SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
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time where the mixture is applied. Complete coverage of the treated plant is essential. There should be no cross-resistance between the toxins. In effect, both compounds should each be able to kill the target pest, which is called "redundant killing." As turfgrass managers, we are not chemists, and we don't know if only one of the compounds in the mix is doing all the heavy lifting or if there is really a benefit to having both compounds in the mix. Whether or not mixtures are useful in pesticide resistance management is controversial among applicators, researchers and regulators. Some say that the use of mixtures in resistance management is not supported by either computer models or field experiments, although lab tests can make mixtures appear to work. It is possible that a mixture could incompletely kill multiple life stages of a pest, instead of killing everything it was intended to kill. That means that some bugs still survive, lay eggs and pass on their resistance genes to the next generation. I asked someone at that meeting if they thought it might be possible to restore the use of a product when resistance levels were really www.stma.org high (like bifenthrin and chinch bugs in parts of Florida), and they pessimistically said that it was too late. I hope that's not true. They also said that resistance management should start before field failures occur. So the time is NOW to determine how to delay resistance development in the neonicotinoids like Arena (clothianidin), Meridian (thiamethoxam) and Merit (imidacloprid). RESISTANCE MANAGEMENT STRATEGY Okay, so I also had the question of what a resistance management strategy should look like. Should each pest generation only be exposed to one active ingredient? Should all of a species' populations be treated with the same compound at the same time, or should each infested site be treated differently? In lawn care, that is what we do—each lawn is treated differently often by different companies, thereby creating a "mosaic" effect, unless a whole neighborhood is under the management of one pest management company. If property 1 is treated with bifenthrin (Talstar) and neighboring property 2 is treated with clothianidin (Arena), then what happens next? Any surviving insects on either property may find each other, mate and have offspring that can better survive an application of either compound applied alone or mixed together. Almost sounds like a cliff-hanger; we can't predict how fast resistance will develop to another compound in this common type of scenario. So, what does this all mean? Be good product stewards and help us develop a functional resistance management plan for turf. Implement integrated pest management or IPM. Avoid treating turfgrass unless you absolutely have to, which admittedly challenging for a route-based business. Just because you treat green grass and it stays green after an application does not mean that a product worked—it may mean that no pests were present and causing damage at the time of application. Overuse of products like this is one route to developing product failures down the road. ■ Dr. Eileen Buss is an associate professor, Entomology & Nematology Dept., University of Florida. This article first appeared in the Florida Turf Digest's July/August 2012 issue. SportsTurf 21