76 PRACTICAL TREE REPAIR 



attack the fruit. The apple blister canker {Nu- 

 mularia discreta) is one of the most destructive. 

 It is a wound parasite, starting growth wherever a 

 bit of dry wood presents itself. For a time it 

 grows in the heartwood, then spreads into the 

 bark, rapidly killing a large patch. The affected 

 area becomes brown, sunken, and blistered. In 

 a year or two the branch is girdled and killed. 

 Pruned orchards should be sprayed promptly with 

 a fungicide, and all large wounds should be 

 dressed with an antiseptic. Small branches which 

 are inoculated should be removed. On large 

 limbs the affected areas should be cut away with 

 a draw-shave, the wound being carefully dressed. 

 The man who is repairing trees must know the 

 apple bark rots. When he finds a tree seriously 

 affected by one of them he must not fuss with 

 cavities in the tree until the far more dangerous 

 bark rot is cleaned out. 



The chestnut bark disease is not unlike the 

 blister canker. The mycelium of the fungus 

 enters the bark through small wounds. It grows 

 in the bark and cambium, spreading until it girdles 

 the limb and starves the outlying parts. The 

 bark of the affected areas becomes light brown 

 and shrinks as it dries. This fungus is spreading 

 rapidly in the eastern states. Many of the state 

 forestry departments, as well as the National Gov- 

 ernment, have issued bulletins on the disease, di- 



