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Title: Effectiveness of Soil Solarization on Management of Phytophthroa rubi and Pratylenchus penetrans in Northwestern Washington

item GIGOT, J - Washington State University
item Zasada, Inga
item WALTERS, T - Washington State University

Submitted to: Society of Nematologists
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2009
Publication Date: 12/1/2009
Citation: Gigot, J., Zasada, I.A., Walters, T. 2009. Effectiveness of soil solarization on management of Phytophthroa rubi and Pratylenchus penetrans in northwestern Washington. Society of Nematologists. 41(4):332.

Interpretive Summary:

Technical Abstract: Soil solarization is an important component of soil borne disease management systems in many regions. Over 90% of the nation’s processed raspberries are grown in Washington State. Currently, broadcast pre-plant fumigation is used to manage soil borne pathogens, a practice that is expensive and chemically intensive. Solarization (SOL) and a combination of SOL plus dripline fumigation (Inline™ Telone:chloropicrin 61:33, 400 L/HA) were investigated as alternatives for control of Phytophthora rubi (Pr) and Pratylenchus penetrans (Pp) in northwestern WA. Field plots were established at Washington State University-Northwestern Washington Research and Extension Center in Mount Vernon, WA in June 2007. Plots (3 x 30 m) were set-up as a randomized complete block with five replications. Nylon mesh bags of Pr inoculum were placed at 15, 30 and 45-cm depths and harvested in March 2008, and pathogen survival in these bags was assessed in a greenhouse bioassay with tissue culture-propagated raspberry plants. Soil samples for nematode population density assessment were collected after SOL and fumigation in Oct 2007. Raspberry roots samples were collected in November 2008 for Pp quantification. At 15, 30 and 45-cm, SOL plots accumulated 358, 38 and 0 hrs of heat units above 29 oC, respectively. There was no significant effect of SOL on the proportion of diseased roots as compared to the untreated control (UTC) or SOL-Inline treatments. The average root rot rating at all three depths for SOL (6.6) was significantly (P < 0.05) higher than the UTC (5.7) and similar to SOL-Inline (6.3). Root and shoot dry weights were not different between treatments. The Pp population density per g soil was significantly (P < 0.05) lower in SOL-Inline (8) compared to SOL (82.8) or the UTC (142.2). Pratylenchus penetrans per gram of fresh root was significantly lower in SOL (14.5) and SOL-Inline (1.7) compared to the UTC (62). Combining SOL with additional soil management techniques, such as dripline fumigation, may increase the effectiveness of this technology. Further work is underway to explore the use of organic amendments with SOL for increased control of Pr and Pp in raspberry systems.