Biological control of tanoak and bay laurel resprouts using the fungus, Chondrostereum purpureum
| Authors: | Marianne Elliott, Gary Chastagner, Simon Shamoun, Grace Sumampong, Ellen Goheen, Alan Kanaskie |
| Year: | 2013 |
| Type: | General Technical Report |
| Station: | Pacific Southwest Research Station |
| Source: | In: Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 134-136 |
Abstract
In southwest Oregon, an aggressive program of cutting and burning host plants in an effort toeradicate Phytophthora ramorum was initiated. It was soon apparent that tanoak (Notholithocarpus densiflorus (Hook.& Arn.) Manos, Cannon& S.H. Oh) resprouts were highly susceptible to P. ramorum and that infected sprouts hamper eradication efforts by maintaining inoculum on site (Hansen and Sutton 2006). The basidiomycete fungus, Chondrostereum purpureum causes a white rot of mostly broadleaf trees and has a wide host range. It invades through fresh wounds in the xylem or cut stumps and is a weak pathogen that can survive as a saprophyte. After the host tree is weakened or killed, C. purpureum is quickly replaced by other, more competitive decay fungi that are naturally occurring in the environment. This fungus is used as a biological control agent for woody vegetation all over the world (Becker et al. 2005, Bourdot et al. 2006). A preparation of mycelium of the fungus C. purpureum is registered under the trade name "Chontrol= Paste" in the United States and Canada for use as a biological control agent and has been tested as a stump treatment on many hardwood species (EPA Registration No. 74200-1, 2004; and PMRA Registration No. REG. 2004-09, 2004). Chontrol= is not registered for use in California, so indigenous isolates of C. purpureum are being obtained and formulated for use on California bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.), the host responsible for P. ramorum inoculum buildup in California.
In fall 2009, our research team established field trials near Brookings, Oregon to assess the bioherbicidal efficacy of the fungus C. purpureum on tanoak to inhibit resprouts. Chondrostereum purpureum was found occurring naturally on tanoak logs and stumps at other sites in the Brookings area. Laboratory testing of three California isolates of C. purpureum indicate that the fungus can colonize bay laurel stems, and further testing under natural conditions is planned in California. If a formulated product of C. purpureum and/or its mixture with other stem and wood decay fungi applied to tanoak and bay laurel does inhibit the trees from growing new sprouts, this P. ramorum inoculum reservoir would be reduced or eliminated in the ecosystem. In areas where the application of herbicides is not prudent or permitted, this biocontrol treatment would be an indispensable alternative to chemical herbicides.