VERTICILLIUM-CHLAMYDOSPORIUM AS A BIOLOGICAL-CONTROL AGENT FOR MELOIDOGYNE-INCOGNITA AND M-HAPLA IN POT AND MICROPLOT TESTS

Verticillium chlamydosporium multiplied in peaty-sand from inoculum rates of 500, 1,000, 5,000 or 10,000 chlamydospores/g soil to a maximum number of 5.5 x 10(4) cfu/g soil and survived for at least 8 wk in pots planted with tomato plants inoculated with 1,000 second stage juveniles of Meloidogyne incognita. The fungus survived, but did not multiply, in loamy sand or sand. Establishment of V. chlamydosporium on the rhizoplane of tomato plants was greater in peaty sand than in loamy sand or sand. Nematode control was in general greater in peaty sand 'average 59% control) than in the other two soil types (average control in loamy sand 51% and in sand 39%). In a microplot experiment on sandy loam, V. chlamydosporium controlled populations of M. hapla on tomato plants by more than 90%. The fungus multiplied and survived in soil for at least 123 days. More fungus was found in rhizosphere soil than in non-rhizosphere soil. Combining V. chlamydosporium with an aldicarb treatment equivalent to 2.8 kg a.i./ha did not affect the activity of the fungus, and gave better control (98%) than a treatment with V. chlamhdosporium or aldicarb alone (90%).