DISEASES 223 



thus formed, though usually about I inch long, may girdle the fruit 

 and extend to the core. The cracks often intersect, forming a cross. 

 The character of the spots is not always the same on the different 

 varieties. There are all variations, from the quite large, much 

 fringed, and smooth spots on the Missouri variety to the small, 

 compact, and often umbonate spots on the Limbertwig. An 

 occasional spot somewhat rectangular in shape may be decidedly 

 sunken and quite black, with a definite margin. 



Within a few days after the spots become visible, black pycnidia 

 begin to develop on the diseased areas. Three, four, or many more 

 occur on each spot, and are scattered promiscuously or grouped on 

 a small blister cracked around the margin. 



The general effect of the blotches on the fruit is to mar its ap- 

 pearance and render it unfit for packing. Moderately affected fruit, 

 especially if not badly cracked, may be evaporated, but much of it 

 cannot be used even for this purpose because of the difficulty of 

 paring, and is a total loss except where it can be used for vinegar. 

 A large percentage of the affected fruit drops prematurely and 

 unless utilized immediately is a total loss. 



Bitter rot (Glomerella rufomaculans, Berk, and Sp. & Von Sen.). 

 Of all diseases of the apple, bitter rot is one of those most to be 

 feared and fought. It is the most insidious because of its erratic 

 behavior. It appears with great suddenness, laying waste in a 

 few days or weeks all the careful work of the orchardist. Few, 

 if any, advance notices of its appearances are served, and the only 

 effective campaign that can be waged against it is that of preven- 

 tion. Once well started, an outbreak can at best only be checked. 

 The fact that the disease does not appear to a destructive extent in 

 successive years and that the outbreaks come without warning makes 

 the grower feel inclined to take a chance at its nonappearance and 

 to dispense with preventive sprayings. This " gambling," however, 

 often results in a loss of all or a large part of the apple crop. It is 

 always the part of economy to prepare each year for the possible 

 appearance of the rot. It should be mentioned, however, that some 

 varieties are much more susceptible to this disease than others, 

 two of those which show little resistance being the Ben Davis and 

 the Shockley. Many other varieties can be easily determined by 

 investigating in the orchard. 



