CHAPTER XXVI. 



NECROTIC DISEASES. 



Patches Frost-patches Bruising due to hail, shot, etc. 

 Fire Sun-burn or scorching Suti-cracks. Dying- 

 back Frost Fu7igi Wound fu7igi Defoliation by 

 ifisects Defoliation by hand Staghead. 



Necrosis. This is a general term for cases where 

 the tissues gradually turn brown or black in patches 

 which die and dry up, the dead area sometimes 

 spreading slowly and invading the usually sharply 

 demarcated healthy tissues around. It is a com- 

 mon phenomenon on the more slender stems or 

 branches of trees, especially those with a thin 

 cortex, and the terms Brand or ScorcJiing some- 

 times applied signify the recognised resemblance 

 between burnt patches and these dead areas of 

 necrotic tissue. 



Necrosis is often due to frost, which kills the 

 cortex of Pears, Beech, etc., in patches of this kind. 

 The dead cortex and cambium stick to the wood 

 beneath and contract as they dr)-. The living 



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