432 ■ State Horticultural Society. 



winter stage. The fungus thrives best during cool, moist weather, and 

 upon closely crowded trees from which air and light are shut out. 



Before the buds open the tree should be sprayed with a strong so- 

 lution of copper sulphate. Bordeaux should be used just before and 

 after blossoming, .and several times afterwards at intervals of two or 

 three weeks. The trees should not be crowded, and all the dead rubbish 

 should be burned, and the ground plowed. 



APPLE CANKER. BLACK ROT. 



Sphaeropsis malorum Pk. 



The apple canker and black rot are two very common orchard dis- 

 eases, caused by the same fungus. The former attacks the stems and 

 branches of the apple tree, while the latter attacks its fruit and leaves. 



The black rot attacks summer apples at the time of ripening, and 

 fall and winter apples after storage. Green apples are rarely attacked, 

 except when injured by insects or otherwise. Windfall apples are very 

 susceptible to the disease. Apples affected by this fungus first turn 

 brown, then black. They lose their firmness and dry out, becoming 

 much wrinkled and shrunken. Beneath the epidermis small black dots 

 or cups appear. These dots contain many spores, which escape through 

 a small opening into the air. 



These black dots can also be seen upon twigs which have been at- 

 tacked. 



Upon the leaves the fungus forms roundish or irregular dark 

 brown spots. They may become so numerous as to cause the leaves to 

 die and fall. 



The pear and quince are also attacked by this fungus, causing the 

 same appearance upon them. 



The treatment for the black rot is the same as that given for the 

 scab. The fungus, in attacking the stems and branches, forms large 

 cankers. These appear in the early spring as discolored areas on the 

 bark. The areas enlarge, killing the inner bark ; the limb becomes 

 swollen and the bark rough and dark colored. The wood may become 

 exposed. The cankers cause an interference with the circulation of the 

 sap, and they either kill or weaken the branch accordingly, as they 

 either v^rholly or only partially girdle it. Cankers are also formed on 

 pear trees by the fungus. All cankered limbs should be removed and 

 burned. Cankers on very large limbs may be cut out and the wounds 

 painted over with some paint or wash. The branches should be sprayed 

 when spraying for other diseases. 



