MAINE AGRICULTURAI, EXPERIMENT STATION. IQIO. 4O5 



epidermis. The spores of the fungus are formed inside these 

 bodies and escape through an opening at the apex. The ap- 

 pearance of an apple in this stage of the decay is shown in Fig. 

 69. There is only one other fungus (Phoma mali, see p. 408) 

 which in Maine causes a similar appearance of decayed apples 

 and the amount of loss caused by that fungus is small as com- 

 pared with the loss caused by Sphaeropsis. 



Since the fungus which causes the black rot of apples also 

 causes a disease of the wood and leaves, any means of control 

 of the rot must take into consideration these sources of infection 

 of the fruit. Old, diseased trees are almost certain to produce 

 Sphaeropsis spores in large numbers on dead and dying limbs 

 and these spores are ready to infect the apples as they mature 

 and to cause their decay. One good means of control then is to 

 remove the source of infection by cutting out and burning all 

 dead and diseased wood. All decayed fruit should also be 

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

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

 disease. 



Penicillium 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 more than one 

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

 cay but since Penicillium breaks out and shows more prominent- 

 ly on the surface of the apple, it is often held responsible for 

 more of the decay than it causes. There can be no doubt, how- 

 ever, that one or more species of PeniciUitim cause a large 

 amount of the soft rot of stored apples. This is primarily a rot 

 of ripe apples and does not cause decay of green fruit. The 

 threads of the fungus cannot penetrate the uninjured epidermis 

 of the apple 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 



