Also known as Black Spot , it is a fungal disease that is favored by low temperatures and high humidity . These conditions can also be reached in case of overhead irrigation , frequent rains, fog .
Preventive actions : remove crop residues and leaves fallen the previous season. Perform a couple of treatments with cupric products (copper oxychloride) from pruning to hatching of the buds (brown treatments) and then after about 10 days with temperatures above 20 ° C. The preventive products do not penetrate the plant and are washable, so after a rain the treatment should be done again.
Curative actions : triazoles, also useful for fighting powdery mildew and other pathologies such as rusts and downy mildew, are still among the most useful synthetic active ingredients in stopping the black spot. The curative product penetrates the plant and enters the circulation within a few hours from the treatment so it is not subject to washout in case of subsequent rains. The use of synthetic products is sometimes useful in particularly rainy years or periods as with a few targeted interventions the plant is kept protected from attack by the pathogen. However, the advice is to start using these products at the onset of the first symptoms (small and sparse dots).