REMOVAL OF SPRAY RESIDUE FROM APPLES AND PEAES 13 



injury to the fruit. This statement presupposes the proper operation 

 of suitable equipment and assumes that certain precautions have been 

 taken in order to avoid the injuries which may be induced by 

 cleaning treatments and the consequent decay of the fruit. 



These injuries, which are considered in greater detail in the fol- 

 lowing paragraphs, may be classified as follows: Arsenical injury 

 at the" calyx or stem, hydrochloric-acid burning, and chemical injury 

 at the core. 



ARSENICAL INJURY 



Arsenical injury is usually localized in the calyx region. It 

 appears as a depressed black or dark-brown area surrounding the 

 calyx or occasionally as dark patches of dead skin on the sides 

 of the calyx cavity. In some cases or in advanced stages the injured 

 area may extend one-eighth of an inch or more into the flesh, the 

 affected tissue becoming brown and dry. Sometimes the same injury 

 is found at the base of the stem. This injury opens the way for 

 storage rots, especially when the fruit is stored wet. 



This form of injury was prevalent on Jonathan apples washed in 

 certain types of equipment, and its association with washing treat- 

 ments employing hydrochloric acid led to a popular assumption that 

 it was hydrochloric-acid burning, but it was equally prevalent on 

 apples cleaned by alkaline solvents. 



The same injury has also been of rather frequent occurrence on 

 heavily sprayed apples in the orchards during rainy fall weather, 

 and in former years it has been observed in storage on uncleaned 

 apples that were packed wet. It was also produced experimental!}' 

 by thoroughly wetting uncleaned apples after they had been picked 

 and then packing and holding them in tight containers that would 

 not permit the evaporation of the water. 



Further evidence that the cause of the injury is soluble arsenic 

 and not hydrochloric acid has been found in chemical analyses of 

 injured flesh tissue taken after carefully peeling the affected area. 

 Soluble arsenic has been found in all cases., whereas no traces of it 

 could be found in adjacent normal tissue. 



The occurrence of arsenical injury of this type on uncleaned apples 

 may be explained by the accumulation of soluble arsenic from the 

 sprays applied. This process is inaugurated when moisture is pres- 

 ent and may be facilitated by the presence on the apples of small 

 quantities of alkaline soil dust. 



It has also been found that the same type of arsenical injury oc- 

 curs when spray residue is incompletely removed from the calyx 

 region. In such cases it appears that the disintegration of the lead 

 arsenate begins in the washing process and continues under the in- 

 fluence of solvents or moisture retained on the apples when they 

 are packed, and thus soluble arsenic is produced. 



The prevalence of arsenical injury at the calyx was influenced by 

 the manner in which the washing solution was employed, its strength, 

 and the duration of exposure of apples to the solution. The injury 

 was greatest where apples were clipped in boxes or submerged by 

 other means. The stronger the cleaning solution the greater the 

 injury developed. Prolongation of the time of exposure of the fruit 

 to the cleaning solution increased the extent of damage. Washing 



