90 



Chapter VII. 

 DISEASES OF THE APPLE IN MASSACHUSETTS. 



A. VINCEXT OSMUX, PEOFESSOK OP BOTANY, MASSACHUSETTS AGRICUL- 

 TURAL COLLEGE. 



The enormous development of the apple-growing industry 

 in this country during the last two decades has brought in- 

 creasing competition, and growers have come to realize that 

 their business must stand or fall on the quality of the fruit 

 they produce. Only clean fruit, that is, fruit free from blem- 

 ishes caused by insects or diseases, can meet the competition 

 and market demands. An added incentive to the production 

 of clean fruit is fiu-nished by the new State law to regulate the 

 grading and packing of apples. And surely every real wide- 

 awake apple grower takes pride in producing clean, high-class 

 fruit, regardless of regulatory laws. Naturally, the grower 

 who is interested in the quality of fruit which he grows wishes 

 to know something about the diseases which he is forced to 

 combat. 



Diseases of the apple are of two sorts: (1) those caused by 

 microscopic organisms (fungi and bacteria); and (2) those due 

 to unfavorable weather, or cultural conditions, or functional 

 disorders. The first group are known as parasitic diseases 

 and the second group are called nonparasitic or physiological 

 diseases. 



Parasitic diseases are caused by bacteria or fungi growing 

 and feeding on the surface or in the tissues of the host, and 

 specific organisms may attack root, trunk, twigs, leaves or 

 fruit, thus bringing about a diseased condition. 



Where the causal organism of a disease is known, a remedy 

 for the disease, based on control of the organism, can usually 

 be worked out. In fact, every grower should understand that 

 intelligent attack on any parasitic disease must have back of 



