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Title: THE USE OF MELALEUCA OIL FOR CROP DISEASE CONTROL.

Author
item Caolo Tanski, Janet
item Hanson, Linda
item Hill, Amy
item HILL, JOSEPH - COLORADO STATE UNIVERSITY
item SCHWARTZ, HOWARD - COLORADO STATE UNIVERSITY

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/22/2003
Publication Date: 6/1/2004
Citation: Caolo Tanski, J.M., Hanson, L.E., Hill, A.L., Hill, J.P., Schwartz, H.F. 2004. The use of melaleuca oil for crop disease control. Phytopathology. 94:S150

Interpretive Summary: Melaleuca alternifolia oil (Mo) has been used widely as an antiseptic. The anti-microbial activity of Mo was tested in vitro against seven fungal and two oomycetous plant pathogens. Different volumes of Mo were applied as equal aliquots on four 10 mm diameter filter paper disks set equidistant on 30 ml Potato Dextrose Agar plates, followed by centrally placing a 3 mm mycelial plug per plate. Growth of Pythium and Phytophthora was completely inhibited at 20 and 60 'l, respectively. Four fungi had no growth at 60 'l and all but one had no growth at 100 'l. Sugarbeet and potato were used to determine the efficacy of Mo for disease control in field plots. Leaves were treated for foliar pathogens and crowns (sugarbeet) for soil-borne pathogens. No significant differences were found (P > 0.05). In greenhouse tests, sunflower treated with Mo had significantly (P < 0.02) higher white mold ratings than the untreated check (perhaps due to phytotoxicity). Mo inhibited plant pathogen growth, however further research is needed to determine if Mo can reduce disease severity.

Technical Abstract: Melaleuca alternifolia oil (Mo) has been used widely as an antiseptic. The anti-microbial activity of Mo was tested in vitro against seven fungal and two oomycetous plant pathogens. Different volumes of Mo were applied as equal aliquots on four 10 mm diameter filter paper disks set equidistant on 30 ml Potato Dextrose Agar plates, followed by centrally placing a 3 mm mycelial plug per plate. Growth of Pythium and Phytophthora was completely inhibited at 20 and 60 'l, respectively. Four fungi had no growth at 60 'l and all but one had no growth at 100 'l. Sugarbeet and potato were used to determine the efficacy of Mo for disease control in field plots. Leaves were treated for foliar pathogens and crowns (sugarbeet) for soil-borne pathogens. No significant differences were found (P > 0.05). In greenhouse tests, sunflower treated with Mo had significantly (P < 0.02) higher white mold ratings than the untreated check (perhaps due to phytotoxicity). Mo inhibited plant pathogen growth, however further research is needed to determine if Mo can reduce disease severity.