Emerging Threats

Paradox Canker Disease

Symptoms of Paradox canker disease (PCD), including crown and root rot and ultimate tree death, appear similar to those caused by Phytophthora.  However, unlike cankers caused by Phytophthora, PCD  cankers tend to have rounded light-brown-colored lobes emanating from dark lobes, and Phytophthora has not been detected from PCD cankers.  The cause of PCD is unknown, and it has been found in all walnut producing counties that we have surveyed to date.



PCD map.jpg