Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2023
Publication Date: N/A
Technical Abstract: Boxwood blight is primarily a foliar disease that causes substantial losses in boxwood, the top-selling broadleaf evergreen nursery plant produced in the USA. The fungal pathogen, Calonectria pseudonaviculata, produces conidia that are splash dispersed and which germinate and infect through stomata on the leaves or stems. Spore germination is a key process for infection to occur; however, under lab conditions, spore germination rates of C. pseudonaviculata are low on nutrient rich media in comparison to germination on leaves. This suggests the spores may require specific host cues for germination. We conducted two experiments to identify factors that affect C. pseudonaviculata spore germination. First, we compared germination rates of C. pseudonaviculata spores on detached boxwood leaves, potato dextrose agar, and microscope cover slips. Second, we tested whether the presence or absence of detached boxwood leaves affects spore germination on coverslips. We found that C. pseudonaviculata spores will germinate on host leaves as well as on coverslips placed in close proximity to host leaves. Spores exhibit poor germination in the absence of the host. These findings suggest that host volatiles may play an important role in C. pseudonaviculata spore germination.