90 FUNDAMENTALS OF FRUIT PRODUCTION 



ing, described by Brooks in the preceding paragraph, but without external pits 

 and with the surface of the apple thrown into a series of elevations and depres- 

 sions. A large number of brown corky areas occur throughout the flesh, follow- 

 ing closely the course of the vascular bundles. In no case do these extend 

 outward as far as the skin, consequently there are no external brown pits charac- 

 teristic of true fruit-pit or stippen. A further difference from the usual type 

 of fruit-pit is that the spots are not more abundant in the peripheral zone, but 

 are scattered throughout the flesh of the fruit. There is no bitter taste connected 

 with this disease in Fameuse apples. ^^ 



"Under the microscope the internal brown spots of cork appear as aggrega- 

 tions of cells with brown shrunken contents. A number of the cells, though not 

 all, are shrunken and collapsed. Around the corky portion the healthy cortex 

 cells form a ladder-like arrangement of smaller, more nearly rectangular cells. 

 It is as though they had been stimulated to rapid division in response to the 

 decreased pressure from the direction of the diseased area. Outside of this zone 

 the pulp cells are normal in size and form. The close relation of the dead spots 

 to the vascular system is very evident under the microscope. "^^ 



Surface Drought Spot. — "An early stage of the disease is manifested by an 

 irregular light-brown area in the skin. When the fruits affected are large, two 

 or three centimeters in transverse diameter, the surface of the fruit is usually 

 smooth and regular, there is no shrinkage or sinking in, nor anj^ abnormality 

 in the flesh beneath. . . . When the spot first appears tiny drops of a clear or 

 yellowish gummy exudate may occur on its surface. Under the microscope this 

 exudate shows as a clear gum. ... It is considered to be merely an expression 

 of cell sap from the diseased hypodermal cells. . . . Most of the fruits 

 affected when young drop from the tree. Some of them . . . persist, and as 

 they grow the affected areas become roughened and cracked."'^ 



Deep-seated Drought Spot. — "This type of lesion is characterized by the 

 presence of brown, corky areas in the flesh of the apple and by a sinking in of 

 portions of the epidermis. On young fruits, from 1 to 2 or 2J'^ centimeters in 

 transverse diameter, the disease appears as a large brownish area in the skin of the 

 fruit, usually near the blossom end, which is irregularly sunken and wrinkled, 

 indicating shrinkage of the tissues beneath. Cross-sections show brown areas 

 in the flesh near the periphery. These are opposite the main vascidars, and often 

 in the center of one of them there is a large cavity, the apex of which reaches one of 

 these vessels. (Occasionally, apples are found in which there is one of these 

 corky areas or cavities opposite each of the 10 main vasculars.) These internal 

 spots are often connected by a narrow brown streak running close to the periphery 

 of the apple. Sometimes these streaks do not connect, but extend only a short 

 distance in either direction from the central spot. The shrinkage of the skin 

 over a considerable area, and the presence of these brown corky spots and streaks 

 in the periphery, suggest the type of fruit-pit described by McAlpine as 'con- 

 fluent bitter-pit' or 'crinkle.' . . . Microscopically, sections of the diseased 

 spots show that the trouble is confined to two or three layers of the hypodermal 

 parenchyma, usually the inner layers, though sometimes the entire hypodermis is 

 affected and a few dead cells are also found in the flesh. The diseased 

 cells retain their normal outline, but their contents have become brown and 

 amorphous. "^^ 



