Tomato culture filtrate stimulates hatching and activity of Meloidogyne incognita juveniles

Hydroponic culture media were tested after growing tomato, okra, cucumber and bean for their effect on hatching and mobility of Meloidogyne incognita second-stage juveniles (J2) in laboratory experiments. Tomato and okra culture media increased the numbers of J2 that hatched as compared to those in water or fresh culture medium. The tomato culture medium increased hatching even in the presence of fosthiazate, an organophosphate nematicide, and at a concentration that inhibited hatching in the absence of tomato culture medium. Neither heat treatment of the tomato culture medium nor change of pH abolished its hatching stimulatory activity. When active J2 were incubated in the tomato culture media, the percentages of nematodes that became quiescent were lower than those of nematodes incubated in water or in fresh culture medium for 3 and 7 days in two trials. Moreover, the sigmoid movement of J2 was faster in the tomato culture medium than in water. Quiescent J2 became active more rapidly in culture media of tomato, cucumber and okra than in water or fresh culture medium. In experiments using soil containing quiescent J2, more J2 were extracted with the Baermann funnel method from soil treated with tomato culture medium than from soil treated with water. The results confirm that nematode stimulants, which may serve as a potential means in nematode control, exist in the plant culture media.