Arsenical Poisoning of Fruit Trees. 
13 
been shown by experiment that lead arsenate, even the tri-plumbic salt, 
yields arsenic quite freely to dilute solutions of these salts and that 
calcic arsenite (lime, sal soda and arsenic) acts in a similar manner. 
It has also been previously stated that the arsenical compounds usual¬ 
ly used for spraying are perceptibly soluble in distilled water. The 
statements made regarding this matter in Bulletin 131 are perfectly 
correct and I do not wish to change them except to lay less stress on 
the action of the alkalis, for soils entirely free from alkali contain water- 
soluble arsenic in weighable quantities. The solubility of the arsenic 
in the soil is undoubtedly favored by the presence of alkalis, but 
is not primarily caused by them. 
For some years past, since about 1904. we have been losing a num¬ 
ber of pear and apple trees by an affection which men, competent to de¬ 
termine the facts, have been unable to establish as due to any other 
cause than the corroding effects of arsenic. Among the causes con¬ 
sidered were bacteria, fungi, King disease, winter killing, alkali, etc. 
The trouble is independent of the varieties of soil, it expresses itself 
uniformly in the same manner, attacks the trees at the same point, 
runs a very uniform course in regard to both manner and duration 
and is almost uniformly fatal. Here attention should be called to the 
fact that it has been only the badly affected trees that have been observ¬ 
ed until very recently. 
In regard to the soil we have shown the extent to which 
arsenic has accumulated in the soil due to the practice of spraying. 
Further we have shown that this arsenic in the soil is soluble in 
water to an extent that exceeds the limit of safety, and that the large 
quantities of lime and iron salts in our soils do not effectively pre¬ 
vent the solution of the arsenic by pure water. We have shown 
that the alkalis in our soils may favor, but are not needed, to cause the 
solution of this arsenic. We have also shown that our virgin soils, 
a goodly number of them too contain arsenic and will show in the 
proper place that this arsenic is slightly soluble in water in six out 
of seven cases. 
The amount of arsenic present in our virgin soils, however, is 
less than one-tenth of that found in our orchard soils, and while 
it may play a part in some phases of this subject, ft does not in any 
manner enter into the question of corrosive arsenical poisoning be¬ 
cause ft is associated with the marl and for the most part lies beneath 
the feeding area of the tree and is not collected about the crown of 
the tree. 
The phase of arsenical poisoning under immediate consideration 
begins by attacking the outside of the bark at the crown of the tree 
converting it into a black, friable mass, finally eating its way through 
the bark, attacking the woody tissues and producing the death of the 
tree, either by starvation or otherwise, a question which the future 
may solve. The important fact is that the trees of which we are writ¬ 
ing, and there are many thousands of them, are either doomed to 
die within the next two years or are already dead. That portion of 
