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United States Department of Agriculture

Agricultural Research Service

Title: Efficacy of the Fungus Verticillium Lecanii for Suppression of Root-Knot Nematode Egg Numbers on Cantaloupe Roots

Author
item Meyer, Susan

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 22, 1999
Publication Date: N/A

Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack plants and cause seven billion dollars of agricultural losses annually in the United States. Cantaloupe does not have high levels of resistance to these plant pests. Consequently, it is important to enhance strategies for reducing yield losses caused by nematodes attacking cantaloupe roots. Two strains of the potential biocontrol fungus Verticillium lecanii were applied near roots of cantaloupe plants in soil treated with root-knot nematode. The nematode was applied at two levels: 1000 and 5000 eggs per pot. Plants were grown for 55 days in the greenhouse, and then harvested and checked for vigor and for nematode egg production. At the 1000 egg level, neither fungus strain affected nematode population numbers. At the 5000 egg level, both strains of the fungus decreased egg numbers (reductions were 28% and 32% compared to water controls). Neither strain affected number of eggs embedded in root galls; the fungus decreased nematode population numbers affecting eggs outside the roots. Both fungus strains were also applied after being heat-killed. Application of one dead fungus strain resulted in a 35% reduction in egg numbers, suggesting that the fungus produced a substance harmful to the nematode eggs. The results will be used by scientists developing environmentally safe methods for managing nematodes that attack plants.

Technical Abstract: Two strains of the fungus Verticillium lecanii were applied in a wettable granule formulation near roots of cantaloupe plants in soil treated with Meloidogyne incognita. The nematode was applied at two levels: 1000 and 5000 eggs per pot. Plants were grown for 55 days in the greenhouse, and then harvested and checked for vigor and for nematode egg production. At the 1000 egg level, neither fungus strain affected nematode population numbers. At the 5000 egg level, both strains of the fungus decreased egg numbers (reductions were 28% and 32% compared to water controls). Neither strain affected number of eggs embedded in root galls; the fungus decreased nematode population numbers overall solely by affecting eggs in the rhizosphere. Both fungus strains were also applied after autoclaving to test for effects of nonviable fungus. Application of one autoclaved strain resulted in a 35% reduction in egg numbers, suggesting that the fungus produced a heat-stable substance deleterious to the eggs.

Last Modified: 11/26/2014
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