66 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
root-worm by studying the weather indications and applying the spray 
at a time when there was little probability of rain and also following 
the first spraying in about one week with an application of Bordeaux 
mixture and arsenate of lead to act as a repellent to invading beetles 
which might enter the vineyard during the dispersion period. We 
therefore suggest that the weather conditions be observed and care 
exercised to apply the molasses and arsenate of lead mixture at such 
a time when freedom from rain is to be expected for at least three or 
four days. 
President R. A. Cooley: Do you wish to ask Mr. Hartzell any 
questions or to discuss his paper? If not, we will pass to another 
paper by Mr. Lovett, “ Spreaders for Arsenate Sprays.” 
SPREADERS FOR ARSENATE SPRAYS 
By A. L. Lovett, Entomologist, Oregon Agricultural Experiment Station 
The economy of orchard spraying practices is a vital problem today 
and probably more acute in the northwest than elsewhere. This is 
due in part to our mild climate, our excessive moisture conditions in 
the spring and to the narrow margin between profit and loss, requiring 
a very high percentage of perfect fruit if our crop is to bring returns. 
This problem of economics has made necessary a very intensive 
study of spray materials at the Oregon Station, their combination, 
relative value and frequency of application and has resulted in a series 
of papers touching on this question. 
The results of the past three seasons as reported by Tartar and Wil¬ 
son (1) and Lovett and Robinson (2) on the Toxic Values of the Arse¬ 
nates has lead to the conclusion that we are using our arsenates of 
lead in more concentrated form than is necessary. Our laboratory 
experiments indicate that approximately as great efficiency is obtained 
with acid lead arsenate at a dilution of 1-400 as at 2-50. Allowing 
for the natural factors which make it impossible to achieve ideal results 
under field conditions, theoretically a strength of 1 pound of arsenate 
to 100 gallons of water should give efficient control. In spite of this 
our growers feel that sufficient additional protection is obtained with 
the July and August applications for codling moth as to warrant the 
additional expense of using 3| pounds to 50 gallons. 
A careful analysis of this condition warrants the contention that 
this apparent discrepancy is due largely to indifferent methods of 
application under average field conditions. Recent improvements in 
nozzles, combined with greater pressure, permitting the spray solution 
