During the summers of 2001 and 2002, corn flea beetle populations and Stewart’s wilt assessments were made in four locations in Illinois. Sequential plantings of Jubilee sweet corn, a Stewart’s wilt-susceptible variety, were made every 2 weeks beginning in mid-April and continuing until the end of August. Beetle populations, based on sweep samples, insect counts, and 15-cm yellow sticky traps, along with Stewart’s wilt incidence were recorded weekly. Each week, 90 corn flea beetles were collected from the youngest plots at each site to conduct ELISA tests to determine the portion of the beetle population carrying the Stewart’s wilt bacterium. In 2001, numbers of flea beetles/trap/day reached 100 or more in Champaign, Brownstown, and Dixon Springs by August. Disease incidence reached 22% and 36% in Dixon Springs and Brownstown, respectively, in early summer, fell, and resurged in late August. ELISA tests revealed that the portion of infective beetles fluctuated, ranging from 3 to 67% across all locations. Following a mild 2001-2002 winter, beetles were recorded in April at Dixon Springs, Brownstown, and Champaign. By mid-June, corn flea beetles were found at Mendota. Preliminary results indicate a correlation of between flea beetle numbers when plants are <12” tall and disease prevalence; further data may allow determination of a threshold for foliar spray decisions based on counts of beetles on traps.
Species 1: Coleoptera Chrysomelidae Chaetocnema pulicaria (Corn Flea Beetle)
Keywords: sweet corn, Stewart's wilt
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