Invasive root pathogens are a major threat to forest health worldwide, and the fungal pathogens that cause Armillaria root disease (Armillaria species) impact diverse tree species and are distributed globally. Studies to document the distribution of Armillaria species are essential for assessing potential invasive threats and potential impacts of climate change. Collaborative studies have begun to document the distribution of Armillaria pathogens in Mexico, and a previously unknown Armillaria species was found that represents an invasive threat to other areas.
The fungal pathogens that cause Armillaria root disease (Armillaria species) on diverse tree hosts around the world can act as invasive pathogens when they are introduced to new areas. In many areas, surveys of the native Armillaria species are lacking, so it is difficult to recognize when an Armillaria species is invasive. In recent years, DNA-based diagnostics have allowed for the precise identification of Armillaria species present on a site. DNA-based diagnostics were also used in an ongoing collaborative study with multiple institutions in Mexico to identify Armillaria species associated with root disease in peach (Prunus persica) and other trees Mexico. Most notably, this study showed that a previously undescribed species of Armillaria was causing most of the root disease on peach trees. This previously unknown species was characterized as a newly described species, Armillaria mexicana. This Armillaria species is of great interest because it represents an invasive species threat for many global areas where it is not known to occur.
Continued studies are needed further document its distribution and geographic areas where it represents a potential invasive species threat. A recent study identified a rootstock for peach that is resistant/tolerant to Armillaria root disease caused by A. mexicana.