Optimizing Integrated Pest Management in Mesotunnels for Organic Acorn Squash in New York

Organic production of cucurbits in New York is challenged by a complex of biotic stresses, including insect pests, diseases, and weeds. The recent emergence of cucurbit yellow vine disease (CYVD), caused by the bacterium Serratia marcescens and spread by squash bugs (Anasa tristis), in New York is of urgent concern due to the lack of synthetic insecticide alternatives and effective complementary organic management practices. Cucurbit productivity is also related to effective weed management in the furrow (inter-row space between the raised beds) to prevent resource competition for plant growth and ease of harvesting. Field trials were conducted in organic acorn squash (cultivar Table Ace) during 2021 and 2022 to evaluate the effect of exclusion netting in a mesotunnel on pest populations, disease incidence, and weed management techniques in the furrow. Treatments were landscape fabric in the furrow with or without a mesotunnel and a mesotunnel with either a ryegrass/white clover or ryegrass cover crop in the furrow. Mesotunnels significantly reduced squash bug populations and CYVD but did not affect the incidence of the predominant foliar diseases, powdery mildew, downy mildew, or Alternaria leaf spot. The ryegrass/white clover and ryegrass cover crops produced equivalent biomass and weed suppression in the furrow. Treatments had no significant effect on fruit number or weight, or the number of marketable fruit, but mesotunnels reduced the incidence of soft and sunburned fruit. The tradeoffs and benefits of mesotunnels and furrow management for organic acorn squash production are discussed.