COMPARATIVE SUSCEPTIBILITY OF CHRYSANTHEMUM CULTIVARS TO EUROPEAN CORN BORER

Susceptibility between chrysanthemum varieties to the European corn borer, Ostrinia nubilalis (Hubner) was evaluated in both field and laboratory studies. Field studies showed significant differences with the varieties Debonair and West Point being the most heavily infested, and Grenadine, Patriot, Baby Tears, and Revere showing no larval feeding. Laboratory methods utilizing unrooted cuttings yielded inconsistent results. Laboratory screening with the use of stem sections was relatively consistent with Debonair and West Point being the most heavily infested while Revere and Pancho the least infested. A positive correlation between infestation levels and stem diameters indicated stem thickness may be a factor in expression of susceptibility. Debonair and West Point, the most susceptible varieties, had significantly larger stem diameters than the less susceptible varieties, Revere and Pancho.