PATHOGENICITY AND LIFE CYCLE OF MELOIDOGYNE INCOGNITA AND M. JAVANICA ON LETTUCE (LACTUCA SATIVA L.)

摘要

Inoculum level of 2000 second stage juveniles (J_2) of Meloidogyne incognita and 1000 J_2 of M. javanica per plant were detrimental or pathogenic to lettuce. With an increase in the inoculum levels from 250 to 8000 J_2 per plant, there was a progressive increase in plant growth reduction and total population buildup of both the nematode species. The number of galls per root system also increased with an increase in the inoculum levels. However, the reproduction factor of both the nematodes decreasedwith an increase in the inoculum levels from 250 to 8000 J_2 /plant. Principal symptom associated with root- knot infestation on lettuce is the presence of oblong galls on the root system. Moreover, infected plants failed to produce head. Meloidogyne incognita and M. javanica required 32 and 29 days, respectively to complete their life cycle on lettuce at a temperature ranging between 18-25 deg C.