MAINE APPLE DISEASES. 363 



dead and diseased wood. All decayed fruit should also be de- 

 stroyed. If this is followed by the spraying which is recom- 

 mended for apple scab it will go far toward the control of this 

 disease. 



Pcnicillium or blue mold decay. This is the rot of apples 

 which is caused by the common blue mold which is familiar to 

 every one on preserved fruits, jellies, etc. Blue mold grows as 

 a saprophyte on a large number of dead organic substances and 

 produces large numbers of spores so that the spores are prac- 

 tically everywhere present and may start a new growth of the 

 mold whenever they fall upon a substance which furnishes a 

 suitable food supply provided that the temperature is favorable 

 for growth. It is a widespread cause of decay in Maine, es- 

 pecially where the fruit has not been carefully handled. 



This decay of apples is probably caused by mure than one 

 species of this genus. In some cases other fungi aid in the decay 

 but since PeniciUium breaks out and shows more prominently on 

 the surface of the apple, it is often held responsible for more of 

 the decay than it causes. There can be no doubt, however, that 

 one or more species of PeniciUium cause a large amount of the 

 soft rot of stored apples. This is primarily a rot of ripe ap])les 

 and does not cause decay of ^reen fruit. The threads of tlie 

 fungus cannot penetrate the uninjured ejiidermis of the api)le but 

 must gain entrance through injured places such as bruises, cuts, 

 cracks, worm holes, spray injured places or scab spots. It 

 spreads rapidly in ripe apples and complete decay takes place in 

 one to two weeks. The tissues become soft and are light brown 

 in color. Little tufts of mycelium which bear the s])ores break 

 out on the surface of the decayed region as shown in Fig. 231. 

 These tufts soon become light blue or blue-green, later gray- 

 green to brownish in color. Ap]:)les rotted by PeniciUium take 

 on a characteristic moldy odor and taste. 



Since the fungus enters the apple through wounds, any means 

 of control of the rot must look to the prevention of injuries to 

 the epidermis. Care must be taken to produce good, sound ap- 

 ples and then these should be picked and handled in such a way 

 as to avoid cuts and bruises. The apples should be stored where 

 the temperatures are as low as can be maintained with safety 

 from freezing. 



Bitter rot. This disease which does so much damage in some 



