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Title: REDISCOVERY OF THE SOUTHERN CORNSTALK BORER: A POTENTIALLY SERIOUS PEST OF EASTERN GAMAGRASS AND STRATEGIES FOR MITIGATION

Author
item Krizek, Donald
item Solis, M Alma
item Touhey, Peter
item Ritchie, Jerry
item Millner, Patricia

Submitted to: Eastern Native Grass Symposium
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2003
Publication Date: 10/21/2004
Citation: Krizek, D.T., Solis, M.A., Touhey, P.A., Ritchie, J.C., Millner, P.D. 2004. Rediscovery of the southern cornstalk borer: a potentially serious pest of eastern gamagrass and strategies for mitigation. In: Randall and J.C. Burns, (eds) Proceedings of the Eastern Native Grass Symposium. North Carolina Botanical Garden, Chapel Hill, NC, Oct. 1-3, 2002, Omnipress, Madison, WI. p. 277-283.

Interpretive Summary: Eastern gamagrass is a native, perennial, warm-season grass that has attracted considerable interest because of its many desirable features as a forage crop and as a grass hedge. It is considered relatively free of insect pests and plant diseases. Plots of eastern gamagrass were grown successfully at the Beltsville Agricultural Research Center for several years without noticeable damage from insects or plant pathogens. However, in June 2001, random patches of eastern gamagrass showed mysterious dieback within two weeks after harvesting the plants for determination of biomass and forage quality. Upon close inspection, small caterpillars were found emerging from the base of the stalks. Microscopic examination of these caterpillars revealed the presence of both cut worm and snout moth larvae. Although adult moths were never observed, the snout moth larvae were identified as those of the southern cornstalk borer. This pest feeds upon corn, grain sorghum, Johnson grass, and eastern gamagrass and can cause serious crop damage. This pest is widely distributed from Delaware/Maryland to Florida. This is the first report of this pest in the Mid-Atlantic region since it was discovered in 1891. Farmers should be aware of this pest because it is highly destructive. Removal of plant debris at the end of the season is the main way of preventing infestation.

Technical Abstract: Eastern gamagrass [Tripsacum dactyloides (L.) L] is considered relatively free of insect pests and plant pathogens. Plots of eastern gamagrass at the Beltsville Agricultural Research Center in Beltsville, MD were grown successfully for five years without noticeable damage from insects or plant pathogens. However, in June 2001, random patches of eastern gamagrass showed mysterious dieback within two weeks after harvesting the plants for biomass and forage quality analyses. Upon close inspection, larvae were found emerging from the crown tissue. Microscopic examination of the larvae revealed the presence of both noctuid and pyraloid larvae. Although adult moths were never observed, the pyraloid larvae were identified as the southern cornstalk borer [Diatraea crambidoides (Grote), Crambidae: Crambinae, LEPIDOPTERA]. This pest feeds upon corn, grain sorghum, Johnson grass, and eastern gamagrass. A literature search revealed that this pest occurs from Delaware/Maryland to Florida and in inland states (KS, OH, OK, MS, and AZ) through Mexico and northern South America but it has not been reported in its northern most distribution since 1891. Farmers should be aware of this pest because it is highly destructive. Various strategies for mitigating damage from this pest are discussed.