Q: I have several dead spots in my established buffalograss lawn, what might it be?
A: There are many factors that could be negatively affecting your buffalograss lawns, but this time of year is typically when we begin to see presence of chinch bugs. Two chinch bug species may cause concern in Kansas. The common “field” chinch bug, Blissus leucopterus is primarily an agronomic pest associated with wheat, corn, and sorghum. They sometimes migrate out of production fields and infest adjoining cool- or warm-season lawns. The western chinch bug, Blissus occiduus, historically has been associated with wheat, brome, and native grasses. They became popularly known as the buffalograss chinch bug when they emerged as a serious pest in buffalograss lawns. They have a wide host range, including zoysiagrass, perennial rye, and Kentucky bluegrass and fescues.
Chinch bugs cause damage by withdrawing plant sap in the crown area. At the same time, they inject a salivary secretion that injures cells and inhibits the translocation of water and nutrients. Initial yellowing progresses to entire plants taking on a straw-brown appearance. Damage ranges from minor thinning to extreme cases where grass is killed. Chinch bugs can be detected by removing a small section of turf and vigorously shaking it over a sheet of white paper to dislodge the insects. You can also detect chinch bugs by removing both ends from a 2-lb metal coffee can, pressing it firmly into the ground in an area with a suspected chinch bug infestation and filling the can with water. Chinch bugs will float to the surface. If chinch bugs are estimated to exceed 20-25 per square foot (five coffee cans = one square foot) of turf and feeding damage is apparent, control measures are likely to be required. The best defense against chinch bugs are sound cultural practices to keep the turf stand in optimal condition. Since these insects prefer turf areas high in thatch and organic debris, cultural and mowing practices minimizing thatch accumulation should discourage initial infestations and also may help reduce existing chinch bug problems. A second approach for deterring western chinch bug infestations involves planting chinch bug-resistant turfgrasses.
Bifenthrin (Talstar, Ortho Bug-B-Gon), lambda-cyhalothrin (Spectracide Triazicide), or carbaryl (Sevin), applied in 3 to 5 gallons of water per 1,000 square feet, should provide acceptable chinch bug control. Prior to treatment, mow the turf to a height of 1 1/2 to 2 inches and remove the clippings. This will minimize interception of the insecticide by the turf canopy. Immediately following application, irrigate the treated area with 1/8 inch of water to wash the insecticide off grass blades and down into plant crowns and thatch where chinch bugs are feeding. If a granular insecticide is applied, irrigate the turf with at least one-fourth inch of water to activate the insecticide. In areas where chinch bug numbers are very high, two insecticide applications may be required to achieve satisfactory control. Typically, the first treatment should be applied during mid-June and the second in late July.
