Survivability of Phytophthora ramorum in the Composting Process
S. Swain1, T. Harnik1, M. Mejia-Chang1, J. Creque2, M. Garbelotto1
It is estimated that millions of cubic tons of green-waste may be infected by Phytophthora ramorum in California. Disposal of this material is a major regulatory and management issue within the state. Here we show that composting effectively eliminates P. ramorum from green-waste. In laboratory heat treatment tests, wood chips and cankered stems from coast live oak, and infected bay leaves were all non-infectious after a two week exposure at 55 degrees centigrade. These same types of infectious plant materials were also used in field composting trials, utilizing both window and forced-air methods. All plant material extracted from compost piles was free from P. ramorum after two weeks. Pathogen viability of was tested both with direct plating on PARP selective medium and with pear-baiting, both before and after treatment. We will also show whether compost can be re-infected after treatment, and draw conclusions on the overall potential of composting as a viable method of eliminating P. ramorum from green-waste.
1Dept. of ESPM-ES, UCBerkeley, Berkeley, CA
2MacEvoy Ranch, Bolinas, CA
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