Arse:nicaIv Poisoning or Fruit Trkrs. 7 
portion of the trouble is the arsenic which has accumulated in the 
soil. The expression of this conviction is not a hasty one, for I am 
fully alive to how much it means to this state and all other orchard 
growing states where similar soil conditions prevail, but it is for the 
best interests of orchardists that they should know the facts per¬ 
taining to the death of their trees and the conditions of their soil. 
THR ACCUMUUATION OR ARSENIC IN THE SOIL. 
The spray material used in combating the codling moth is either 
a calcic arsenite or lead arsenate. The number of sprayings applied 
vary from two or three to nine during the season. I do not think that 
this Station has ever recommended more than three sprayings 
during the season, but many orchardists apply more. The amount 
of lead arsenate used is from four to six pounds to each 100 gallons 
of water. The average orchardist does not consider the amount of 
arsenic thus applied to a single tree a very large quantity, and he 
cannot be expected to consider the nature and possibilities of the 
material that he is applying, so in many cases he applies, as he 
thinks, wisely, a liberal quantity, sometimes using eight to ten 
pounds of lead arsenate to 100 gallons of water, and applies eight 
or ten gallons of the turbid liquid to the tree. If six pounds of 
pasty lead arsenate be used to 100 gallons of water and ten gallons 
of the mixture be applied to a tree we have six-tenths of a pound 
of the pasty arsenate, or in round numbers, three-tenths of a pound 
of dry lead arsenate. 
Practically the whole of this eventually finds its way into the 
soil. If this be repeated three times during a season we have 1.8 
pounds of pasty lead arsenate or 0.9 pounds of dry arsenate applied 
to each tree, or considering that the dry lead arsenate contains 
25 per cent of arsenic acid, we have 0.225 pound of this substance 
per tree and allowing 80 trees to the acre, we have 18 pounds of ar¬ 
senic acid to each acre of the orchard. If this amount of arsenic 
acid were evenly distributed through the first foot of soil, it would 
correspond to four and a half pounds of arsenic acid for each mil¬ 
lion pounds of soil, or 4 1-2 parts per million. This arsenic is, how¬ 
ever, not evenly, but very unevenly distributed, as the spray mixture 
runs down the trunk of the tree and accumulates in the soil at its 
base. It is not done one year only, but every year, unless there 
should be no fruit. Some of our orchards have already been sprayed 
for eight or ten years and a few of them for even a longer period, 
so that we would expect to find a considerable accumulation of ar¬ 
senic in the soil, especially in the soil at the base of the trees. This 
corresponds to the facts as found by analysis. In one sample taken 
beneath the head of a twelve-year-old apple tree, and representing 
the soil to the depth of five inches, I found arsenic corresponding 
to 30.6 parts of arsenic acid to each million parts of the soil; in 
