Role of Plant Quarantine in Checking Dispersal of Nematodes with True Seed

Unknowingly man has helped, to agreat extent, in the worldwide geographical distribution of several economically important plant parasitic nematodes through the exchange of nematode infested/contaminated plant material. With the growing awareness of the role of nematodes as a limiting factor in agricultural production, testing of seed material for nematode infestation is now being undertaken by many seed health testing and quarantine laboratories. Nematodes could be transported with the true seeds, either as internally seed-borne or as a contaminant with seed in the form of nematode galls, infested plant debris, soil clods, soil entangled between corrugated seed surface etc. Important nematode interceptions made while quarantine processing of true seed material during 1976–1986 period included Aphelenchoids besseyi, Rhadinaphelenchus cocophilus, Ditylenchus dipsaci, D. angustus, Anguina tritiei, Heteroderaschachtii, H. humuli. Some of the nematode species intercepted are still not recorded from India and are known to cause extensive damage to crops in country of origin.