Soil treatments for the elimination of Phytophthora ramorum from nursery beds: current knowledge from the Laboratory and the field

Abstract

Over the past years, ramorum blight, caused by Phytophthora ramorum, has reoccurred at specific nurseries. In many cases, the re-emergence of the disease could not be traced to a second introduction. Since it is known that P. ramorum propagules can survive for over a year in soil, it is not unreasonable to hypothesize re-emergence of the disease may be attributed to inoculum surviving in soil beds. Although the United States Department of Agriculture- Animal and Plant Health Inspection Service (USDA-APHIS) Confirmed Nursery Protocol recommends soil beds be treated with heat, chloropicrin, dazomet, metam-sodium, or methyl bromide, the number of re-emergent nurseries suggests failures of these recommendations. Label recommendations may not provide complete eradication. For example, P. ramorum was still detectable after dazomet (Basamid®) (158.77 kg/0.40 ha = 350 lb/acre) was applied to an infested nursery site and sealed with a water cap as opposed to a polyethylene tarp. Additionally, some of the recommended methods are not feasible in many nursery settings due to lack of chemical availability, buffer zone requirements, or township caps. More needs to be known about treatment materials and methods to provide nurserymen with viable options to manage this disease.

Parent Publication

• Proceedings of the sudden oak death third science symposium

Citation

Yakabe, L.E.; MacDonald, J.D. 2008. Soil treatments for the elimination of Phytophthora ramorum from nursery beds: current knowledge from the Laboratory and the field. In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 113-114