THE COLORADO EXPERIMENT STATION 
16 
ment referred to is a common formula where both quick lime and 
caustic soda produce the heat of the mixture.* Another formula 
sometimes used by growers provides for an excess of quick lime to 
produce the boiling heat. Others use this method except that hot water 
is required to quicken the slaking process. The formula using caustic 
soda, probably the best of the above self-boiled mixtures, though 
saving cost of boiling by fire, increases the cost of the mixture. At 
average local prices at the point where the experiment was conducted, 
the cost of the mixture was $3.45 per 200 gallons as compared with $2 
per 200 gallons for the standard orchard-boiled wash. 
It has seemed to the writer that attempts at preparing the mix¬ 
tures without the aid of external heat has usually resulted in leaving 
a portion of the sulfur uncombined. This is indicated by the yellow 
color of the mixtures so prepared. A wide difference in the color 
of the sediment was noted in the mixtures prepared by different 
methods in the experiment. The ratio of sediment to liquid also 
showed wide differences. The strength of the lime-sulfur wash will 
depend upon the strength of the soluble portions and upon the sedi¬ 
ment. The sediment is supposed to gradually decompose into nascent 
sulfur, which remains upon the tree and continues destructive to insect 
life for a considerable time. An excess of coarse sediment in the 
spray is a disadvantage in that it clogs the nozzles and increases the 
wear on the pump. 
Lime-sulfur washes were originally boiled by fire two hours or 
more. Later observations show that less time is sufficient. About 
forty-five m’nutes will generally form as effective a spray as can be 
secured, though the proper time required for boiling must be indicated 
by the changing of the undiluted mixture in the boiling vessel from 
a yeflowish to a dark amber color. A properly boiled mixture, after 
diluting for spraying, will be of a reddish orange color and have a 
greenish sediment. The lime and sulfur should be boiled in about 
one-fifth the total amount of water and then diluted with either hot or 
cHd wMtt to make desired quantity of spray. Undiluted mater'al 
should not be allowed to remain over night in the boiling vessel, for 
it will harden. Standard lime-sulfur mixture is intended for imme¬ 
diate use. So caustic is the spray that the hands of one using it should 
be protected by gloves. Apparatus should be rinsed with water each 
time after using. 
Directions tor Preparing Standard Lime-Sulfur Wash. 
The following formula and brief description for preparation of a 
small amount of the standard lime-sulfur wash is recommended for 
Howard scale. 
Formula. 
Quick or lump lime .15 pounds 
Flour or flowers of sulfur.15 pounds 
Water.50 gallons 
To prepare fifty gallons of spray place seven to ten gallons of 
*N. Y. Agr. Exp. Sta. Geneva, Bulletin No. 247. 
