Commercial varieties of glandular-haired (GH) alfalfa have been marketed as having resistance to the potato leafhopper (Empoásca fŕbae (Harris)). Field studies were initiated in 1999 to evaluate the role of GH alfalfa under established alfalfa pest management practices. Pioneer ‘54H69’, a second-generation GH cultivar, and Southern States ‘Choice’, a standard alfalfa cultivar, were seeded in the southwestern and Piedmont regions of Virginia. Large plots (0.1 acre) (n=16) were planted in a randomized complete block design with four combinations of insecticide-treated and untreated ‘54H69’ and ‘Choice’ cultivars. Treated plots received one insecticide application for alfalfa weevil (Hypera postica (Gyllenhal)) and one application for E. fŕbae. Populations of E. fŕbae were assessed using a sweep net. In addition, yield and forage quality parameters of both cultivars at each site were compared. Overall, ‘54H69’ did not appear to offer any distinct advantages over ‘Choice.’ Except for a significantly greater density of nymphs found in ‘Choice’ at the southwestern location in 2000, no significant differences in adult, nymphal, or total E. fŕbae populations were detected between cultivars at either location in 2000 or 2001. Both cultivars produced similar total dry yields at both locations in 2000, and at the Piedmont location in 2001. Not surprisingly, insecticide treatment typically reduced pest populations for 2-3 weeks after treatment. However, application of an insecticide did not always provide a clear advantage in terms of increased yield or forage quality. Data from the current 2002 field season will be included in this poster display.
Species 1: Homoptera Cicadellidae Empoasca fabae (potato leafhopper)
Keywords: glandular-haired alfalfa, leafhopper-resistant
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