White grub control application windows are very wide. However, when averaged over insecticide and rate, July applications produce slightly better control than any other month.
Timing of white grub controls
This year’s weather is 180 degrees from last year and grub development is a little later than normal, whereas last year’s development was almost a month ahead of normal. Applications of insecticides for preventive control of white grubs on areas with a history of damage can be applied now through late July or possibly early August when using insecticides like clothianidin (Arena and others), imidacloprid (Merit, Imidicloprid and others) or thiamethoxam (Meridian) . With the newer active ingredient, chlorantraniliprole (Acelepryn), applications should already have been applied. White grub control application windows are very wide. However, when averaged over insecticide and rate, July applications produce slightly better control than any other month. This suggests these insecticides are likely breaking down when applied earlier than July and are slightly less effective on older larvae when applied after July. For curative controls where damage is seen in August or September, trichlorfon (Dylox), will provide the most effective control. Regardless of product, best results ALWAYS are achieved when insecticides are watered in shortly after application. A complete summary of white grub life cycles, ID and control can be found at http://turf.unl.edu/pdfctarticles/maygrubs.pdf
Fred Baxendale, Department of Entomology, firstname.lastname@example.org Zac Reicher, Department of Agronomy and Horticulture, email@example.com, University of Nebraska-Lincoln