MAEKET DISEASES OF APPLES, PEAKS, QUINCES H 



and curls up in thin papery brown flakes or rolls. During the first 

 season, or sometimes not until the second season, cankered areas show 

 numerous pycnidia (the spore-producing pustules of the fungus) 

 like those already described on the fruit. 



Under favorable temperature conditions, 50° F. or higher, rotting 

 of the fruit takes place in the orchard, in transit, in storage, and on 

 the market. It does not ordinarily spread from one fruit to another. 



Ripe fruit is more likely to be attacked than green fruit. Infec- 

 tion may take place at injured places in the skin, such as worm holes, 

 bruises, limb rubs, and hail injury, in all of which the rot develops 

 freely if conditions are favorable, and finally involves the whole 

 fruit. Infection may also follow spray or frost injury at the blossom 

 end, producing what is known as blossom-end rot. The rot may 

 develop steadily from the time of infection and finally involve the 

 whole apple, or it may progress for a short time, then become quies- 

 cent, only to start up again when conditions are more favorable, as, 

 for example, when the fruit is barreled and shipped to market with- 

 out refrigeration. 



CONTROL MEASURES 



Cutting out diseased limbs and twigs and cleaning and painting 

 the cankers gives fairly good control, but only in proportion to the 

 thoroughness with which it is done. The leaf spot can usually be 

 controlled by the sprayings recommended for apple scab. Control 

 of the fruit rot depends primarily on the elimination of cankers 

 from the trees, the prevention of mechanical injuries to the fruit, 

 and the maintenance of temperatures in storage and in transit that 

 are unfavorable to the growth of the fungus. (i7, 22^ 4^, 53^ 100 1 

 110^ 111, im, lis, lU, 195, 208, 209, 221^ 222, 2J^2.) 



BLOTCH 



(Phi/llosticta soUtaria Ell. and Ey.) 



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 common and most destructive in Kansas, Arkan- 

 sas, and the southern portions of Missouri, Indiana, Illinois, and 

 Ohio. The most susceptible varieties of commercial importance are 

 Ben Davis, Northwestern Greening, Missouri Pippin, Oldenburg 

 (Duchess of Oldenburg), and Wagener. 



Blotch spots on the fruit are characterized by fan-shaped areas 

 with fringed margins grouped around a common center, the diameter 

 of the spots varying from one fourth to one half inch or more 

 (pi. 4, C). The spots are light brown and superficial at first but 

 later become nearly black and markedly sunken; the small black 

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

 the blotch spot becomes visible. On Ben Davis and Missouri Pippin 

 and sometimes on other varieties cracks occur in the older spots 

 that often intersect in the form of a cross or a Y. 



Most of the damage to fruit occurs late in June, the particular 

 time varying somewhat with the variety and with the weather during 



