In severe cases, the entire tree can die if the cladosporium carpophilum fungal scab is not treated. Fungal spores which have over wintered on peach and nectarine plant debris such as fallen leaves and twigs, emerge. Fungal spores often over winter on fallen fruit which is known as a mummy, or mummies if there are more than one stone fruit. Fungal spores are also splashed from the lesions on the peach and nectarine tree bark. Water splashes fungal spores from these over wintered portions of infected peach and nectarine trees.
Wind can also spread fungal spores.
Those fungal spores which land on uninfected portions of health stone fruit trees, then begin to infect them rapidly. As cladosporium carpophilum scab infection continues on previouslu uninfected leaves, twigs and stone fruits the entire tree may quickly become reinfected and show signs of damage due to the spread of fungal spores which over wintered and spread each spring. This is why it is especially important to treat signs of cladosporium carpophilum scab as soon as they are evident as peach or nectarine tree damage and not let the damage continue the following year s growing season. Once spots appear, you have no choice but to ride out the rest of the season. Stone fruits which have spots but have not cracked can be eaten if peeled.