Phytophthora syringae is an oomycete plant pathogen known to infect nursery plants, particularly apple and pear trees.Laywisadkul, S., Fuchigami, L.H., Scagel, C.F., Linderman, R.G. Tree Growth Stage and Environment After Pathogen Inoculation Alters Susceptibility of Pear Trees to Phytophthora Canker. Open Horticulture Journal v3 (2010). It infects plants through wounded areas and is most pathogenic during cold, wet weather.
References
External links Index Fungorum USDA ARS Fungal Database