SOME OF OUR MOST COMMON APPLE DISEASES 



861 



spraying in the control of apple scab. A mixture of eighty or 

 ninety parts sulphur to ten or twenty parts powdered lead is to 

 l>c regarded as most effective. Applications are to be made at 

 the same time as recommended for spraying. 



BLACK ROT, LEAK SPOT AM) CA.XKKK OF THE APPLE 



r l'h is disease which is caused by the 

 fungus Physalospora cydonice, is per- 

 haps best known to Xew York 

 farmers under the name " Xew 

 York apple-tree canker." Tho above 

 designation is assigned and used 

 to represent more nearly the nature 

 of the trouble in its attacks on the va- 

 rious parts of the apple. The fungus 

 not only produces on the limbs a serious 

 canker, but it also affects the fruit, in- 

 ducing a black rot, and attacks the 

 foliage, producing a leaf spot. These 

 three forms of the trouble are not every- 

 where equally troublesome ; in this state 

 the limb injury is the most familiar 

 and also the most dangerous type of 

 this disease. Prominent growers and 

 scientists concur in the opinion that tht 

 Xew York apple tree canker is, in cer- 

 tain parts of the state at least, second 

 in economic importance only to the 

 apple scab. 



As previously stated, the canker is 

 caused by a fungus. It may live about 

 the orchard on dead twigs in the brush 

 pile, or it may feed on the dead parts 



<5f a great variety of wild and cultivated trees and shrubs. 

 The spores of the fungus may be present for a time on the 

 healthy bark and may even prepare to enter the bark, but 

 actual penetration is never accomplished until an injury of 

 some sort is afforded. The fungus does not seem to have prefer- 

 ence in this re.spect, for it follows frost injury, fire blight, apple 



FIG. 240. BLACK ROT 

 CANKER ON APPLE LIMB. 

 NOTICE THE PIMPLE-LIKE 

 FRUIT BODIES COVERING 

 THE CANKERED SURFACE 



