MARKET DISEASES OF APPLES, PEARS, QUINCES 43 



orchard is very late, they may appear after several months of storage. 

 Such spots vary in diameter from one sixteenth to one quarter of an 

 inch. They are circular, darker in color than the field lesions, and 

 have definite smooth borders (pi. 3, B). 



Often the cuticle above the spot is not broken and the surface is 

 shiny, dark brown to jet black, although it is usually roughened by 

 the pressure of the mycelium beneath. Such spots, on account of 

 their color, are sometimes confused with blotch. They can be dis- 

 tinguished from it, however, by the fact that no fruiting bodies are 

 developed and by the further fact that the edges of the spots never 

 show the marked feathery fringed appearance characteristic of the 

 early stages of blotch. On overripe fruit the lesions may enlarge 

 rapidly. The high humidity and temperature found in common 

 storage also favor development of the disease. 



CONTROL MEASURES 



Spray schedules for scab vary considerably in different parts of 

 the country. Under ordinary conditions in most regions the disease 

 can be controlled by applications of lime-sulphur (either the com- 

 mercial liquid or the commercial powdered form) for the prepink 

 and the pink sprays, and again just after the petals fall, followed 

 in about 10 days and again late in July or early in August by appli- 

 cations of lime-sulphur or sulphur dusts. In some sections Bordeaux 

 mixture is substituted for lime-sulphur in the summer applications 

 to avoid injury to the fruit from sulphur sprays applied in hot 

 weather. 



It is also advisable to rake and burn the dead leaves or to plow 

 them under some time before the growing season begins, though such 

 a procedure should never be considered as more than merely supple- 

 mentary to spraying. (^, 10, m, SI, ^7, 63, 5Jf, 65, 62, 71, 76, 100, 106, 

 llJf, 120, 123, 12Jf, 130, llfl, 176, 183, 192, 196, 202, 208, 209, 210, 220, 

 22 J^, 2S2, 237.) 



SCALD 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Scald is one of the most serious storage and transportation diseases 

 of the apple and occurs on fruit from all producing sections of the 

 country. No variety is entirely immune, but there is a wide variation 

 in susceptibility. Among the varieties most seriously affected are 

 York Imperial, Grimes Golden, Arkansas (Mammoth Black Twig), 

 Rome Beauty, Rhode Island Greening, Baldwin, Wagener, Stayman 

 Winesap, Yellow Newtown, and Winesap. 



Scald is a disease that affects chiefly the skin of the apple and is 

 confined largely to the greener side (pi. 5, B). Bright-red fruit 

 areas are rarely affected. In mild cases the disease appears as a 

 mere superficial browning of the skin, but in more severe cases the 

 entire skin layer is killed and sometimes broken down to the extent 

 that it will slough off readily from the underlying tissue. In some 

 instances the flesh of the apple becomes dead and brown to a depth 

 of a fourth of an inch or more and has much the appearance of a 

 rot ; but true rots usually spread down into the flesh in more or less 

 conical shape, while scald is diffuse. 



