XIII 



OTHER TROUBLES 



Spraying is not exactly a universal reliance in the 

 care of fruit trees, for the reason that there are some 

 sorts of damage caused by other agencies than fungi 

 and insects. A few words on the more common 

 troubles should be entered here. 



Blight — Fire blight, or twig blight, is a disease of 

 bacterial origin ; and as the bacteria which cause all the 

 trouble circulate in the sap of the tree they cannot be 

 reached by sprays. These bacteria are carried from tree 

 to tree by various insects, sometimes by bees ; but there 

 seems to be no practicable way of preventing their dis- 

 semination. It is well known that the blight is 

 worst on young trees, making a rank, soft growth ; 

 and this fact suggests a preventive in such forms 

 of culture and fertilizing as do not produce rank 

 growth. Where blight is bad it may be best to 

 stop the cultivation of the orchard for a year or 

 two. The free use of nitrogenous fertilizers, such 

 as barnyard manure, which is seldom to be recom- 

 mended, is especially to be discouraged in times 

 when blight is prevalent. 



The weather has a striking influence on the develop- 

 ment of the blight. Hot, moist, muggy weather in July 

 or August is always favorable to it. At such times the 

 new growth will be struck and withered in a day or 

 two. leaving the tree burnt and blackened as though 

 burnt over by a scorching fire. Hence the name fire 

 blight. 



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