Spraying fungicides is the most effective way to prevent late blight. For conventional gardeners and commercial producers, protectant fungicides such as chlorothalonil (e.g., Bravo, Echo, Equus, or Daconil) and Mancozeb (Manzate) can be used.
Phillimon Phillimon 7-8 chemical sprays are applied per season to control Phytophthora infestans. An integrated service for the prediction of tomato late blight is essential to define a more rational disease control scheme.
A forecasting model based on climatic data (IPI Model; Infection Potential Index) is used together with aerobiological monitoring of P. infestans sporangia. The IPI Model uses temperature, RH and precipitation to give ‘negative prognosis’ of the disease
(see Bugiani, R., P. Cavanni, and I. Ponti. "An advisory service for the occurrence of Phytophthora infestans on tomato in Emilia‐Romagna region 1." EPPO Bulletin 23.4 (1993): 607-613.)
Different pesticides and mix with plant immunity activators (like BABA (DL-3-aminobutyric acid + fungicide mancozeb) are significantly more effective comparing to a single pesticide and can reduce the risk of fungicide-resistant population development.