Hay growers in parts of Mississippi may see signs of bermudagrass stem maggot in their stands, warns Rocky Lemus, forage specialist with Mississippi State University Extension.

“So far this year, we’ve had reports of the pest in eight different locations in the southern and central parts of the state,” says Lemus. “At this point, the areas are distant from each other. So producers in other places might not be aware yet that they have an issue.”

A south-Asian native, the stem maggot was first discovered in North America in three Georgia counties during 2010. Since then, the pest has been found in several other Southeastern states. In Mississippi, it was first discovered last year, Lemus says.

University of Georgia researchers say stem-maggot-infested bermudagrass fields often look frost-damaged in the middle of the growing season. The insects cause damage during their larval (maggot) stage. The adult fly lays its eggs on folded leaf blades. When the larva hatches, it works its way toward a node. As the larva develops, it feeds on the node, causing the last few leaf blades on the plant to turn brown.

Lemus says no one knows for sure how the pest has spread within the region. “One theory is that it might move from place to place when hay is transported,” he says. “Others believe it might be moved around by hurricane winds.”

First-year infestations can reduce production by 20-40%, Lemus notes. “If fields aren’t treated, the damage can be more extensive in the second year.”

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Options for treating with insecticides are limited. “Systemic pesticides aren’t labeled for use on hay or forage crops. In Georgia, producers and researchers report that they’ve had some success using pyrethroid insecticides like Karote or Mustang Max.”

Producers should check with their state Extension offices or ag departments to see if there are haying or grazing restrictions before using those products, however.

For more information, check out Biology and Management of Bermudagrass Stem Maggot, a fact sheet developed by forage and entomology specialists at University of Georgia and Alabama Cooperative Extension System. Two YouTube videos on the stem borer can be found at:http://www.youtube.com/watch?v=mXwyl4g0A6Uandhttp://www.youtube.com/watch?v=fx03UMYJiVI.

To contact Lemus, call 662-325-7718 or email rlemus@ext.msstate.edu.

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