Distribution and identification of root-knot nematode species in tomato fields

The survey conducted to assess the incidence of root-knot disease on tomato in 8 localities in and around Aligarh (India) showed that the crops of tomato in all the 8 localities were infected with root-knot nematodes. Highest frequency (90%) was found in Idgah area, closely followed by Shah Jamal and Mathura Road localities. In both the localities the frequency was 80%. In Delhi Road and Agra Road areas the frequency of the disease was 60% and 70% respectively. The frequency in Ramghat Road area was 50%. The lowest frequency (40%) was found in Kasimpur Road and University Farm areas. Both gall index and eggmass index (average) ranged between 2-5 through 3 and 4. The greatest eggmass and gall indicates (5 each) was found in Idgah area, the area in which the incidence was also greatest. The gall and eggmasses indices were 4 in Shah Jamal Delhi Road, Mathura Road and Ramghat Road areas. In Agra Road and university Farm areas the indices were 3 each. The lowest incidences (2 each) were noticed for Kasimpur Road area. Thus, the intensity of the disease on tomato was highest in Idgah closely followed by Shah Jamal, Delhi Road, Mathura Road and Ramghat Road areas in descending order. In other three localities (Agra Road, University Farm, Kasimpur Road) the intensity of the disease was comparatively low. Meloidogyne incognita and M. javanica, were identified to infect tomato in different areas. The species were either found singly or in mixed populations. Out of the two, M. javanica was more frequent. It was found in 7 localities out of 8 either singly or in concomitantly with M. incognita. In three areas (Agra Road, Mathura Road and Ramghat road) it was encountered alone but in other four areas it was present together with M. incognita. It was present in all the localities except Delhi Road area.