X-Force: Developing an integrated pest management program for the leafhopper vectors of X-disease

X-disease, a re-emerged leafhopper-vectored disease caused by Candidatus Phytoplasma pruni, is devastating commercial stone fruit (cherry, peach, nectarine) production in the Pacific Northwest region of the United States. At least six leafhopper species transmit X-disease phytoplasma, but recent surveys found the most abundant vectors in Washington orchards are in the genus Colladonus. Common groundcover weeds such as clover and dandelion are hosts for the pathogen and Colladonus, suggesting that groundcover weeds can promote disease prevalence in orchards. From 2020-2024 we evaluated control methods to reduce vector abundance and dispersal. Controls included grass planting, sucker removal, Extenday, or kaolin clay treatments. Colladonus populations were monitored using yellow sticky cards placed near the ground cover or in the canopy throughout the growing season. Most the cultural management tactics reduced Colladonus abundance within the block (Extenday and grass planting) or at the canopy level (kaolin clay and sucker removal). These results provide season-long cultural controls that can be used in integrated pest management programs for leafhopper vectors of X-disease to reduce insecticide input, and disrupt the source-sink dynamics of X-disease phytoplasma.