Gray mold of raspberry and blackberry

The causal agent of the disease is the necrotrophic fungus Botrytis cinerea, the sexual stage of which is known as Botryotinia fuckeliana. The pathogen overwinters in the soil and on plant debris, primarily infecting flowers and buds. Infection often occurs through the stigma, after which the fungus enters a latent state until the fruit begins to ripen.

Symptoms of infection on berries appear as brown spots that soften and become covered with an ash-gray layer of sporulation, leading to rotting in wet weather and mummification in dry weather. Large, diffuse spots form on the leaves. In cases of severe infection, the fungus penetrates the stems, which can lead to the dieback of shoots during the winter period.

Specific resistance genes or pathogen pathotypes associated with the genus Rubus have not been identified. Breeding of cultivars is conducted by selecting plants with morphological characteristics such as firm berry structure, less compact inflorescence structure to improve aeration, and specific biochemical defense properties.