6 The Colorado Experiment Station. 
Whipple’s very brief account of this disease is that the disease had 
been noticed for only two or three years. Information which he 
and I have since gathered corroborates this statement; the earliest 
observation of the affection of the trees of which we were able to 
learn was in 1904 and trees have been dying in certain orchards 
annually since that date. 
varieties AEEECTED. 
The varieties affected in this way are by no means confined to 
the Ben Davis and Gano. The following varieties are also affected: 
Spitzenberg, Early Harvest, Wolf River, Lawver, Blacktwig, Bald¬ 
win, Jonathan, Grimes Golden, and Pewaukee, and without doubt, 
other varieties might be added if search were made to find every 
variety affected in this way. The trouble also extends to pear trees, 
but I have studied apple trees mostly. 
AREA INVOLVED. 
At this writing I am not prepared to give any territorial limits 
to the trouble. I have observed it from near Fruita almost to 
Palisade and in the neighborhood of Delta. I am further credibly 
informed that the same condition of the trees has been met with in 
the neighborhood of Canon City. If this latter statement is correct, 
our principal orchard growing sections are involved and the im¬ 
portance of definitely establishing the cause and if possible, a cor¬ 
rection for the trouble, becomes very great. 
THE NUMBER OE TREES AEEECTED. 
This would be very difficult to determine and I have no data 
on which to base even a rough estimate, but an idea may be obtained 
from the following facts. . One man stated that in the last few 
years, he had lost 50 per cent of his Ben Davis. Another stated 
that he began pulling up a few trees four years ago and this year 
he had removed nine trees and there were others which he should 
have removed; another man had removed twelve and still another 
the same number. The four Ben Davis trees in the row that I 
saw last October, together with others had been removed this 
Spring and there were still other trees in this orchard which were 
affected. I visited one orchard in which there was a large number 
of affected trees—in other orchards, there are only a few. The 
total number of affected trees in the orchards of the Western 
Slope, is already unfortunately large. 
THE probable cause OE THE TROUBLE. 
I have already clearly indicated my conviction that the cause 
of the trouble is arsenical poisoning; that there are some trees suf¬ 
fering from other causes is quite certain but the cause of the greater 
