Phytophthora rot of apple fruits has been reported from widely separated growing districts. The disease seldom causes serious damage and is rarely seen on the market.
Diseased apples are most likely to be found in low-grade fruit shipments.
In the early stages, the diseased tissues are as firm as adjacent healthy tissues. The vascular bundles and strands are usually a darker brown than the surrounding tissues. In advanced rots, the affected older or central portion may become somewhat spongy, more intensely discolored, and deeply water-soaked. However, the rot rarely becomes soft and mushy. The fruit rot is caused by a soil organism, Phytophthora cactorum , which is also responsible for collar rot, a destructive disease of fruit trees.