April, '10] BALL AND OTHERS: ARSENICAL I'OISONING 197 



The chemical examination of- the orchard soils and of the trees 

 for alkali and arsenic have not been completed, but the results so 

 far are almost uniform in showing very small amounts of arsenic in 

 the trees, from soils that are low in alkali, while all examinations so 

 far in which a comparatively large amount of arsenic was found in 

 the trees, have been from localities in which the alkali was so abun- 

 dant in the soil as to be in itself a menace to orcharding. 



Conclusion 



While no definite conclusions can be drawn from these preliminarj- 

 investigations as has already been suggested, it would appear that the 

 injury to the apple trees in the western country may have a number 

 of different causes. The evidence that alkaline seepage alone is suf- 

 ficient to cause the death of fruit trees seems to be conclusive. The 

 fact that the only places in which Jonathan trees are found to be 

 dying in any numbers, where other trees similarly situated are not, 

 are on areas underlaid with marl, suggests very strongly that there 

 is some relation between that condition and the death of this variety 

 of trees. The loss of a number of trees that have not been sprayed, 

 in different sections where the alkali is apparently not present in suf- 

 ficient quantities to be the killing agent, and the further fact that 

 only the Ben Davis-Gano type are killed under such circumstances, 

 indicates that we have a further factor to be considered, which we 

 are at present calling "collar rot." That free arsenic if present in 

 sufficient quantity will kill fruit trees has never been questioned, but 

 the fact that all over the country the orchards which are located on 

 suitable soils free from the other conditions mentioned, are showing 

 no injury even where heavily sprayed for long periods of time, would 

 seem to warrant the conclusion that has been previously stated by the 

 senior author, that arsenical poisoning cannot be the primary cause 

 of the death of the greater portions of our fruit trees. That where 

 alkali is present in any quantity it is probable that the arsenic of the 

 spraying solutions wall be set free and will assist in the injury to the 

 trees, .but the question whether the alkali would be strong enough in 

 this case to destroy the orchard within a few years without the other 

 factor, is a problem yet to be solved. 



