The gynoecial infection pathway of Monilinia vaccinii-corymbosi in lowbush blueberry (Vaccinium angustifolium)

Monilinia vaccinii-corymbosi (Reade) Honey is an economically important pathogen of lowbush blueberry (Vaccinium angustifolium Aiton) which causes blighting of leaves and flowers and mummification of fruits. This study was conducted to determine if infection of lowbush blueberry gynoecia occurs through colonization of the stigma. Sections of gynoecia inoculated with conidia were examined by brightfield microscopy. Conidia germinated on the stigmatic surface 1–3 d following inoculation to form hyphae winch invaded the stylar canal and other tissue down to the ovules. The infection pathway observed was identical to that of pollen tubes following pollination. After invasion of the ovary fungal colonization continued until the entire fruit wall was colonized with mycelium.