Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-046-040-G
Project Type: Grant
Start Date: May 1, 2023
End Date: Oct 31, 2026
Objective:
1. Quantify Blueberry Scorch Virus (BlScV) incidence in WA and OR production regions.
2. Develop improved sampling procedures for BlScV testing (ELISA and PCR).
3. Provide growers (within our sampling program, and industry wide) with a comprehensive management strategy, including reliable sampling procedures and vector management procedures based on current research.
Approach:
Our goal is to test 100 fields in WA and OR for BlScV and for Blueberry Shock Virus (BlShV), a virus with similar symptoms that may mask BlScV symptoms. Fields sampled will be geographically diverse and include all major production
areas in Washington (Northwestern Washington, Central Washington (The Columbia Basin), Southwest Washington and Lewis County) and Oregon’s Willamette Valley, Hood River valley, Eastern, and Southern production regions).
At each field to be sampled, we will record grower contact information, cultivar, region, and planting age. Grower identity and contact information will remain confidential. We will collect five samples from each field: Four of these will be from symptomatic plants (if present), the fifth sample will be from asymptomatic plants. Each sample will contain 25 leaves, leaf bud clusters or flower bud clusters: five from each of five plants. Each plant sampled will be labeled and its location as well as presence of absence of symptoms recorded. Sample bags will be labeled and stored in a cooler or refrigerator until they are transferred to Phyto Diagnostics (Abbotsford, BC; the same lab used by BC growers) to be tested for BlScV and BlShV by ELISA. Results will be tabulated to record incidence of each virus within each blueberry production region, as well number of positive tests from each. Lastly, each field sampled will have a random 100-plant transect performed where the number of plants exhibiting viral collapse symptoms will be counted.
We will select two BlScV-positive plants each of three cultivars or extensive sampling at bloom, the time at which many growers would note symptoms and sample. We have field plants identified and labeled for this purpose. However, if growers remove plants prior to our sampling, we may not have all 3 cultivars to sample. If necessary, we will fall back on plants testing positive in the first round of sampling. From each plant, we will collect 5 flower shoots and 5 leaf shoots each from diseased tissue (when present), from healthy tissue sharing a branch with diseased tissue (when present), and from healthy tissue not near diseased tissue. Thus, there will be 2-6 samples per plant. These will be sent to the USDA for ELISA and PCR analysis for BlShV and BlScV. Some duplicate samples may be sent to Phyto Diagnostics for comparison. For each cultivar, we will compare the percentage of positive tests for leaf vs flower shoots, and for diseased, neighboring diseased, and not neighboring diseased tissue.
Production of online resources which include an aggregate of best procedural findings from this project and other practical management considerations will be created. Distribution will be direct to growers, through commission communication channels, through the Small Fruit Update, and a webpage on the Northwest Berry Foundation site. Commercial growers will have confident steps to identify, sample, and manage BlScV with this material.
