Collar Rot on Italian Alder Trees in California Caused by <i>Phytophthora siskiyouensis</i>

Fig. 1. Phytophthora collar rot on Italian alder trees: (A) grove of dying trees in a commercial landscape in Foster City, CA.



Image from Plant Health Progress article:
Collar Rot on Italian Alder Trees in California Caused by Phytophthora siskiyouensis