Weather Conditions and the Risk of Tomato Spotted Wilt Virus (TSWV) in Tomato Producing Areas in Southern Ghana

Tomato farmers in southern Ghana incur losses due to the infection of crops by the tomato spotted wilt virus (Orthotospovirus tomatomaculae). The occurrence of the virus varies among individual tomato crops, influenced by the vector population and changing weather patterns. This study investigates the effect of early spring weather conditions (February–March) on the risk of occurrence of tomato spotted wilt virus in tomato-producing regions in southern Ghana. Interviews and focus group discussions were conducted with farmers in the Ada East and West Districts to generate information on the period, frequency and the severity of tomato spotted wilt virus occurrences for the period 2020–2023. Meteorological data for the focal years were analyzed to identify the weather variables that influenced the occurrence of the virus, including the specific months of occurrence. Logistic regression analysis shows a high correlation between temperature and the occurrence of TSWV. Findings indicate that high temperature (29°C–32°C) recorded between January and March in the area correlate with farmers' observations of the virus. Observation by farmers that the viral infection started from March imply that it could have originated in the nursery and transported to the farm. The practical implication of the findings for management requires that farmers plant resistant varieties, frequent scouting for thrips, adoption of hygienic cultural practices, while agricultural extension agents and meteorological stakeholders provide farmers with timely agronomic information and accurate weather forecasts to enable early detection and response.