24 
Colorado Experiment Station 
ly darker brown margin. This coloring is irregular and does not 
conform to annual rings. The trees that die of this disease, and I 
believe that they all die, linger two seasons. Further it is safe to 
predict that every tree that we now find with a corroded crown and 
some dead roots will perish within the next few years if left to itself. 
We have many trees which show no sign of the trouble above ground 
this year, but which we can safely predict will die within the next two 
years. The signs above ground are those described by Mr. Whipple. 
The trees first submitted to analysis were naturally trees that were 
very sick. But few actually dead trees have been examined. No 
such sick tree has failed to yield a strong reaction for arsenic. This 
is most abundant at the crown of the tree, less abundant in the upper 
portion of the stem and still less so in samples of the branches, but 
is prsent in all parts of the tree. 
I wish to emphasize the fact that we have two phases of the ac¬ 
tion of arsenic, first the local action of that which collects about the 
crown of the tree and that which has been taken up from the soil 
by the feeding roots and in this way passed into the tree with the 
nutrient solutions. It is evident that if the tree has been sprayed often 
enough to permit so much arsenic to collect at the base of the tree that it 
corrodes the crown and roots, the tree will also have gathered arsenic 
from the soil by means of its feeding roots and no one can say how 
much of that present in the woody tissue has been taken from the soil 
and how much has been absorbed through the wounds made by the 
arsenic on the crown and roots of the tree. 
I maintain that we have strong reasons for believing that con¬ 
siderable injury has been done by arsenic absorbed with the nutrient 
solutions when it produces what I have designated as systemic 
poisoning. This feature was merely touched upon in Bulletin 131 
because as there stated the cases of irritant poisoning are more num¬ 
erous and, I may add, more evident. 
It is evidently out of the question to give the details of sixty or 
more trees suffering from irritant arsenical poisoning. The observed 
facte are so uniform that it would only be to restate the same thing as 
many times as we should describe different trees. In every case 
we find a zone just below the surface of the ground and involving 
the large roots in which the bark of the tree is converted into a brown 
or black mass and the texture destroyed, the' woody tissue beneath this 
is in many cases also destroyed, especially of the roots; 
in the trunk it is usually partially destroyed and always more or le s 
stained of a brown color. As these trees approach death, usually 
indicated in the early fall of the year preceding this event, the fol¬ 
iage ripens early. The tree usually blooms profusely the next spring, 
sets fruit and dies early the next "fall, the leaves and fruit often re¬ 
maining on the tree in some instances until far into the winter or even 
the ensuing spring. In some cases we have a killing of the bark 
above ground. This occurs in continuous areas extending up so far 
as to sometimes involve a portion of a limb. This is shown in Plate 
2, Fig. 1, Bulletin 131. The bark is not loosened but is killed, the 
