EFFECT OF FORMULATED BOTANICAL EXTRACTS IN COMBINATION WITH BIOLOGICAL CONTROL ORGANISMS AS AN INTEGRATED STRATEGY TO CONTROL FUSARIUM WILT

Authors: Bowers, John; Locke, James

Submitted to: Biological and Cultural Tests for Control of Plant Diseases
Publication Type: Other
Publication Acceptance Date: 12/28/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Greenhouse tests were conducted to evaluate the use of formulated plant extracts and essential oils in combination with biocontrol organisms to control Fusarium wilt of muskmelon. Treatments included formulated plant extracts and essential oils and biocontrol organisms, either alone or in combination. The extract treatments consisted of either a pepper/mustard mixture (formulated chili pepper extract and essential oil of mustard mixture or cassia (formulated extract of cassia tree) in separate experiments. The biocontrol organisms were Gliocladium virens GL-21 (SoilGard 12G), Trichoderma harzianum KRL-AG2 (RootShield), Trichoderma sp. 5c (isolated from soil treated with Insect Control Concentrate), and nonpathogenic F. oxysporum strain CS-20. The proportion of symptomless plants was recorded for each extract, biocontrol, and combination and expressed in terms of the proportion of diseased plants based on the number of plants at emergence. Over all trials, there was no significant difference between the biocontrol organisms by themselves and the untreated control on disease development. A 10% aqueous emulsion of the cassia extract was effective in suppressing disease development by itself, and there was no significant difference with the addition of the biocontrol organisms. Two pepper/mustard mixtures only partially controlled disease development, and the addition of the biocontrol organisms did not significantly reduce disease further, with the exception of CS-20, which further reduced disease development when added to soil compared to the extract treatments by themselves. This demonstrates the principle that combining a natural plant extract and biocontrol organism may be a viable strategy to control soilborne pathogens.

Technical Abstract: Greenhouse tests were conducted to evaluate the use of formulated plant extracts and essential oils in combination with biocontrol organisms to control Fusarium wilt of muskmelon. Treatments included formulated plant extracts and essential oils and biocontrol organisms, either alone or in combination. The extract treatments consisted of either a pepper/mustard mixture (formulated chili pepper extract and essential oil of mustard mixture or cassia (formulated extract of cassia tree) in separate experiments. The biocontrol organisms were Gliocladium virens GL-21 (SoilGard 12G), Trichoderma harzianum KRL-AG2 (RootShield), Trichoderma sp. 5c (isolated from soil treated with Insect Control Concentrate), and nonpathogenic F. oxysporum strain CS-20. The proportion of symptomless plants was recorded for each extract, biocontrol, and combination and expressed in terms of the proportion of diseased plants based on the number of plants at emergence. Over all trials, there was no significant difference between the biocontrol organisms by themselves and the untreated control on disease development. A 10% aqueous emulsion of the cassia extract was effective in suppressing disease development by itself, and there was no significant difference with the addition of the biocontrol organisms. Two pepper/mustard mixtures only partially controlled disease development, and the addition of the biocontrol organisms did not significantly reduce disease further, with the exception of CS-20, which further reduced disease development when added to soil compared to the extract treatments by themselves. This demonstrates the principle that combining a natural plant extract and biocontrol organism may be a viable strategy to control soilborne pathogens.