AN APPLE ORCHARD SURVEY OF WAYNE COUNTY, NEW YORK. 341 



in Orleans county in 1904. They were not very bad in more than a half 

 dozen orchards in each county, hut in a few orchards some trees had prac- 

 tically every leaf affected. Their local distribution even in the severe 

 cases seems to indicate that they do not spread rapidly. The ordinary 

 spraying has no effect on them, because they live within the leaf where 

 poison can not reach them. It is probable that kerosene emulsion applied 

 before the buds open would kill them. 



Injuries due to these three causes and to many other enemies that 

 attack the leaves are quite commonly confused with each other and with 

 spots that are sometimes caused by spraying". 



THE APPLE-TREE CANKER (Sphacropsis malornm Pk.). 



Description. The black, rough bark and partially girdled limbs are so 

 characteristic of this disease that it is easily recognized. (See Fig. 86.) 

 The diseased part may extend for several feet along the branch, or may 

 be only a small spot. Usually it is five to ten inches long. The bark 

 may be merely roughened and black (as in B, Fig. 86) or the limb may 

 be partially girdled (as in A, Fig. 86). In the worst cases the dead limbs 

 stick out all over the tree-top. (See Fig. 87.) 



Extent of the injury. The canker causes more loss than any other 

 disease except the scab fungus and, possibly, the fungi that cause the 

 trunks to decay when improperly pruned. It was found to be very serious 

 in 14 per cent of the orchards and was do-ing considerable damage in 

 19 per cent. Injuries of this character are less conspicuous but are much 

 more serious than those that affect the leaves canker attacks the tree 

 directly. It does not often do much damage on young trees. It usually 

 occurs on limbs two to three inches in diameter, but sometimes attacks 

 the twigs or larger limbs. It very rarely occurs on the trunks, except 

 on the Twenty Ounce. This variety is particularly subject to the disease. 

 I have seen very few mature Twenty Ounce trees that were not badly 

 infected. It is also serious on the Spitzenburg. The Baldwin is more 

 affected than the Greening, Russet, King or Northern Spy. 



The same fungus occurs on the leaves, but does not seem to be serious. 

 In Wayne county in 1903 it was found on the leaves in eight orchards 

 and was doing considerable damage in seven of them. It was not found 

 on the foliage of any orchard examined in 1904. On the leaf it shows 

 a distinct series of concentric circles. One infected point may develop 



