Attraction of Ditylenchus dipsaci and Meloidogyne hapla by Resistant and Susceptible Alfalfa Seedlings.

Ditylenchus dipsaci Kühn were equally attracted to and equally invaded resistant ('Lahontan') and susceptible ('Ranger') germinating alfalfa (Medicago sativa L.) seedlings exposed singly in moist sand except at a distance of 12.5 mm at 20 C when the susceptibles proved more attractive than the resistants. Larvae hatching from egg-masses of Meloidogyne hapla Chitwood were also attracted equally to germinating seedlings of resistant ('M-9') and susceptible ('Lahontan') alfalfa offered singly. When hatched midway between resistant and susceptible, however, more larvae were attracted to the susceptibles. M. hapla larvae were attracted equally to the root and stem apices, region of elongation, and upper hypocotyl of resistant and susceptible plants.