52 Nebraska Agricultural Exp. Station, Research Bui. 10 
Scott and Rorer further say, in effect: On the fruiting branches the 
cankers appear first as small purple or blackish blotches. As they 
increase in size they become brown in the center with a purple 
margin but finally become gray. The bark soon cracks around 
the cankers, especially along the lateral edges. On rapidly grow- 
ing shoots, particularly water sprouts, the cankers have the same 
general appearance as on fruiting branches, but are much larger, 
often measuring an inch or more in length and sometimes girdling 
the stem. The fungus lives over winter in the cankers, which be- 
come larger from year to year and may continue to grow for several 
seasons. Frequently, however, the cankers are cut off from the 
healthy tissue by cracks, dry up, and later the wound may heal 
over. 
The cankers themselves do not, as a rule, seriously injure the 
tree, but in some cases, on susceptible varieties, such as North- 
west Greening, Missouri, Limber Twig, and Red Astrachan, the 
trees may become so badly affected that much of the bearing 
wood will be killed and the trees materially weakened. The 
leaves also are attacked, the fungus causing irregular light brown, 
yellowish, or whitish spots, measuring \ k; inch or less in diameter. 
The spots often appear in great numbers scattered promiscuously 
over the surface of the leaf, on the veins, midrib, and petiole. The 
Fig. 9 — Blotch cankers on twigs 
