Predicted potential distribution of Sydowia japonica in Japan

Sydowia japonica, a dothidealean fungus, is a parasite that is specific to the male strobili of Japanese cedar. The fungus is a candidate for the control of Japanese cedar pollen dispersal, which is a cause of pollinosis. To evaluate S. japonica for bioherbicidal applications, it is necessary to characterise its potential distribution and environmental niche. Here, we predicted the distribution of S. japonica in Japan using field surveys and a maximum entropy model, and identified the environmental variables that influence its distribution. We identified S. japonica from a total of 87 localities in Japan through field surveys. Based on presence data and associated environmental variables, our model predicted that S. japonica is widely distributed in Japan, but concentrated in the Hokuriku and Kinki areas along the Sea of Japan. The model also predicted that the most important environmental variables influencing fungal distribution were sunshine duration in the winter and precipitation in the summer. This new information will contribute to the development of bioherbicidal applications for S. japonica.