^6 STATE POMOLOGICAL SOCIETY. 



APPLE SCAB OR BLACK SPOT FUISICLADIUM DENDRITICUM. 



Attention has been called to this fungus parasite as doing con- 

 siderable damage to apples in the State. Apples marketed in Orono 

 and Bangor have been examined and the disease found to be com- 

 mon in this region. We also learn that it is prevalent in other por- 

 tions of the State. The disease is widespread over the country, 

 destroying in some of the states annually' from one-half to one- 

 sixth of the crop. 



This fungus attacks the twigs, buds, leaves and fruits, but is most 

 noticeable on the fruit, appearing as olive green spots, with a circular 

 outline, which become velvety as they get older. When the fungus 

 attacks the twigs and leaves it affects the vitalit}' of the tree. The 

 greatest injury is done to the fruit, the marketable product. An 

 early attack causes the fruit to shrivel and drop — a later attack pro- 

 duces a withered stunted growth. A late attack upon the full 

 grown fruit discolors its surface and depreciates its marketable value, 

 making it liable to rot under the scab spots when stored. The dis- 

 ease is worse in damp, cold seasons. It starts in the spring from 

 spores that have lived over winter, or from the plant bodj', which has 

 retained its vitality in the twigs, fruit or fallen leaves. The cold, 

 damp, spring weather causes a rapid growth of spores, which estab- 

 lish themselves upon the young fruit and leaves. The warm, dry, 

 summer weather arrests the growth, which is continued again during 

 the damp, cooler, autumn months. The fungus shows some preference 

 for certain varieties, but in bad seasons all are more or less affected. 

 The parasite has a wonderful vitalit}' and the plant body is probabl}' 

 perennial. We have now, January, apples covered with the fun- 

 gus in a vigorous growing condition. Specimens apparently dead 

 when taken from the barrel, kept moist a few days, begin growth. 

 It has been shown that the spores will germinate in about eight 

 hours at the low temperature of 50° F., insuring an early start 

 in the spring. 



The successful treatment of this disease may be regarded as an 

 open question, but on account of the annual injury done it should be 

 carefully studied. The station will conduct some experiments next 

 season upon this disease and will be pleased to correspond with 

 orchardists in different parts of the State where the disease was bad 

 the past season, and cooperate with them. 



