THE PLUM IN KANSAS. 127 



OTHER PLUM-TREE DISEASES. 



From Bulletin No. 92, North Carolina Experiment Station. 

 POCKETS OR BLADDERS. 



Plum pockets, or plum bladders, as it is indifiPerently called, is a 

 disease produced by a fungous parasite. This disease is probably of 

 foreign origin, but is now naturalized in America wherever the plum 

 is grown. It attacks the light-colored plums with greatest virulence. 

 The Wild Goose and Marianna are especially susceptible, but the 

 Japanese varieties seem exempt so far. The disease attacks the leaves 

 and branches, also producing a sort of blight very similar in appear- 

 ance to the blight of peach twigs, which is, however, caused by a 

 different fungus. On the fruit it causes the recently formed plums 

 to swell out and become hollow, producing what are aptly called 

 bladders. Such fruits soon fall to the ground. The spores of the 

 fungus pass the winter in the diseased twigs and probably also upon 

 the remnants of the rotten fruit on the ground and in the fallen leaves. 



Remedies: Collect and burn all leaves as soon as possible after they have 

 fallen. Cut back severely all branches or twigs which have borne diseased fruit, 

 or which show the blight-like blackening. Early in spring, as soon as the flower- 

 buds begin to burst, sprinkle the ground under the trees with air-slaked lime. 

 Spray before the buds start with the Bordeaux or copper sulphate mixtures di- 

 luted one-third more than the formula gives. 



SHOT-HOLE DISEASE, 



Like the other stone fruits, the plum is subject to a fungous leaf 

 parasite which produces small black spots, which soon wither and fall 

 away, leaving the leaf full of small, round holes, sometimes called 

 "shot holes." The fungus passes the winter in the fallen leaves of the 

 preceding year. It does not attack the fruit or twigs. 



Remedies : Rake up and burn all leaves as soon as they fall. In spring spray 

 with diluted Bordeaux or sulphate mixtures as soon as the leaves are one-half 

 grown, and repeat in two weeks. Usually two treatments will be sufficient. 



POWDERY MILDEW. 



This fungus works entirely on the surface of the leaves, drawing 

 its nourishment from the cells by means of minute suckers called 

 haustoria. Badly affected leaves appear as if dusted with a white 

 powder and this suggested the common name. The fungus does not 

 usually appear until late in summer. 



Remedies: Being on the surface, it is easily reached by any of the fungicides 

 in common use. Finely powdered sulphur, which has been successfully used in 

 combating the closely related powdery mildew of the grape, would probably be 

 equally effective in destroying this parasite. 



