8 The Colorado Experiment Station. 
1-70 was free from wilted tips, and also 2 trees sprayed with Black 
Leaf “40” 1-600. The fact that the higher strengths of Black Leaf 
did no appreciable good, would indicate that it was simply a matter 
of chance that the one tree sprayed with the weaker strength, indi¬ 
cated good results. Black Leaf “40” 1-600 apparently gave good 
results, however, because of only two trees having been treated, and 
because of the scarcity of the twig-borers in the orchard, it would 
not be wise to draw any definite conclusions without further experi¬ 
ments. The number of trees treated with lime and sulfur and their 
total freedom from borers, seemed great enough, when compared 
with the small number of check trees, and other sprayed trees with 
quite a number of borers, to justify the conclusion that “Rex” lime 
and sulfur is a perfectly effective spring remedy for this pest. For 
some unknown reason home prepared lime and sulfur used at the 
same time as the “Rex” spray, but in another orchard, apparently 
did little good. 
Mr. W. T. Clarke, in Bulletin 144, of the California Experi¬ 
ment Station, at Berkeley, gives some interesting data in regard to 
sprays applied at different times of the winter and spring, for the 
control of twig-borer. He found that during the winter season the 
little larvae, in their hibernating cells, could not be killed either with 
kerosene emulsion or lime and sulfur. He discovered, however, that 
the larvae become active in these cells for some time in the spring 
before emerging, and that during this period of activity the cells 
are rendered more or less permeable to a spray, and then the larvae 
can be successfully combated with a contact insecticide. In regard 
to the effective use of a spring spray of lime and sulfur, Mr. Clarke 
says: 
“The lime-salt-and-sulfur-sprayed trees, when the spraying 
had been done in the early spring, showed the most satisfactory re¬ 
sults of any at the time of examination. On the various station or¬ 
chards, comprising over 12,000 peach trees, the average number of 
bud-worms was about one to every ten trees, and this average was 
maintained on many orchards in the district. Indeed, it was a dif¬ 
ficult matter to find the worms in these orchards, and it was only by 
the closest scrutiny of the trees that they could be located in them. 
The general condition of these trees was excellent, and a marked 
absence of ‘curl-leaf’ was noted. 
An examination of the trees in orchard No. 1, that had been 
sprayed with the lime salt and sulful early in February, showed that 
the attack of bud-worms was severe. On many of the trees from 
which we cut the worms we found from 5 to 9 to the tree. The 
general condition of the trees was good and a very small amount of 
‘curl-leaf’ was present.” 
From this season’s experiment at Clifton, from the experience 
