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Our long-term goal is to provide the raspberry industries in the Western States with disease management information and solutions to manage soil borne diseases. <P>We have two specific objectives in this project, which will emphasize alternatives to broadcast fumigation. Our first objective is to develop better decision-making tools, including: better determination of Phytophthora spp. in Western States raspberry production, characterize differences in populations between strawberry and raspberry fields infected by P. rubi, P. fragariae and other Phytophthora spp. , and identify sources of Pratylenchus penetrans resistance in red raspberry and related Rubus spp.<P> Secondly, we will develop sustainable management systems, including long-term evaluations to determine whether bed fumigation and alleyway management methods sufficiently delay pathogen re-colonization into planting beds to permit successful plant establishment. Evaluate non-chemical pretreatment methods, including alley pretreatment combined with shifting rows, and Anaerobic Soil Disenfestation. Determine suitability of raspberry plug plants following bed fumigation. <P>Our expected Output Activities include : conduct of field, laboratory and greenhouse experiments, and mentoring of a Ph-D level graduate student and postdoc. We will also administer surveys to growers regarding their attitudes and understanding of fumigant usage, acceptance of alternatives, perceived risk of nematodes, reasons to fumigate and future concerns. The first survey will be the baseline against which to monitor progress of this project. <P>Events will include fumigation field days presented in September 2010 and 2012. Products will include a PhD level student graduated from Washington State University, and a Postdoctoral Research Associate completed at USDA-ARS Horticultural Crops Research Laboratory in Corvallis. <P>Published material will include updates on research progress distributed to berry growers via the Peerbolt Crop Management Newsletter and the Washington Red Raspberry Commission newsletter. <P>Updates and project results will also be available on the WSU Mt Vernon REC Small Fruit Horticulture website. <P>Results will also be presented at scientific meetings, including the annual meetings of the American Society for Horticultural Science, American Phytopathological Society, and the Society of Nematologists. We will also present information at the annual caneberry extension meeting in Watsonville, CA and on Mark Bolda's (UC Cooperative Extension-Santa Cruz County) blogs in English and in Spanish.
Non-Technical Summary: Raspberry production in the western U.S. is a $280 M industry covering 14,500 acres. Soil borne diseases, especially Phytophthora root rot and the plant-parasitic nematode Pratylenchus penetrans, threaten raspberry productivity in these States. Broadcast preplant soil fumigation is widely used to manage these diseases, but new regulations will soon make fumigation prohibitively difficult and expensive for many growers. Through a multi-disciplinary and -state effort, we will conduct research and disseminate information to help growers make the transition away from broadcast fumigation; we will achieve this goal in two ways. First, we will develop decision-making tools to help growers make more informed choices about the risk of soil borne diseases in their fields. We will develop tools for Phytophthra spp. (identification and characterization) and plant-parasitic nematodes (damage thresholds and identification of Rubus spp. resistance to Pratylenchus penetrans). Second, we will develop sustainable management systems to help growers manage soil borne diseases in compliance with the new regulations. We will evaluate bed fumigation, alleyway cover crops and anaerobic soil disinfestation as replacements for broadcast fumigation. We will also evaluate a novel plant plug system as a tool to take full advantage of the benefits of bed fumigation. We will test and promote these innovative IPM strategies in the major U.S. raspberry production regions. In addition, these strategies will readily apply to other crops such as blueberry, strawberry, and grape which are affected by similar diseases and fumigation restrictions. This project addresses the goal of the Risk Avoidance and Mitigation program to enhance the development and implementation of innovative, ecologically based sustainable IPM strategies and systems for an area-wide agroecosystem. <P> Approach: We will isolate Phytophthora from infected raspberry or strawberry roots from WA, OR and CA. Isolates will be identified using protocols based on sequencing of the ITS region and/or PCR-RFLP. A BLAST search will be performed to compare the consensus sequences with those deposited in Phytophthora-ID. For non-matching isolates, we will identify the species by sequencing additional DNA loci and by evaluation of morphological traits. Population structure will be determined using Amplified Fragment Length Polymorphisms. We will evaluate 10 Rubus interspecific hybrids and commercially-available cultivars for resistance and tolerance to P. penetrans in an infested field. Genotypes will be planted spring 2012 and cane number and length determined that fall. Root and soil P. penetrans population densities will be determined periodically. We will destructively sample one plant in each plot during the second year for biomass and nutrient analysis. We will identify two Washington and California raspberry fields with P. rubi or P. penetrans, and that are scheduled for fall fumigation and re-planting the following spring. Four treatments will be replicated: Conventional broadcast fumigation and alleyway management (mechanical and chemical weed management), bed fumigation (fumigant and tarp applied to planting bed only) with conventional alleyway management, bed fumigation with alleyways managed to suppress P. penetrans and P. rubi using soil amendments and cover crops, and nontreated control. Raspberry plants will be established the following spring. P. penetrans and Phytophthora will be evaluated in the spring and fall of each year. Fruit yields will be evaluated in years 2 and 3. Middle row management pretreatments will be evaluated in a third field. These include: amendment with Brassica seed meal, amendment with composted dairy solids, cover crop of Saia oats or Wheeler rye, nontreated check, and fumigated control. Phytophthora and P. penetrans will be evaluated in alleyways in spring and fall of each year. Raspberry plants will be removed after the 2011 harvest. Planting beds will be established in the former alleyways for planting spring 2012. P. penetrans and Phytophthora will be evaluated twice a year. Fruit will be harvested July 2013 and 2014. We will evaluate Anaerobic Soil Disinfestation in greenhouse experiments. P. rubi or P. penetrans will be incorporated into soi with wheat bran and other readily degradable carbon sources. Treated, inoculated soils will be placed in sealable containers, saturated, and sealed with VIF mulch film. Soil Redox potential will be monitored throughout the duration of the experiments. P. rubi will be evaluated by q-PCR and with our greenhouse bioassay and P. penetrans will be extracted by sieving/centrifugation and enumerated. To evaluate plug plants for bed fumigation, we will compare dormant canes planted in March , actively growing tissue culture-propagated plants in 72- cell trays planted after danger of frost is past, and dormant or actively growing plants in higher volume or deeper plugs. Percent viability, above-ground biomass, cane number and cane height, and yield will be evaluated.