Improving Cucurbit Downy Mildew (CDM) Management Through Early Detection Using Affordable Airborne Spore Traps and Optimized Fungicide Timing in Ohio.

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Improving Cucurbit Downy Mildew Management through Early Detection Using Affordable Airborne Spore Traps and Optimized Fungicide Timing in Ohio.

Cucurbit downy mildew (CDM) is a highly destructive disease of cucumber production in Ohio, capable of causing rapid defoliation and severe yield losses within days of symptom appearance. Because visible symptoms occur only after infection has already been established, growers often rely on calendar‑based spray programs or symptom‑triggered fungicide applications that are poorly aligned with actual pathogen presence. This approach frequently results in unnecessary pesticide use, increased production costs, heightened fungicide resistance risk, and reduced ecological sustainability. There is a critical need for decision tools that allow growers to detect disease risk earlier and respond more precisely. This project will develop and validate a low‑cost, detection‑driven disease management system that shifts cucurbit downy mildew control from reactive to proactive. The project centers on the use of an affordable Rotorod airborne spore trap to detect Pseudoperonospora cubensis inoculum in real time and trigger fungicide or biological applications when pathogen presence is confirmed. By replacing calendar‑based spray programs with airborne pathogen detection as the decision trigger, this system enables growers to respond earlier and more efficiently to disease risk. Field trials will be conducted in Fremont, Ohio, a region with consistently high cucurbit downy mildew pressure. Two commercial cucumber fields one managed conventionally and one organically, will be equipped with two Rotorod spore traps and two Burkard volumetric spore traps to allow direct comparison of detection performance. Air samples will be collected every 7 days throughout the growing season and analyzed for pathogen presence. Fungicide or biological applications will be initiated based on spore detection rather than calendar timing. Project evaluation will measure time from pathogen detection to management action, number of disease control applications, disease severity over time, yield, and harvest duration. Outcomes from detection‑guided management will be compared with standard calendar‑based practices to quantify agronomic, economic, and ecological benefits. Expected outcomes include earlier disease detection, improved timing and reduced frequency of fungicide or biological applications, lower input costs, more stable yields, and extended harvest periods. Results will be disseminated through Ohio State University Extension programs such as extension crop walks, updates in the fruit and vegetable news website, and direct grower outreach. This project will provide Ohio cucumber farmers with a practical, affordable early‑warning system that improves profitability while strengthening the long‑term sustainability of cucurbit production systems.

Cucumber growers in Ohio and the North Central region, including conventional, organic, and Amish vegetable producers, are the primary audience for this project. This project will impact growers by improving how they interpret and respond to cucurbit downy mildew risk using airborne spore detection information delivered through Ohio State University Extension platforms and the Fruit, Vegetable, & Specialty Crop News website. Learning outcomes include increased awareness that cucurbit downy mildew can be detected in the air before visible symptoms appear, improved understanding of how airborne inoculum trends relate to disease risk, and improved ability to interpret weekly spore detection updates to inform fungicide and biological application timing. Growers will learn how to use posted spore detection reports to distinguish low-risk periods from high-risk infection windows. These learning outcomes will be reflected in website engagement metrics, grower feedback through Extension communication channels, and follow-up inquiries regarding interpretation of detection reports. Action outcomes include growers adjusting fungicide or biological application timing based on first reported airborne spore detection, delaying unnecessary sprays when inoculum is absent, and incorporating Extension-based spore monitoring updates into routine disease management decisions. Changes in action will be measured through documented shifts in recommended spray timing guidance, website usage analytics, and reported changes in decision-making behavior communicated through Extension and grower networks.