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United States Department of Agriculture

Agricultural Research Service

Title: Variability Associated with Suppression of Gray Mold (Botrytis cinerea) on Geranium (Pelargonium x hortorum) by Foliar Applications of Non-Aerated and Aerated Compost Teas

Authors
item Scheuerell, Steve - OREGON STATE UNIVERSITY
item Mahaffee, Walter

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 12, 2005
Publication Date: August 15, 2006
Citation: Scheuerell, S., Mahaffee, W.F. 2006. Variability associated with suppression of gray mold (Botrytis cinerea) on geranium (Pelargonium x hortorum) by foliar applications of non-aerated and aerated compost teas. Plant Disease. 90:1201-1208.

Interpretive Summary: This research was conducted to examine the use of compost tea for control of leaf diseases using gray mold (Botrytis cinerea) of geranium as a model system. Numerous compost tea production parameters were manipulated to increase the consistency of disease suppression, including compost source, stirring, aeration, nutrient additives, production duration, and applying finished compost tea with spray adjuvants. For non-aerated compost tea (NCT), the most consistent disease suppression was associated with particular compost batches and increasing the production time to 14 days. Continuously aerating compost tea did not significantly (P < 0.05) increase disease suppression compared to non-aerated compost teas. As with non-aerated compost teas, preparing aerated compost tea (ACT) with nutrient additives did not increase disease suppression. However, the addition of spray adjuvants to aerated compost teas just prior to application significantly increased disease suppression. These data indicate that compost teas made from certain batches of compost can suppress gray mold of geranium; however, disease suppression across all sources and production methods is inconsistent.

Technical Abstract: Compost teas were shown to significantly reduce leaf infection severity on geranium caused by Botrytis cinerea under environmental conditions that are extremely favorable for disease development. However, the majority of compost teas did not significantly suppress B. cinerea infection of geranium. Numerous compost tea production parameters were manipulated to increase the consistency of disease suppression, including compost source, stirring, aeration, nutrient additives, production duration, and applying finished compost tea with spray adjuvants. For non-aerated compost tea (NCT), the most consistent, significant (P < 0.05) disease suppression was associated with particular compost batches and increasing the production time to 14 days. Applying compost tea removed from the surface of open production containers compared to deeper liquid had a consistent positive, but not significant (P < 0.1) effect. Periodic stirring or adding nutrients at the onset of production to increase microbial populations had little effect. Continuously aerating compost tea did not significantly (P > 0.05) increase disease suppression compared to non-aerated compost teas. Preparing aerated compost tea (ACT) with nutrient additives did not significantly (P > 0.05) increase disease suppression. Applying ACT with spray adjuvants significantly (P < 0.05) increased disease suppression. These data indicate that compost teas made from certain batches of compost can suppress gray mold of geranium, however, disease suppression across all sources and production methods is inconsistent.

Last Modified: 11/28/2014
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