Infection develops at the base of an infected spur and spreads upward and to a lesser extent down and to the sides. Cortical tissues are brown to bright orange. First noticed in late winter or early spring. As the tree brads dormancy gum is produced by the tree and breaks through the bark. Bacteria move intercellularly and advance into the bark and into the medullar rays of the phloem and xylem.
Cankers develop in the fall after dormancy sets in.
At the end of cold weather the cankers develop quickly. The ability to wall infection seems to be correlated with varietal resistance but is also affected by the age and succulence of the plant, the temperature and rainfall during a season, and the type of root sock on which the tree is growing. It came to the U.S. from Japan. It hit Florida in 1910 and spread to the Gulf States and beyond. It was eradicated from Florida in 10 years.