Morphological and Phylogenetic Resolution of <i>Diplodia corticola</i> and <i>D. quercivora</i>, Emerging Canker Pathogens of Oak (<i>Quercus</i> spp.), in the United States

In Mediterranean Europe and the United States, oak species (Quercus spp.) have been in various states of decline for past several decades. Several insect pests pathogens contribute to this varying degrees, including Phytophthora cinnamomi, Armillaria spp., defoliators, and, wilt pathogen Bretziella fagacearum. More recently, two emerging canker pathogens, Diplodia corticola D. quercivora, implicated causing dieback mortality regions States. 2019, a fungal survey was conducted Mid-Atlantic region eastern Maryland, Pennsylvania, Virginia, West determine range impact quercivora on forest health A total 563 trees between red white family members were evaluated across 33 forests spanning 18 counties. 32 isolates encompassing three spp. recovered from 5,335 plugs collected 13 sampled Recovered included corticola, sapinea, as well Botryosphaeria dothidea, closely related Botryosphaeriaceae. Both sapinea members, whereas exclusive B. dothidea members. Of these species, most frequently isolated, followed by dothidea. Overall, low all counties, indicating that fungi, at levels detected, are not widely inciting region, but probably acting opportunistically when environment is conducive disease. To better understand relationships potentially their geographic origins, multigene phylogenetic study corresponding morphological conducted. 49 Spain, France, Italy, States assessed. Across regions, formed strongly supported monophyletic clade sister subclades, one Spain California second Virginia. subclades also exhibited overlapping spore measurements. These results support cosmopolitan pathogen, native both with possibility secondary introductions.