Total Landscape Care Digital Magazine
Issue link: http://read.dmtmag.com/i/251533
chemical care Checking for chinch bugs Confirming a chinch bug population in turf is easier said than done, as chinch bug damage can be confused with that of other insect pests and some diseases, as well as dehydration. Damage in St. Augustine first presents itself as yellow or brown- ish spots. "Damage may occur in open, sunny areas near sidewalks and driveways but also in the middle of lawns," Buss says. "Infested plants have slower growth, turn yellow, then rusty reddish-brown and die. The damage is often confused with drought or frost stress." To confirm the cause, look for chinch bugs between the thatch and soil of a yellowed area. Adults are 1/5-inch long and have black bodies and white wings. Buss says another option is to use a Dust Buster or handheld vacuum to suck up any bugs near damaged areas. Empty the contents to find nymphs or adult chinch bugs. Hard to resist Outside of Florida, chinch bug resistance to insec- ticides isn't all that common. So if you are us- ing a product labeled to control them and it isn't doing the job, resistance should not be your first consideration. "It is important to understand that other than a few populations in Florida, most populations in other states are not known to be resistant to some of the most commonly used insecticides, such as bifenthrin (Talstar and others)," says Juang Horng Chong, Ph. D, assistant professor of entomology at Clemson University. "I would not assume resis- tance is the main factor when there is a difficult- to-control population outside of Florida." Instead, Chong recommends considering how you're applying the product. In fact, he says most of the issues related to poor control of southern chinch bugs stems from poor application and penetration. "It's important to use either high-volume spray (2 to 5 gallons per 1,000 square feet) or watering- in after application to drive the insecticides down to the thatch layer where the chinch bugs are feeding and hiding," Chong says. "Dethatching before the application also helps. Following good preparation and application precautions, even an often-used insecticide, such as bifenthrin, can be effective." If you're working on a lawn that has been treated with a single insecticidal active ingredient during multiple years and aren't getting results — and are confident in your application method — Chong recommends contacting your state extension personnel for help in determining if resistance is indeed an issue. Fighting the resistance "If resistance is indeed an issue, then the use of all the insecticides belonging to the affected chemical class or mode of action must be stopped," Chong says. "To delay resistance development and de- velop a program after the resistance is confirmed, use insecticides of different modes of action." The Insecticide Resistance Action Committee (IRAC) has developed a coding system to make the determination of the mode of action easy for everyone. Many insecticide manufacturers have ad- opted this code and include it prominently on their chemical label (usually above or close to the brand name of the product), Chong explains. Within this system, each mode of action is assigned a number. To rotate modes of action, you would rotate products that have different numbers. "It is important to remember that insecticides 12 To t a l L a n d s c a p e C a r e . c o m F E B R U A R Y 2 014 PHOTO COURTESY OF DAVID SHETLAR, THE OHIO STATE UNIVERSITY, BUGWOOD.ORG Typical damage by southern chinch bugs on a home lawn is patchy and often confused with drought or frost stress.