THE APPLE 



summer rot of the fruit. Infections of the tree doubtless have their 

 origin in the spores given off by the fruit, while, on the other hand, 

 it is equally reasonable to assume that the canker is the means of 

 infecting subsequent crops. 



Control measures are to prune out all limbs showing canker, 

 and spray the tree with Bordeaux mixture or lime-sulphur from 



two to four times during 

 the season. 



Black rot and canker 

 (Sphceropsis malorum). Of 

 late much damage has 

 been done by this canker. 

 It was first studied in 

 New York State, and has 

 since been known as " the 

 New York apple canker." 

 However, it has been 

 found in other sections of 

 the country, notably in the 

 northeastern and north- 

 central states, as well as in 

 Canada, and probably in 

 all apple-growing regions. 

 Its presence is indicated 

 by a swollen appearance 

 of the limb and a very 

 rough and depressed bark, 

 with sometimes an expo- 

 sure of the wood in the 

 center of the affected part. 

 Often the affected area 

 extends several feet along the bark, while in its mild form the 

 canker may be merely a spot. Small twigs and the trunks are 

 sometimes affected, but the disease most often occurs on the larger 

 limbs of the older trees. Young trees are occasionally infected, 

 the result often being a complete girdling of the tree, and death. 

 From the available data it is evident that the most serious 

 damage by this rot is only on limbs which have received wounds 



Fig. 93. Stages in the formation of Sphasropsis 

 limb cankers. (University of Maine) 



