20 the COLORADO EXPERIMENT STATION 
ground, the basin was filled again and the earth banked well about 
the trees. In hard, compact soils it is best to irrigate a few days 
prior to making the treatment so as to loosen the soil and lessen 
the labor of excavating about the trees. 
Summing up the results to September, 1907, it may be said, 
that practically all strengths of kerosene emulsion (3 per cent, to 
50 per cent.), killed the lice well when the roots had been well 
treated. Where less than 6 per cent, of oil was used, the odor 
of kerosene soon disanpeared and reinfestation soon took place by 
the lice that migrated downward from the top. Where 7, 10 or 
15 per cent, of oil was used, the effect was still more lasting, and 
tlie 20, 33 and 50 per cent, treatments gave practically perfect free¬ 
dom from lice about the crown and roots throughout the season. 
The trees in the above experiment were examined later by 
Mr. George P. Weldon, who reported upon the effects of the vari¬ 
ous applications, as follows: 
EXPERIMENTS IN THE ORCHARD OE J. CORNETTO. 
“Grand Junction, Colorado, July lo-ii, ’08. 
“I am disappointed to find [that the wooly aphis is very abundant on 
all of the roots of treated, as well as check trees, in the experiment, even 
where a 5 0 per cent, kerosene emulsion was used. Where this strength 
was applied, the odor of the soil is still very pronounced when then earth 
is stirred, and ithe trees show severe injury from the application. The 
roots are being killed and the leaves are wilting, and it is probable that 
the trees will soon die. A comparison of the treated trees with the check 
tress does not indicate that any benefit from thei various treatments has 
continued to the present time. Even where the 5 0 per cent, oil was used, 
the lice are as abundant as upon the check trees in the experiment. There 
are almost no lice above ground upon any of the trees at this time. With 
the exception of the 50 per cent, kerosene emulsion treatment, none of the 
applications seem to have done any harm to the trees. 
“Roots treated with tobacco dust, even where eight pounds to a tree 
are used, do not show any indications of benefit from the application now. 
“In the Jacquette orchard I find that the Tanglefoot bands that have 
been on for two seasons are doing serious injury to the bark of the trees, 
especially upon the south side.” 
Some orchardists have reported to us that they believe they 
have had trees sickened and even killed from the kerosene emulsion 
that accumulated about the roots at spraying time, and one or two 
have reported applying kerosene emulsion to the roots of apple 
trees during the winter for the destruction of the woolly aphis and 
that the trees all died after a few years. So, while we know that 
kerosene emulsion is a very effectual destroying agent for woolly 
aphis on roots, we are inclined to advise those who use it to be 
cautious and to keep a close watch of their trees and stop farther 
treatments as soon as any signs of injury appear. It might be well 
to select a few trees that one does not care very much for and 
