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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Research Project #442770

Research Project: Understanding the Extent of Symphylan Damage in Strawberry Production

Location: Horticultural Crops Disease and Pest Management Research Unit

Project Number: 2072-22000-044-030-G
Project Type: Grant

Start Date: May 1, 2022
End Date: Oct 31, 2024

1. Survey Willamette Valley strawberry production fields for presence of symphylans. 2. In three fields where symphylans are detected, compare yield, fruit quality and plant vigor between areas where symphylans are present and absent.

1. Survey. Fields to be surveyed will be identified by either a known site history of symphylans, site history of patchy weak areas, or sites that have the appropriate soil type. Within a field, symphylans will be surveyed in a gridded pattern using either shovel soil samples and timed counts, or potato baits, as recommended per Umble and Fisher. Selected fields will be surveyed weekly from May through June, when symphylans are most active near the soil surface. From July through September, symphylans tend to migrate more deeply into the soil so fields will be surveyed once per month. Data collected will be observational in nature (presence/absence of symphylans) and not statistically analyzed. 2. Assessing damage. Symphylans are root feeders, so the types of damage that may be observed include reduced plant vigor, root mass, problems with nutrient uptake, or differences in fruit size or yield. Symphylan populations are patchy in distribution, so within a field, the symphylans will likely only infest a subsection. Consequently, all comparisons of plant vigor and yield can be compared within the same field, in areas with and without symphylans present. A within field comparison eliminates differences in age, variety, soil type and cultural practices that would exist by comparing strawberries across sites. Three fields with symphylan populations (identified in Obj. 1) will be assessed in affected and unaffected areas of the field for the following potential damages resulting from symphylan feeding: Plant vigor – assessed with visual vigor ratings, leaf area measurements, and root weight. Nutrition – assessed with leaf tissue analysis. Fruit quality – assessed for fruit weight and fruit size. All data comparisons will be conducted via ANOVA, with the presence or absence of symphylans as the dependent factor.