Development and deployment of a risk assessment index as a decision‐support tool for managing whitefly‐transmitted viruses affecting squash

BACKGROUND: Managing viruses transmitted by the sweet-potato whitefly (Bemisia tabaci Gennadius) is challenging as no single tactic provides adequate and consistent efficacy. These viruses are commonly found as a mixed infection in squash (Cucurbita pepo) plants; hence, they are collectively termed as the 'whitefly-transmitted virus complex' (WTVC) in this manuscript. While some tactics for managing WTVC are available, the relative impact of each management tactic in reducing disease severity is not known. This study aimed to quantify the relative importance of key management practices and develop a data-driven risk assessment framework to support integrated pest management (IPM) decisions. RESULTS: Utilizing data from 14 field trials (n = 14) conducted over 3 years (2020-2022) in southern Georgia, United States, a random forest model was applied to evaluate the influence of five management variables on WTVC severity. Planting date and use of row cover were identified as the most influential factors, followed by squash type, planting material, and mulch type. A risk assessment index was developed based on variable importance scores. The cumulative risk-point values showed significant positive correlations with standardized area under the disease progress curve (sAUDPC) in both training (r = 0.58, P < 0.001) and testing (r = 0.50, P < 0.001) datasets. Early planting, particularly yellow squash, the use of seedlings and the row covers were associated with reduced WTVC severity. CONCLUSIONS: Planting squash before the seasonal peak in whitefly populations, using row covers, and seedlings were associated with the lower WTVC risk. In our study, the resulting risk index and SquashRx application provided pre-season decision support for fall squash production in southern Georgia. As the index was developed and validated using data from this region, it should be validated before use elsewhere. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.