MARKET DISEASES OF FRUITS AND VEGETABLES 15 



to market without refrigeration. Black rot extends into the fruit 

 very rapidly, often reaching the core when the rotten spot on 

 the surface is only 1 or 2 inches across. 



CONTROL MEASURES 



The sprays applied for the control of apple scab will usually 

 prevent the leaf spot phase of the disease. Control of black rot on 

 the fruit depends primarily on elimination of deadwood through 

 proper pruning. Prevention of insect and mechanical injuries to 

 the fruit and maintenance of temperatures in storage and in 

 transit that are unfavorable to the growth of the fungus aid in 

 reducing decay. 



(See 11, 12, 59, 6U t 65, 1U, 128, US.) 



Blotch 



(Phyllosticta solitaria Ell. & Ev.) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Blotch occurs in the territory extending west from southern 

 New York to southern Iowa and South Dakota and south to 

 Georgia and Texas. It is most apt to be destructive in Kansas, 

 Arkansas, and the southern parts of Missouri, Indiana, Illinois, 

 and Ohio. The disease occurs in varying degrees of severity on 

 Mcintosh, Maiden Blush, Northwestern Greening, Rome Beauty, 

 Yellow Newtown, and Yellow Transparent. It is rarely seen on 

 Delicious, Grimes Golden, Jonathan, Stayman, and York Imperial. 



Blotch spots on the fruit are characteristically fan-shaped areas 

 with fringed margins grouped around a common center, the diam- 

 eter of the spots varying from % to !/2 inch or even more (pi. 1, 

 E). The spots are light brown and superficial at first, but later 

 they become nearly black and markedly sunken. The small black 

 fruiting bodies (pycnidia) begin to appear within a few days 

 after a blotch spot becomes visible. Toward harvesttime cracks 

 occur in the older spots and render the fruit worthless. 



Most of the fruit infections occur before the end of June, the 

 particular time varying somewhat with the variety and with the 

 weather during the growing season. Much of the badly diseased 

 fruit drops before picking time. That which arrives on the mar- 

 ket suffers seriously from the disfiguring effect of the blotch 

 spots and occasionally also from rots resulting from secondary 

 fungus infection. Blue mold and the black rot fungus are most 

 commonly found associated with blotch in this way. 



CAUSAL FACTORS 



Blotch is caused by the fungus Phyllosticta solitaria, which 

 attacks the leaves, fruit spurs, and twigs of the apple. From the 

 last two infection spreads in the spring to other parts of the tree. 



CONTROL MEASURES 



In orchards where the disease has been destructive, blotch can 

 be controlled by spraying three times at 3-week intervals, begin- 

 ning about 3 weeks after the petals fall. The recommendations 

 of the local agricultural experiment station regarding materials 

 to be used should be followed. 



(See 12, 59, 65, 112, 1U.) 



