Page 28 



BETTER FRUIT 



February 



ABSORPTION OF ARSENIC BY APPLES FROM SPRAY 



BY PROF. P. J. 



DURING the past three years the 

 writer has been working on a 

 peculiar spotting of apples, which 

 he now strongly believes to be caused 

 by arsenate of lead. The first cases of 

 this spotting were seen in shipments 

 from Southern Oregon, and, later, upon 

 investigation, it was found that the 

 trouble was more or less general. Dur- 

 ing the past season almost every dis- 

 trict in the United States has experi- 

 enced more or less of this trouble, so 

 that it cannot be classed as belonging 

 entirely to the arid or semi-arid fruit 

 belts. Some three years ago Mr. B. 

 Waite, pathologist of the U. S. Depart- 

 ment of Agriculture, called attention to 

 the trouble, and ventured the opinion 

 that it might be caused by soluble 

 arsenic, or perhaps impurities in the 

 lead arsenate. However, Mr. Waite did 

 not make any chemical analyses in order 

 to determine the truth of his hypothesis. 

 About the same time the writer took up 

 the problem, and it has been under 

 investigation during the past three sea- 

 sons. It is not the purpose of this paper 

 to give all the experimental data, but to 

 merely state a few of the facts that have 

 been observed, and to give, if possible, 

 a reasonable remedy, so as to insure 

 against the trouble in the future. Later 

 the matter will be published in full. 



A careful examination of the spotted 

 apples shows that only the epidermal 

 and sub-epidermal cells are injured, so 

 that the injury may be said to be only 

 skin deep. The spotting may be only a 

 peculiar red mottling, with more or less 

 distinct outlines, or it may be entirely 

 black, with distinct margins. It varies, 

 however, with the different varieties, 

 and there are all gradations of injury. 

 This injury may appear before the fruit 



O'GARA, PATHOLOGIST AND ENTOMOLOGIST, MEDFORD, OREGON 



Bosc pear tree which was nearly girdled by blight. 

 When blight was cut out less than one-quarter of 

 an inch of living bark was left. Note the bridg:e 

 grafts which saved the tree. Two crops of fruit 

 have been grown since the blight was removed. 

 Tree now healthy. Read article in November issue 

 by Professor P. J. O'Gara. 



is harvested, depending upon the season, 

 but in most cases it becomes apparent 

 only after the apples have been packed 

 and have remained in storage for a 



has been indicated above, we have found 

 approximately the same gradations of 

 injury, from the red coloration to the 

 burned appearance, with this exception, 



APPLES SHOWING ARSENICAL INTURY 



short time. The spot in no way resem- 

 bles the "Baldwin Spot," which is always 

 to be found affecting the tissues beneath 

 the epidermis, and which may go to a 

 considerable depth in the flesh of the 

 fruit. The Baldwin Spot is a physio- 

 logical trouble, and is due to the abstrac- 

 tion of water from the cells. In the 

 Baldwin Spot the epidermis usually 

 remains intact, although the cells beneath 

 it may have become disorganized. It 

 has been thought by many that the pecu- 

 liar spotting in storage was due princi- 

 pally to climatic or cultural conditions, 

 or to late harvesting and over-ripeness. 

 It has also been thought that only the 

 fruits from weak trees, or trees grown 

 without any cultivation, developed this 

 trouble. However, in my experience 

 during the past three years, I have found 

 almost the reverse to be true. In one 

 particular orchard, with the trees in the 

 very best condition, and which grew 

 prize fruit, the greatest amount of injury 

 was found. On the other hand, an 

 orchard of a few trees, which had 

 received no spray treatments for the 

 past two years, and which had received 

 no other attention, did not develop a 

 single spotted fruit excepting those that 

 were purposely sprayed with a soluble 

 arsenical for experimental purposes. 



That small quantities of an arsenical 

 in solution will tend to produce a red- 

 dish color in fruits is well known. This 

 fact has been shown by experiments 

 with peaches, the results being that the 

 sprayed fruit showed a very high color 

 externally, and, besildes, the flesh was 

 even a deep red as far as the pit. It has 

 also been shown that the maturity of the 

 fruit was hastened by the spray. An 

 amount of soluble arsenic above what 

 would produce this intense color caused 

 burning of the fruit. In the apple, as 



that the injury does not extend nearly 

 so far into the sub-epidermal tissues. 



The fact that arsenic in the soluble 

 form may be absorbed by apples was 

 easily shown by careful qualitative tests. 

 These tests included not only the char- 

 acteristic March test, but other tests as 

 well. A very large number of qualitative 

 tests were made of apparently sound, 

 red-spotted and black-spotted apples 

 which were known to have been sprayed 

 with lead arsenate of certain brands. In 

 every case appreciable quantities of 

 arsenic were found. Specimens were 



Bosc pear tree showing a bad case of body blight, 

 which has been cut out. Note the bridge graft 

 which connects the healthy tissue above and below 

 the limits of infection. Read article in November 

 issue by Professor P. J. O'Gara. 



