P-095 - Fungicide Performance under Solid-set Overhead Sprinkler and Tractor Application Systems on Carrot Alternaria Leaf Blight

Florida's carrot industry has grown significantly in recent years. The value of Florida's carrot production in 2022 was estimated to be over $46.7 million. However, Alternaria leaf blight (ALB), caused by Alternaria spp., poses a major threat to Florida carrot production. Effective ALB management relies heavily on fungicides, but application methods can influence their efficacy. A 2023-2024 field trial in Live Oak, Florida, investigated the impact of application method on ALB control using six fungicides: three conventional (Merivon, Miravis Prime, Fontelis) and three Organic Materials Review Institute (OMRI)-listed (Stargus, Oso 5% SC, Nordox 75WG). The study compared solid-set overhead sprinkler irrigation and tractor application methods. Disease severity was assessed using the Horsfall-Barratt scale, and AUDPC was calculated to quantify disease pressure over time. The results indicated conventional fungicides provided significantly superior ALB control compared to the OMRI-listed options, regardless of whether they were applied via sprinkler or tractor. While Merivon and Miravis Prime provided effective control with both sprinkler and tractor applications, Fontelis exhibited significantly better performance when applied via tractor. This research highlights the importance of fungicide selection and application method for ALB management in Florida carrots. Fontelis may be best utilized with tractor application for optimal disease control. Further research is needed to understand factors influencing fungicide performance differences across application methods.