DISEASES INJURIOUS TO FRUITS. 



81 



Remedy. The remedy for this is Bordeaux mixture applied 

 just before the flowers open in the spring and two to four ap- 

 plications of it later at intervals of about two weeks. 



Black Rot (Sphaeropsis malorum).^ihis disease often 

 causes serious rotting of the quince just before maturity. It 

 generally starts from the calyx end. The remedy is a preven- 

 tive, and consists of spraying with Bordeaux mixture. 



Diseases of the Plum. 



Plum Pocket (Exoascus pruni). This is a name given to 

 certain peculiar deformities which occasionally take the place 

 of plums on the trees. They consist merely of a thin shell with 

 no evidence whatever of seed. They appear in early summer, 

 and some seasons this disease is very abundant and then for 

 a number of years it may scarcely appear at all. It is due to 

 the presence of a parasitic fungus which attacks the young 



fruit, and by growing with- 

 in it causes the peculiar de- 

 velopment which finally re- 

 sults in the formation of the 

 so-called pocket. This, or a 

 similar fungus, may also at- 

 tack the foliage and cause 

 irregular swellings and dis- 

 tortion. 



Remedies. It will some- 

 times be found that a sin- 

 gle tree will be troubled 

 with this fungus for a se- 

 ries of years and it will not 

 spread much. When this is 

 the case such trees should 

 be destroyed, as they are 

 likely to be centers of in- 

 fection, and the diseased fruit should be picked and destroyed. 

 Some varieties are more subject to its attack than others. 



The leaf curl of peaches is caused by a fungus similar to 

 that which causes plum pockets and recent experiments show 

 that this disease may be kept in check by spraying with thick 

 Bordeaux mixture or a solution of sulfate of copper just be- 



Fig. 33. Leaf curl of plums in- 

 volving twig and foliage. 



