324 The Principles of Fruit-growing 



around the edges, showing that the difficulty 

 probably affects the entire leaf and not any one 

 part of it. In general, there is a tendency for 

 foliage in plants so attacked to wither and hang 

 on the tree for a time. The peach yellows and 

 pear blight are diseases of this kind. There are 

 no specific treatments for these troubles. They 

 must be approached by what physicians call 

 prophylaxis, — that is, by methods of sanitation 

 and prevention, and by eradication of the parts. 

 The diseased plants or parts are cut away and 

 burned. All conditions that seem to favor the 

 development of the disease are removed. Varie- 

 ties particularly susceptible are discarded. Care- 

 ful management is often much more important 

 than any attempt at specific treatment. 



SPECIFIC EBMAEKS ON SPRAYING 



1. Spraying is only one of the requisites to success in 

 fruitHraising. — Trees must grow before they can bear, 

 and this growth depends on food and proper conditions 

 of soil, more than it does on the accident of im- 

 munity from insects and fungi. It is one of the cardinal 

 operations for which the grower must plan in the 

 beginning. 



2. Spraying is insurance. — There are many elements 

 of risk in the growing of fruit. It is impossible to foretell 

 by any considerable length of time whether any or all of 

 the difficulties liable to harass the fruit-raiser will 

 actually appear. The owner does not know whether his 

 buildings will bum, yet he insures them. We know that, in 

 four years out of five, some damaging injury of insects or 



