Nematicidial Activity of Five Cruciferous Seed Extracts in Controlling the Root-Knot Nematode Infecting Cucumber Plants

A greenhouse experiment was conducted to evaluate the effectiveness of five plant aqueous extracts of watercress, radish, turnip, cauliflower, and cabbage, either as seed extract or geminated seed extract, compared with oxamyl nematicide to protect cucumber plants from infection with the root knot nematode Meloidogyne incognita. In general, all the tested aqueous plant extracts and the chemical nematicide led to a significant decrease in the number of nematode root galls, egg masses, and eggs per gram of root as well as the number of larvae per 250 g of soil compared to the untreated inoculated control. The aqueous extracts of the germinated cauliflower seed and watercress seed had the highest nematicidal effect against root gall formation, egg-masses, and the number of eggs per gram of root. The cauliflower seed extract had the maximum nematicidal effect against nematode juveniles in soil, whereas the radish seed extract has turned the least effective. The tested aqueous plant extracts significantly increased the shoot’s fresh weight compared to the untreated inoculated control. Soil drenching with the germinated cruciferous seed extracts exhibited similar activity against M. incognita in terms of a significant increase in ascorbic acid, salicylic acid, and phenol content. Keywords: Plant extracts, nematicidal activity, Meloidogyne incognita, cucumber.