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Home Publications Seed and Seedling Diseases in the Western US Comparing Three Methods of Assaying Soil Fusarium an dTrichoderma Populations for Integrated Pest Management in Forest Nurseries

Comparing Three Methods of Assaying Soil Fusarium an dTrichoderma Populations for Integrated Pest Management in Forest Nurseries

Three methods for assaying soil populations of potentially pathogenic Fusarium spp. and potentially antagonistic Trichoderma spp. were compared at the USDA Forest Service Lucky Peak Nursery near Boise, Idaho. Standard soil dilutions and estimates of colonization of residual roots within soil and roots from healthy-appearing seedlings were compared at the end of the first growing season of 1-0 ponderosa pine. Tested areas had undergone four different pre-plant treatments (methyl bromide/chloropicrin fumigation, fallowing with periodic cultivation, and incorporation of two different Brassica green manure crops). The three assay methods were similar in their ability to estimate treatment effects on soil populations of both Fusarium and Trichoderma. However, all three methods did not give adequate predictions of disease potential because they estimated overall Fusarium populations instead of elaborating pathogenic isolates. Improved assay methods for implementing integrated pest management should include molecular markers for pathogenic strains of Fusarium to supplement soil and seedling root colonization assays.


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Author(s): USDA Forest Service

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