Pathogenicity and Evaluation of Some Plant Root Extracts on Root-Knot Nematode Infecting Tomato

In the screen house, tomato seedlings, cv. DT 69/257/grown in steam-sterilized soil were inoculated with graded inocula of 5,000, 10,000, 15,000, 20,000 and 25,000 eggs of root-knot nematode, Meloidogyne incognita. At inocula levels of 15,000, 20,000 and 25,000 eggs of M. incognita, number of leaves per plant, plant height, fruit yield and root-galls were significantly reduced. In the field planted with tomato seedlings, aqueous extracts from the roots of marigold, Tagetes erecta nitta (Hyptis suaveolens) and basil (Ocimum gratissimum) plants were applied to root-knot nematode infected soil at four concentrations viz. 25,000; 500,000; 750,000 and 1,000,000 parts per million (ppm.) per tomato plant. All the aqueous plant root extracts reduced the root-knot nematode populations in the soil with corresponding increases in plant height, plant leaf and fruit yield over the untreated control treatment.