New publication on steam treatment for Phytophthora eradication

Schweigkofler, W.; Kosta, K.; Huffman, V.; Sharma, S.; Suslow, K.; and Ghosh, S. 2014. Steaming Inactivates Phytophthora ramorum, Causal Agent of Sudden Oak Death and ramorum Blight, from Infested Nursery Soils in California. Plant Health Progress. 15(1): 43 – 47.

Abstract: Nursery trade plays a major role in the long-distance spread of Phytophthora ramorum, the causal agent of Sudden Oak Death (SOD) and ramorum blight of ornamental plants. Under federal regulations, nurseries found positive for P. ramorum must destroy infected plants and treat infested soils. The use of steam is an effective method to thermally inactivate P. ramorum from nursery soils as demonstrated at the National Ornamental Research Site at Dominican University (NORS-DUC) and one commercial nursery in the Central Valley of California. Heating up the top soil layer (0-30 cm) to 50°C for 120 minutes resulted in complete thermal inactivation of P. ramorum. Consequently, the commercial nursery was released from federal quarantine. Steaming can be a fast, reliable, and sustainable option for treating nursery soils.

Soil solarization - a method for removing P. ramorum from infested soil

Soil solarization under the test conditions in CA appears to offer an effective means of eliminating P. ramorum from at least the upper layers (top 15 cm) of the soil profile, where most of the naturally occurring inoculum is located.  Efforts are underway to model the survival of P. ramorum in relation to soil temperature and moisture.  Additional research in 2013 is aimed at understanding how to maximize the effectiveness of solarization in killing soilborne Phytophthora species in CA, OR, and WA, and to determine how the presence of crushed rock on the soil surface affects soil heating. Commercial nurseries in CA, OR, and WA interested in participating in 2013 solarization trials are encouraged to contact Jennifer.Parke@oregonstate.edu for further information.

Read more here - COMTF June 2013 newsletter.