CHAPTER XIII. 



THE DISEASES OF FRUITS. 



FRUIT growing is frequently interfered with by various dis- 

 eases. So serious have these become in many instances that 

 considerable attention of late years has been paid to them by 

 the United States government and the various Experiment 

 Stations. It is the purpose in the following few pages to con- 

 sider the leading diseases of those fruits that are described 

 under their separate heads in subsequent pages of this book. 



By way of introduction, it may be stated that these diseases 

 are generally due to very small plants known as fungi that 

 prey upon the substance of leaf, flower, stem, or root, and 

 thus check the activity of the parts or destroy them alto- 

 gether. These fungi are, perhaps, best known to the people 

 generally in the conspicuous forms they assume as toadstools, 

 puff-balls, and the various hard shelf-like outgrowths often 

 seen upon the trunks of standing trees or fallen logs. Those 

 forms that are charged with doing injury to crop plants are 

 so small as to be entirely microscopic. The mould that comes 

 upon bread when left too long in a moist, warm place is more 

 like the destructive fungi of the orchard and fruit garden than 

 the mushroom or toadstool. These fungi consist of very 

 slender threads, which absorb nourishment from the substance 

 they penetrate and reproduce their kind by means of minute 

 bodies that are usually produced in great abundance. These 

 spores bear the same relation to the fungus that seeds do to 

 flowering plants ; they are, in short, the offspring, and being 

 microscopic, their distribution, chiefly through the moving 

 air and flowing water, takes place unobserved by men. 



These fungi are creatures of circumstance, and the spores 

 do not germinate and grow unless there is the proper food at 

 hand and moisture and warmth abound. It is during the 

 moist warm days of August, for example, that the provisions 



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