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Bermudagrass Stem Maggots

Dr. Dennis Hancock, UGA Extension Forage Crops Specialist, has sent word that bermudagrass stem maggot damage is beginning to show up across the southern part of the state as far north as Laurens County. These pests can be a major problem for our hay producers if populations are high enough. One of the first signs of the presence of BSM is a yellowing/bronzing of the uppermost two or three leaves of the bermudagrass. It will be somewhat similar to frost damage. If you were to examine the plant, you would likely see where the BSM has fed at the top node which caused the decay of the top few leaves.

Generally the best time to apply insecticides for BSM is 7-10 days after the last cutting. If the grass is still not responding, then a sequential application in another 10 days is an option. As of now, various pyrethroids are recommended for BSM such as lambda-cyhalothrin (Warrior/Karate), cyfluthrin (Baythroid), zeta-cypermethrin (Mustang Maxx), and others. It is important to get sufficient canopy penetration, so applications with a water volume of 12-15 GPA will likely yield better control. However, it is not always economical to spray for BSM. Usually we do not spray before our first cutting or cuttings in the fall because our yield loss from BSM will not be enough to cover our insecticide costs.

If you observe damage from BSM, please let me know so I can relay the information.