Effect of biofumigation and Pochonia chlamydosporia in the management of root-knot nematodes in tomato

The efficiency of different biofumigation treatments, supplemented with the application of Pochonia chlamydosporia for the control of Nacobbus aberrans and Meloidogyne incognita, was evaluated in a greenhouse tomato (cv. Condor) production system. Soil in the greenhouse was naturally infested with the two nematode species with the infestation of N. aberrans greater than that of M. incognita. The four treatments evaluated were: T1. Composted sheep manure and chopped straw + crushed cabbage (Brassica oleracea) + P. chlamydosporia; T2. Cow manure + crushed cabbage + P. chlamydosporia; T3. Chicken manure + crushed cabbage + P. chlamydosporia, and T4. Unamended control. As the growing season progressed, the abundance of second-stage juveniles (J2) of both N aberrans and M incognita in the soil was lower in all amendment treatments than in the control. Since both nematode species induce galling in host plants, the root galling index reflected the aggregate effect of both. Only the T3 treatment significantly reduced nematode infection of the tomato roots. In that treatment, there was a 50% decrease in aggregate galling index, a 68% colonization of nematode egg masses by P. chlamydosporia, and colony 4 x10(7) forming units per gram of tomato root. The gall index for the T1 and T2 treatments was numerically lower (20%) than that of the T4 control, and 63% and 55%, respectively, of the egg masses in those treatments were colonized by the fungus. Fresh and dry weights of the tomato root systems were significantly greater in the control treatment than in the amendment treatments, probably attributable to nematode-induced root galling.