MAKKET DISEASES OF APPLES, PEAKS, QUINCES 21 



washing solutions in which dissolved arsenic has accumulated in 

 toxic amounts. (3) By faulty rinsing facilities which permit some 

 of the solvent to remain in the calyx region, there to continue solvent 

 action on arsenical spray residue not removed in the washing treat- 

 ment. 



Arsenical injury may appear within a week or two after washing 

 but usually requires several weeks to develop on all of the apples that 

 may become affected in any lot. It seldom if ever occurs on the 

 cheek of the fruit. Chemical injuries appearing on the cheek of 

 washed apples are usually due to the solvents employed for spray 

 removal. Dissolved arsenic present in washing solutions often causes 

 such injured areas to turn black, but the primary cause of damage in 

 those areas is not arsenic. (68, 69, 70, 159,) 



INJURY BY SULPHUR DIOXIDE 



Apples are sometimes injured by accidental exposure to sulphur 

 dioxide escaping from a refrigerating apparatus in which this gas is 

 used as the refrigerant. No statement can be made as to the effect 

 of definite percentages of sulphur dioxide. It is known, however, 

 that if on\j a small quantity of the gas is present in a chamber con- 

 taining apples an injury may be produced, usually consisting of 

 decolorized, whitish, papery spots at the lenticels. If the con- 

 centration of the gas is high and remains so for several days, all of 

 the skin of fruits exposed to it becomes decolorized on yellow apples, 

 or uniformly some tint of red if the apple was originally red; the 

 flesh is softened and rubbery and usually has a strong sulphurous 

 and nauseating flavor. 



CODLING-MOTH INJURY 



(Carpocapsa pomoneUa L.) 

 OCCURRENCE, SYMPTOMS, AND EFFECTS 



Wormy fruit, injured by the larvae of the codling moth, may be 

 found on the market in apples and pears from all producing areas of 

 the United States, the proportion of injured fruit varying with the 

 locality in which the fruit is grown, and with the care under which 

 the fruit is grown and graded. 



The typical wormy apple (pi. 20, B) is too well known to require 

 an extended description. The worm may enter at the calyx, at the 

 side, or at the stem end of the fruit, and it tunnels more or less 

 directly to the core. The area surrounding the core becomes a mass 

 of dark-colored frass and fragments of fruit tissue. In leaving the 

 fruit, the larva usually goes directly from the core to the side. The 

 tunnels permit the entrance of the blue mold, AUernaria, the black-rot 

 fungus, and other rot-producing fungi. A second type of damage, 

 known as sting injury or " worm sting ", consists of small dis- 

 colored, hardened, often depressed spots, usually with a tiny hole 

 at the center (pi. 19, B). These are caused by the larvae that 

 have consumed a fatal dose of poison but have managed to burrow a 

 short distance into the fruit before death. 



