8 The Colorado Experiment Station. 
another, soil 25.5 parts; in another 26.0 parts; in another 38.2 
and in still another, 61.3 parts per million. The sample giving 38.2 
parts arsenic acid per million was taken at the base of the tree and 
to a depth of one foot, the last sample, giving 61.3 parts arsenic acid 
per million, was taken at the base of the tree and to the depth^ of 
four inches. All of the samples were taken either in the Spring 
of the year or at least some time after the last spraying, so that 
they ought to fairly represent the orchard soils. \Ve find in fact, 
what was from the beginning patent, namely that the arsenic does 
accumulate and is already present in our orchards in dangerous 
quantities, if it, by any means, should become soluble. 
THE ARSENIC IS TAKEN UP BY THE TREES. 
It is altogether correct that the spray material applied is a com¬ 
pound of arsenic either difficulty soluble or insoluble in water as 
calcic arsenite or lead arsenate. It is also true that literally hun¬ 
dreds of trees have already died or are sick, as I believe, beyond 
hope of recovery. The symptoms are the same. The duration of 
the tree after showing the first early ripening of its foilage is about 
one year; the attack of the disease is at the same point, and pro¬ 
gresses in a uniform manner. Mr. Whipple describes its course as 
follows: 
“The first indication of the disease is the appearance on the trunk 
of spots of a chocolate color. When peeled off the bark has a peculiar 
marbled appearance, the diseased portions standing out in sharp contrast! to 
the healthy tissue.” 
“The disease soon kills the bark and it dries down to the wood, taking 
on a dark brown color. (Plate II,, Fig. 1). Two seasons are required for the 
disease to kill the trees. The first season the trunk is girdled and the foilage 
drops early. This early ripening of the foilage is often the most prominent 
symptom and diseased trees can be easily picked out in the early fall. Trees 
showing and early bronzing of foilage are generally found girdled by this 
disease. The second sieason the tree starts into leaf as the normal tree, 
gei;erally setting fruit and dies in mid-summer, ithe fruit and leaves clinging.” 
I have seen no tree in which the trouble has advanced to that 
stage indicating its death during the following summer, but that 
some of the roots, in fact, most of them in nearly every case, had 
been attacked, the bark destroyed to a greater or less extent, the 
woody tissue stained brown and the bark at the base of the trunk 
severely attacked just below the ground. It is from this point that 
the trouble seems to take its start. Some facts, however, particu¬ 
larly the condition of some of the roots, they being entirely dead, 
while others standing in just as close a connection with the diseased 
crown are in much better condition, suggest that the attack may not 
be confined to the crown. The condition of the crown produced 
by this trouble is shown in Plate II., Fig. 2, also the stained or dis¬ 
colored condition of the tissue. This is a photograph of a stump 
of a Ben Davis tree which was removed this spring, and would have 
died this summer. Plate IIP, Fig. 3 is that of another Ben Davis tree 
