Nutrient source, temperature, and wetness duration influence fungal growth and conidial germination of Coniella vitis , the main causal agent of grape white rot in China

Grape white rot is an important fungal disease that affects grapes worldwide. Recently, Coniella vitis has replaced Coniella diplodiella as the dominant pathogen causing grape white rot in China. However, its key epidemiological parameters remain undefined, hindering the development of specific disease management strategies. Thus, the effects of temperature and nutrient conditions (culture media) on the mycelial growth of C. vitis, and the combined effects of temperature and wetness duration on conidial germination were examined in this study. The results showed that the mycelial growth of C. vitis was optimal at 20°C–30°C under organic-rich nutrient conditions. On water agar, conidia germinated across a temperature range of 10°C–35°C (optimum 20°C–30°C) and required wet periods longer than 2 h. Nonlinear models described these processes with estimated optimal temperatures of 27.3°C for mycelial growth and 23.9°C for conidial germination (R² > 0.89). This study revealed fundamental differences in the responses of C. vitis to temperature and wetness duration compared with C. diplodiella, providing key information for refining existing white rot prediction models and supporting the transition from calendar-based to risk-based precision fungicide applications.