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United States Department of Agriculture

Agricultural Research Service

Title: Microbial Recolonization of Compost after Peak Heating Needed for the Rapid Development of Damping-off Suppression Caused by Pythium Ultimum

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

Submitted to: Compost Science and Utilization
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 20, 2004
Publication Date: November 1, 2005
Citation: Scheuerell, S., Mahaffee, W.F. 2005. Microbial recolonization of compost after peak heating needed for the rapid development of damping-off suppression caused by pythium ultimum. Compost Science and Utilization. 13:65-71.

Interpretive Summary: This research was conducted to determine whether the formation of disease suppressive compost required inoculation with microbes after the heating phase of composting. Results indicate that the microflora surviving the heating phase of composting were not sufficient for the rapid development of disease suppression. Either the addition of microbes via inoculum or exposure to airborne microbes will be required in order to obtain disease suppressive compost. This information will help the compost industry provide a more consistent product for use in nursery potting media and reduce reliance on pesticide applications.

Technical Abstract: Compost removed from the hot (>55 C) core of yard trimmings compost piles was incubated under sterile conditions to observe whether suppression could develop due to cooling or if inoculation with an exogenous source of microbes is a critical factor. Suppression of damping-off caused by P. ultimum did not develop in the cooled compost over seven days of incubation, but compost inoculated 10% v/v with cured yard trimmings compost became suppressive after incubating for three to five days. The results indicate that the microbial community surviving thermophilic composting is not sufficient to support damping-off suppression and that recolonization of this material is needed to rapidly and consistently produce Pythium suppressive compost for use in greenhouse propagation of seedlings.

Last Modified: 12/18/2014
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