MAEKET DISEASES OF APPLES, PEAKS, QUINCES 7 



control promises to be of considerable importance in the handling of 

 fruit to meet quarantine requirements relative to the shipment of 

 infested fruit. (4, S7, 38, 73, 7^, 176, m, 201.) 



BITTER PIT 



Bitter pit occurs in all the " important apple-growing regions of 

 the world. In the United States it may be found on practically 

 all varieties of apples but is of commercial importance on only a 

 few of these. The Baldwin, Northern Spy, Rhode Island Greening, 

 Grimes Golden, Tompkins King, Yellow Newtown, York Imperial, 

 Ben Davis, Rome Beauty, Winter Banana, Stayman Winesap, 

 Arkansas (Mammoth Black Twig), Arkansas Black, Delicious, and 

 Gravenstein are among the more susceptible varieties. 



In its usual form the disease is characterized by sunken spots 

 about one sixteenth to one eighth of an inch in diameter, distributed 

 over the blossom half of the apple. The spots resemble small bruises 

 and are sometimes wrongly ascribed to hail injury. In the early 

 stages they have a water-soaked appearance, but later they become 

 more highly colored than the surrounding fruit surfaces, taking a 

 deep-red color when on a blush area and retaining a bright green 

 when on a green or a yellow fruit surface. They finally become 

 brown or gray or sometimes black and are somewhat sunken (pi. 5, 

 E). When the apple is peeled or cut, numerous spots and streaks 

 of brown spongy tissue become evident just beneath the skin (pi. 6, 

 A). These spots, though closely associated with the water-con- 

 ducting system of the apple, are not confined to the region immedi- 

 ately beneath the skin, but may occur deep in the flesh. Contrary 

 to the implication in the name bitter pit, affected tissues are rarely 

 bitter. 



On apples of the Yellow Newtown variety the spots may occur 

 more on the cheek of the fruit than on the blossom end and are usu- 

 ally quite sharply sunken. In addition they are more nearly circu- 

 lar in outline than the common form described above, and the skin 

 covering the depressed areas varies in color from gray to dark brown 

 or black. Occasionally such spots have a more or less complete 

 border of blackened skin that is only slightly depressed, if at all, 

 below the level of the healthy skin. 



Bitter-pit spots on the Winter Banana are frequently large and 

 sharply sunken, and in such cases present the appearance of having 

 been formed by the coalescence of several smaller spots, sometimes 

 comprising areas half an inch to an inch long and of varying width 

 (pl.6,B,C,E). 



The presence of high concentrations of certain salts in irrigation 

 water is sometimes associated with and seems to be the cause of a 

 condition in apple fruits that can hardly be distinguished from bit- 

 ter pit. In the Pacific Northwest instances have been known where 

 such spotting developed following the use of irrigation water con- 

 taining a high percentage of Epsom salt (magnesium sulphate). 



Bitter pit can be distinguished from fruit spot by the bruiselike 

 appearance of the spots, the occurrence of the corky tissue beneath 

 them, and the absence of the speckled appearance that is charac- 



