a long-term control strategy. Comparable results may not be achieved when used as an approach for grasshopper control in home gardens on small scale areas.
White Grubs in Lawns
Masked chafers are the beetles that produce the annual white grubs that are responsible for the grub damage observed in the late summer and fall of the year (usually in late August and September).
For people who routinely apply preventative systemic insecticide applications to their home lawns, now is an appropriate time to apply systemic insecticide treatments. Two Active Ingredients (AI) are incorporated into products for homeowner use: imidacloprid (targets the nervous system) and halofenozide (disrupts the normal molting sequence). Because product manufacturers choose to rename items in their product lines, it is possible that (side-by-side) two packages of a granular product might bear the same trade name, but do not contain the same active ingredient.
Thus, it important to look beyond the trade name and ascertain the actual AI being used (read the fine print!), or ask questions of the garden center employee.
Effective application of either of these products is largely dependent on timing. Each product must be applied, watered in, and allow ample time for the chemicals to be taken up by the grass plant. They are not a quick kill. Application in the next few weeks will allow adequate time for uptake and then provide season-long control of the young grubs and numerous other insects that could potentially cause unsightly large brown out areas later in the summer. In addition, either of these products are much safer and more friendly to the environment.
Other products may be labeled for grubs, but they must be applied, watered into the soil and come in contact with the grubs. They generally work much better when the grubs are very small. As the grub gets larger later in the season, repeated application is required and the grubs become much tougher to kill, thus the advantage of the new chemistries for control.
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