Potential global distribution of blueberry twig blight (Phomopsis vaccinii) predicted by two species distribution modeling approaches

Blueberry twig blight, caused by Phomopsis vaccinii (teleomorph Diaporthe vaccinii) is a severe endemic disease in the Eastern and Northwestern USA. It has also been found at a few locations in Europe, Canada, and one location in Chile and China. In the latter two countries and most of Europe, the pathogen was eradicated after being found, except for Latvia. Publications on its occurrence in the USA and Canada would indicate that this is a cool-season pathogen. Models on the potential spread of P. vaccinii have not been published. The database of the National Plant Diagnostic Network (NPDN) could possibly be used to predict the potential spread of this pathogen. Published data on worldwide occurrence were inventoried and supplemented with NPDN data. GPS coordinates were estimated at the county level. Occurrence data and long-term climate data from the Worldclim website were entered in the species distribution models MaxEnt and Multi-Model Framework. The models predicted that the climate in central and eastern USA and the west coast of the USA and Canada would be conducive to blueberry twig blight. Large areas in Europe, Eastern Australia and New Zealand, and smaller areas in South America and East Asia would be conducive too. All locations where twig blight had been identified were correctly predicted to be conducive. Precipitation in the driest quarter of the year contributed most to the prediction, followed by mean annual temperature. The models indicated that P. vaccinii is not necessarily limited to cool climates, although the optimal annual average temperature is 10°C according to the MaxEnt model. Thus, the NPDN database can be an important source of information for the prediction of the potential global spread of a plant pathogen.