Fusarium crown-rot development in alfalfa stressed by threecornered alfalfa hopper (Homoptera: Membracidae) feeding

Alfalfa, Medicago sativa L., plants were inoculated with Fusarium oxysporum Schlecht, and infested with Spissistilus festinus (Say) nymphal populations for six harvest periods under greenhouse conditions. Significant interactions between insect populations and F. oxysporum were found for number of harvestable stems and percent acid detergent fiber. The main effect of inoculation did not significantly affect any of the plant parameters examined. Insect populations, however, reduced plant height, root carbohydrate concentration, forage yield, and forage quality. S. festinus nymphs also were found to cause a significant increase in Fusarium crown-rot severity after six harvest periods