MARKET DISEASES OF FRUITS AND VEGETABLES 39 



most prevalent on apples in transit or storage, especially if tem- 

 perature and humidity are high and ventilation is poor. 



In the early stages Jonathan spots are brown, roughly circular 

 areas, y 16 to % inch in diameter, which are abruptly but only 

 very slightly sunken ; in later stages they become somewhat more 

 sunken, are irregularly lobed, and sometimes *4 inch across 

 (pi. 8, A, B). In early stages the spots are confined to the color- 

 bearing cells of the skin, but underlying tissues become affected 

 and dry out after the skin is killed. These spots sometimes be- 

 come infected with Alternaria or other rot fungi. 



The disease is important chiefly because of its effect on the 

 appearance of the fruit. Its most serious characteristic is a 

 tendency to develop in transit or storage to such an extent that 

 marked damage results to fruit that was apparently in good con- 

 dition when shipped or stored. 



Brown spots that resemble typical Jonathan spot are sometimes 

 seen on Rome Beauty apples. These seem to occur only at 

 lenticels ; they have blurred, indefinite edges, and are rarely sunk- 

 en, even as slightly as the typical spots on the Jonathan variety. 

 Nothing is known of their relation to orchard or storage con- 

 ditions except that they do not usually develop until late in the 

 storage season. In the absence of evidence to the contrary, it 

 seems best to consider them a form of Jonathan spot (pi. 8, C). 



The most effective method of controlling Jonathan spot is 

 to move apples promptly into cold storage, avoiding delays at 

 ordinary temperatures. 



(See 12, IS, US, 59, 65, 102, 105, 110, 126.) 



King David Spot 



King David spot occurs on apples of the King David variety. 

 The spots are black or dark greenish and up to about 14 inch in 

 diameter and are generally confined to the skin. Occasionally 

 they extend a very short distance into the flesh. No spots occur 

 deep in the flesh. 



King David spot is typically an orchard disease and does not 

 develop in storage. Green and blush areas on the fruit are about 

 equally affected ; sometimes the spots are confined to the calyx cup 

 or the stem basin. 



Nothing is known of how the spot is caused or how it can be 

 controlled. 



Leafhopper Specking 



After infestations by leaf hoppers (several species), apples 

 often show numerous superficial brown or black specks about the 

 size of a pinhead or slightly smaller. These are usually most 

 numerous on fruit that was exposed to dust when the leafhoppers 

 were most active. The washing of fruit to remove spray residue 

 incidentally removes leafhopper specks. 



Leaf Roller and Green Fruitworm Injury 



Large russeted and corky scars, often in scooped-out areas, but 

 sometimes in the form of small, slightly raised or undulating 

 spots, together with more or less distortion, are often found on 



