This week, I wanted to share with you all a small excerpt from the Entomology department’s newsletter. I have received a few calls about grub problems in lawns, so I felt that this was important to share.
With Regard to Grub Control in Turf
Based on current recovery of “masked chafer” beetles from blacklight traps, it is timely to address grub control considerations for individuals privately tending their lawns.
“Masked chafers” (of which 6 species have been documented in Kansas) all have similar yearly life cycles. Overwintering in the soil as 3rdinstar (last developmental stage) larvae, grubs complete their feeding requirements during springtime.
Broadly speaking, they pupate in May. While small numbers of “early bird” beetles may appear at the end of May and beginning of June (as well some stragglers appearing through August), earnest flights typically span 4-6 weeks beginning in mid-June through the end of July. Eggs are deposited in the soil with larvae hatching in 2-3 weeks. Larval development is rapid.
Typically by mid-October, in response to cooler soil temperatures, 3rdinstar grubs descend deeper into the soil to overwinter.
For the aforementioned do-it-yourself individuals, there are two tactics when contending with grubs: applying preventative treatments, or, waiting to see the need for curative insecticide applications. The preventative tactic is further divided, and contingent upon the type of insecticide to be used: a long-residual systemic insecticide or short-residual contact insecticide.
Currently, systemic insecticides are those under consideration. After systemic insecticides have been applied, they must be watered into the soil/grub zone (via a timely rain, or an immediate post-treatment irrigation) to assure availability for uptake by grass roots. Thus small grubs(when they emerge from eggs)will be killed when they ingest root tissues and the insecticides contained within. Four active ingredients (chlorantraniliprole, clothianidin, imidacloprid andthiamethoxam) are used in systemic products registered for use as grubicides. Most commonly recognized trade names are Acelepryn, Arena, Merit and Meridian, respectfully. For each of the AI’s, there are 33,26, 412 and 47 products (respectively) registered in Kansas, of which 25, 17, 257 and 24 (respectively) are specifically registered against white grubs. Certain products available for purchase and use by professionals are not available for homeowner purchase/use. The point of listing these numbers is simply to serve as a basis for the inability to answer the specific query, “What product do you recommend that I use to control grubs in my lawn?” Rather, it is incumbent upon the private citizen to investigate what products are locally available for sale to and use by homeowners. All work if proper dosages are applied and watered in.
Alicia Boor is the Agriculture and Natural Resources agent for Barton County K-State Research and Extension. You can contact her by e-mail at aboor@ksu.edu or calling 620-793-1910