HYG  Pest newsletter

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White Grubs

September 28, 2005

Reports of white grubs this fall have been few and far between. Expect damage to continue into the fall, most likely in small, “hot spot” areas consisting of portions of lawns or of a few lawns in a neighborhood. Nonirrigated lawns are unlikely to have many white grubs for two reasons: (1) Their dormant grass in July would have been less attractive to the beetles for egg-laying. (2) Insufficient rainfall has probably occurred this fall for the grubs to survive, particularly Japanese beetle.

Trichlorfon (Dylox) is likely to be most effective at this time of year and kills the grubs within about 3 days. Treatment is effective as long as the grubs are in the root zone. Japanese beetle grubs will be there until the soil temperature drops below 60°F; masked chafers, annual white grubs, will be in the root zone until the temperature drops below 50°F. An easy way to tell whether you can still treat the grubs is to pull back the sod. If the grubs are still present in the root zone, then treatment should be effective.