94 DISEASES OF ECONOMIC PLANTS 



West Virginia. The use of ammoniacal copper carbonate 

 as the leaves unfold, and continued at intervals of two 

 weeks until budding time, will usually prevent damage from 

 the disease. Sulphur or sulphide sprays have given best 

 results in dry climates. 



Podosphaerose (Podosphcera leucotrichia (Ell. & Ev.) 

 Salm.). — This mildew is similar to Sphaerothecose. 



Crown gall. — See peach. 



Soft rot, bin rot, blue mold {Penicillium glaucum Link). 

 — Perhaps the most common apple rot is found upon 

 stored apples late in the year. The light tan-colored 

 rotten area is soft and watery. The decay results in the 

 complete loss of the affected fruit, and, by contagion, in 

 loss to the fruit mass. 



Upon cracks in the rotted surface, and eventually over 

 the whole rotten part, appear tufts of very short delicate 

 fungous threads, at first white, soon bluish green, very like 

 the common blue mold so familiar to the housewife upon 

 canned fruit, the seal of which has permitted air to enter. 

 This blue substance upon the rotten apple consists of 

 myriads of the spores of the causal fungus. This fungus 

 is comparatively unaggressive and cannot force its way 

 into perfectly healthy tissue; a bruise or rupture of the 

 skin is necessary to its invasion. The best preventive 

 is care to avoid bruising. 



Sooty blotch {Phyllachora pomigena (Schw.) Sacc). — 

 Irregular, sooty, black blotches, especially conspicuous 

 on the lighter colored varieties, are frequently seen upon 

 unsprayed fruit. 



The individual blotches measure from 0.5-2 cm. across 

 and are often so abundant that they coalesce, giving the 



