Golf Course Management

AUG 2014

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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38 GOLF COURSE MANAGEMENT 08.14 Winning the mosquito war with Bt Twilight. The best time of day to play golf. The air is cool, the wind is calm and the sun is mellow. Friends leave work and meet for a leisurely nine. Tag-along kids like to work the ball washer and rake out bunker footprints. The sun sets a little lower and then a tiny sound like razors across an overtuned violin threatens to cut the evening short. One swat, then a slap and splat, and eventually the evening belongs to the mosquito. Mosquitoes can become a threat to rev - enue as well as to the health of humans, do- mestic animals and wildlife. So why is it so hard to control a wisp of an insect no bigger than a dandelion seed? Sheer numbers are on their side. However, it also may be due to the fact that this pest goes unnoticed until the adult stage. Synthetic pesticides used to control adult and larva are generally nonselective and, as such, can negatively impact benefcial in - sects. Effective biological control can be a less lethal alternative to achieve control early in the mosquito's lifespan. Bacillus t ingienisis (Bt) is a biological control that acts upon the mosquito larva be - fore becoming an adult. The mosquito un- dergoes complete metamorphosis: egg, pupa, larva and adult. During the larva stage, the mosquito feeds and lives in water. It is only during this larva stage that the mosquito is susceptible to Bt control. The Bt bacteria para - lyze the digestive system of the larva and effec- tively starve it to death (Cranshaw, W.S. 2008. Colorado State University Extension, Bacillus t ingienisis Fact Sheet No. 5.556, www.ext. colostate.edu/pubs/insect/0556.pdf ). Bt is not a silver bullet. The same principles of turf pest management must be applied to achieve mosquito control. Understanding the biology and habitat of the mosquito is essential to developing a multi-pronged control strategy. The superintendent must monitor pest levels and properly time Bt applications. Developing an integrated pest management approach en - ables the manager to achieve success with bio- logical controls. Eliminate mosquit abitat. The most basic management strategy is to identify and elimi - nate stagnant water and overgrown vegetation. Mosquitoes lay eggs in stagnant and slow-mov - ing water. They thrive in areas where exces- sive vegetation provides moisture and cover from predators. Mosquito larvae live in aban - doned tires, poorly drained ditches, potholes, plugged drains, water-holding bunkers, etc. Be certain that no areas are regulated as wetlands. Do not drain wetlands. Mosquito biology. Mosquito life cycles can vary due to climate and species. Check with a local Extension offce to gain a clearer un - derstanding of species life span in your area. Generally, adults can live up to 14 days. The larva stage spans about seven to 14 days. Some mosquito species are daytime biters and some bite only at night. Daytime biters can come from several miles while nighttime biters are from shorter distances (Biological Notes on Mosquitoes, www.mosquitoes.org/Life - Cycle.html ). Check with an entomologist for identifcation if adults are present while your monitoring of nearby water bodies indicates no larvae activity. Pamela C. Smith, CGCS Greenskeeper99@yahoo.com Monitoring and timing. Bt applications need to be done during the larva stage. If stagnant waters cannot be drained, weekly monitor - ing should begin in spring. A white dipper is used to remove about a cup of water. Inspect the water for the dark-colored wiggler larvae. If no larvae are present, check the label to see if preventive applications are allowed. When lar - vae are present, treat according to label recom- mendations. Check for larvae after rain events in addition to weekly monitoring. Rain events can move Bt-treated waters, leaving an area ripe for new larvae. To test Bt effcacy, place a few grains of product in a container with stagnant water and several larvae. Larvae should expire within one to three days of being exposed to Bt. Read t e label, record and report. There are several commercially available Bt pesticides. Bt products can be granular or in the form of dunks (little pucks). Bt products are labeled as pesticides and should be treated as such. Read the label and apply only according to label di - rections. Check the local, state and federal ap- plication and reporting requirements prior to using any pesticide on or near a body of water. Some application sites may require a permit to apply to waters regulated by private and gov - ernmental agencies. Bt biological control can be an effective control of mosquito pests. However, Bt use re - quires diligent monitoring and understanding of mosquito biology and habitat. Proper use of Bt can eliminate the reliance on nonselective synthetic pesticides and, in turn, protect bene - fcial organisms essential to a balanced ecology. Pamela C. Smith, CGCS, is the director of agronomy for a large city and a 23-year member of GCSAA. Bacillus thuringienisis (Bt) products for controlling mosquitoes come in several forms, including little pucks. Photo by Pamela Smith Presented in Partnership with Aquatrols (environment)

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