404 AGRICULTURE 0? MAINE. 



FRUIT DECAYS. 



During the past 3 years this laboratory has devoted consider- 

 able attention to a study of the fungi which cause decay of ap- 

 ples in Maine. Fungi have been isolated from decaying apples 

 from various places and these have been tested by means of in- 

 oculations in order to determine the extent to which each was 

 capable of causing decay. It has been found that Maine has a 

 considerable number of the apple decay fungi which have been 

 described from other places but the relative amount of rot 

 caused by some of these fungi under local conditions diflfers ma- 

 terially from the amount attributed to the same fungi in other 

 parts of the United States. For example the "bitter rot" fun- 

 gus while it occurs here does very little damage in comparison 

 with the amount of loss resulting from its attacks in other sec- 

 tions. The apple decays which have been found in Maine will 

 be described in the following pages together with the means of 

 control so far as these measures are understood. 



Black rot. This rot is caused by Sphacropsis malorum Pk. 

 which also causes a decay of pear and quince. The fungus at- 

 tacks apples both on the tree and in storage and is responsible 

 for much of the rot on the trees in this State. It is capable of 

 causing decay of green fruit but its progress is much more 

 rapid in apples which are ripe or nearly ripe. Early apples are 

 especially susceptible. As a cause of storage decay, Sphacrop- 

 sis probably ranks second to Penicillium which is described be- 

 low. On account of the relation to leaf-spot, and limb-cankers 

 as well, the black rot fungus in distribution and economic im- 

 portance probably ranks second in the State to that which causes 

 apple scab. 



Black rot of the apple takes its name from the appearance of 

 the fruit in the late stages of the decay. In early stages, the 

 decayed region is brown in color but the mycelium of the fungus 

 takes on a dark color with age and thus colors the apple. The 

 fungus usually enters the apple at either the blossom or stem 

 end, and, if the temperature is favorable for growth, spreads 

 rapidly and causes the complete decay. The decaying region is 

 marked by concentric rings. When the mycelium has grown 

 in the apple for a sufficient length of time the threads begin to 

 form little aggregations just beneath the epidermis which de- 

 velop into the small black bodies which later break through the 



