Evaluating the impact of Surround WP on blueberry aphid colonization, pollinator abundance, and photosynthesis in western Washington blueberries

Aphids in the genus Ericaphis are significant pests of blueberry in Western Washington because they are an efficient vector of blueberry scorch virus and blueberry shock virus. The aphid lifecycle is complex, with sexual and asexual reproduction resulting in various life stages throughout the year. In the fall, sexual aphids lay eggs that overwinter and hatch into parthenogenetic, wingless females, contributing to a population peak in the spring. Within commercial fields, aphids are typically treated with broad-spectrum insecticides in the spring, which can be harmful to pollinators, especially during blueberry bloom. Surround WP, a kaolin clay-based insecticide, is a repellent that can be utilized during bloom, due to its low-risk to pollinators. When kaolin is applied to plants, it forms a distinguishable white, dusty film, irritating insect exoskeletons and reflecting UV light. Kaolin also provides sunburn protection and heat stress mitigation for plants without affecting photosynthesis. Kaolin has been shown to successfully manage aphids and related hemipterans in other regions, and the product needs further testing in Washington. Our field trial aims to examine the impact of kaolin on blueberry aphid colonization in the fall and subsequent spring season (2024-2026), as well as the effects on pollinator abundance and plant photosynthesis. Our hypothesis is that fall and spring applications of kaolin could disrupt fall aphid colonization and therefore reduce the spring population peak. This presentation will cover background information on blueberry aphids, management strategies, experimental design, and preliminary research findings.