MAINE APPLE DISEASES. 34I 



used up considerable of the available food material and throws 

 out fruiting organs on the surface. 



Those fungi and bacteria which are able to attack living 

 bodies are said to be parasitic or parasites. Those which secure 

 their nourishment from dead organic matter are designated as 

 saprophytic or saprophytes. The saprophytes far outnumber 

 the parasites and the majority of them cannot under any con- 

 dition cause disease. However, there is no hard and fast line 

 between the two classes. Some fungi which ordinarily live as 

 saprophytes may, under favorable conditions, attack and destroy 

 living plant tissues. Some fungi are obligate parasites but a 

 large number of the disease producing forms are capable of a 

 saprophytic mode of existence as is shown by the fact that they 

 may be successfully grown upon a variety of artificial culture 

 media. This fact is of great importance to the orchardist. 

 Dead limbs, piles of rubbish and rotted fruit which frequently 

 are allowed to accumulate in the orchard are breeding centers 

 for those fungi which attack the fruit, leaves, and wood of the 

 tree. Hence the first step in removing the cause of disease is 

 thorough orchard sanitation. 



Non-parasitic Diseases. 



Winter Injury. Those parts of Europe and Asia where the 

 apple is native have very moderate rainfall and are not subject 

 to such wide range and abrupt changes of temperature as in 

 this State. The northern limit of range of the apple except in 

 the case of the very hardy varieties is determined approximately 

 by the lowest winter temperatures, or — 30° to — 32° F., re- 

 peated at frequent intervals. Some varieties, like the Baldwin 

 and Ben Davis, in Maine apparently arc liable to be injured 

 where the repeated minimum winter temperatures are several 

 degrees warmer than this. 



Other conditions also enter into winter killing, such as defi- 

 cient rainfall in spring and early summer followed by a late 

 fall, thus preventing early growth, maturity and ripening of the 

 season's wood. Similarly too, late cultivation and the applica- 

 tion of large amounts of fertilizer rich in nitrogen may also 

 stimulate to late growth and prevent ripening of the wood before 

 cold weather comes on. and predispose to winter injury. The 

 amount of moisture whicli the ])lant cells contain at the time 



