The effectiveness of ecologically acceptable ways of protection of field-grown tomato (Lycopersicon lycopersicum (L.) Karsten) from tomato late blight (Phytophthora infestans (Mont.) de Bary) in extreme weather conditions.

During the extremely wet vegetation season in 1999 the efficiency of protection of two cultivars of field grown tomato (Lycopersicon lycopersicum (L.) Karsten), 'Pick Rite' and 'GO 101', against tomato late blight (Phytophthora infestans (Mont.) de Bary) using three ecologically acceptable growing techniques and agrochemical measures (growing on black plastic mulch with no fungicides used, spraying with Dithane M-45 (mancozeb), spraying with Cuprablau-Z (Cu-hydroxide) and control) have been studied. It was found out that under such extreme weather conditions none of these measures can ensure an adequate protection of tomato. The highest yield of healthy fruits (0.30 kg per plant) was obtained after a threefold spraying with Dithane M-45 (mancozeb), the highest percentage of non infected fruits (38.1%) after a twofold spraying with Cuprablau-Z (Cu-hydroxide). The black plastic mulch, used with the intention to reduce the plant contact with the potential inoculum in the soil proved to be ineffective.