Objective As an important ecological and economic tree species, walnut tree belongs to Juglandaceae deciduous and has been widely cultivated in the world. Anthracnose caused by Colletotrichum species including C. gloeosporioides, C. siamense etc., is one of the main diseases of walnut. According to the known distribution of walnut anthracnose, the range of its suitable growing areas was predicted and analyzed in China and Yunnan province, and the potential distribution range of walnut anthracnose in China was identified, which would help to take scientific and efficient monitoring and prevention measures in production and reduce potential ecological and economic losses.

MethodsThe species distribution model MaxEnt was used to develop the model by selecting bioclimate variables and optimizing model parameters, and then applied the model to predict the suitable habitat of walnut anthracnose in China and Yunnan province. ArcGIS software was used to visualize the prediction results and deal with area statistics, and the results of the model were used to analyze the main environmental factors affecting walnut anthracnose.

ResultsThe results showed that the main environmental factors affecting the adaptability of walnut anthracnose were annual rainfall, rainfall in the driest month, temperature seasonality, average temperature in the coldest quarter, annual average temperature, isotherm, average daily range, and average rainfall in the warmest quarter. The total area of walnut anthracnose in China's ecological suitable areas was about 3.1712 million square kilometers, accounting for 33.03% of the total land area. It was mainly distributed in all areas of central, eastern and southern China, as well as most areas in the southwest and a few areas of the northwest, north and northeast in China. The suitable growth area of walnut anthracnose was mainly concentrated in western Yunnan, about 226400 square kilometers, accounting for 57.44% of the total area of the province.

Conclusion Walnut anthracnose has a relatively wide range of suitable growth areas in China, especially in Yunnan province, where anthracnose has the largest number of occurrence points and the widest distribution of highly suitable areas. The predicted suitable growth areas are consistent with the obtained distribution points of walnut anthracnose. In the future, the prediction and control of walnut anthracnose should be further strengthened in combination with the biological characteristics and field distribution of the local walnut anthracnose pathogen.