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Monday, November 2, 2009
Convention Center, Exhibit Hall BC, Second Floor
Abstract:
Abstract:
The meals (co-products remaining after oil extraction) from many oilseed crops contain toxic chemicals that are known to inhibit the growth and activity of some soil microorganisms including several plant pathogens. The fungus Phymatotrichopsis omnivora is the causal agent of cotton root rot and has greatly hindered the production of cotton and alfalfa in Texas and the southwestern USA. We investigated the effect of oilseed meals from both Brassicaceous plants including Brassica juncea, Brassica camelina, and Brassica napus as well as non- Brassicaceous plants including Jatropha curcas, Linum usitatissimum (flax), and Triadica sebifera (Chinese tallow) on P. omnivora sclerotial germination and hyphal growth in Branyon clay soil. The oilseed meals were amended to the soil at rates of 0%, 1%, and 5% (w/w). B. juncea seed meal completely inhibited sclerotial germination at both 1% and 5%. B. camelina, B. napus, and J. curcas seed meals showed decreased sclerotial germination at the 5% application rate. Neither flax nor Chinese tallow showed any inhibiting effects on sclerotial germination. All tested Brassicaceae seed meals including B. juncea, B. napus, and B. camelina and one non- Brassicaceae (J. curcas) seed meal were found to prevent active fungal mycelial growth at as low as a 1% application rate. These results indicate that several Brassicaceous species as well as a non-Brassicaceous species can inhibit Phymatotrichopsis omnivora sclerotial germination and active mycelial growth and thus may have potential for controlling cotton root rot.
The meals (co-products remaining after oil extraction) from many oilseed crops contain toxic chemicals that are known to inhibit the growth and activity of some soil microorganisms including several plant pathogens. The fungus Phymatotrichopsis omnivora is the causal agent of cotton root rot and has greatly hindered the production of cotton and alfalfa in Texas and the southwestern USA. We investigated the effect of oilseed meals from both Brassicaceous plants including Brassica juncea, Brassica camelina, and Brassica napus as well as non- Brassicaceous plants including Jatropha curcas, Linum usitatissimum (flax), and Triadica sebifera (Chinese tallow) on P. omnivora sclerotial germination and hyphal growth in Branyon clay soil. The oilseed meals were amended to the soil at rates of 0%, 1%, and 5% (w/w). B. juncea seed meal completely inhibited sclerotial germination at both 1% and 5%. B. camelina, B. napus, and J. curcas seed meals showed decreased sclerotial germination at the 5% application rate. Neither flax nor Chinese tallow showed any inhibiting effects on sclerotial germination. All tested Brassicaceae seed meals including B. juncea, B. napus, and B. camelina and one non- Brassicaceae (J. curcas) seed meal were found to prevent active fungal mycelial growth at as low as a 1% application rate. These results indicate that several Brassicaceous species as well as a non-Brassicaceous species can inhibit Phymatotrichopsis omnivora sclerotial germination and active mycelial growth and thus may have potential for controlling cotton root rot.