It’s a fungal disease favored by low temperatures and high humidity. These conditions can be also reached in cases of frequent rains, irrigations and fog.
Preventive Actions: remove crop residues and leaves fallen the previous season. Perform a couple of treatments with cupric products (copper oxychloride) since pruning to buds and repeating the treatment after 10 days with temperatures above 20° C. Preventive products do not penetrate into plants and can be washed away, so after a rain the treatment should be redone.
Curative Actions: triazoles, also useful for combating powdery mildew and other pathologies such as rust and downy mildew, are still the most useful synthesis active ingredients to stop the Blackspot. These products penetrates into plants and starts working in the next few hours, therefore it is not washable in case of rains. The use of synthetic products is useful in particularly rainy years or periods: with few targeted measures, the plants are protected by the pathogen’s attack. Start using these products with the emergence of the first symptoms (small and sparse dots).