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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
SPRAYING EQUIPMENT FOR CITRUS TREES IN CALIFORNIA 
By Frank B. Herbert, Assistant Entomologist , Balfour Guthrie & Co. 
Abstract 
There are two citrus districts in California,—Tulare County with medium sized 
open trees, where good results can be obtained with usual four horsepower spray 
machine,—and Southern California, with larger, denser trees, where the largest 
orchard sprayers (10 horsepower), are required. These machines have a capacity 
of 15 to 20 gallons per minute and carry 350 and more pounds pressure. Spray 
guns are used almost exclusively, with disc apertures ranging from ^ to ^ inches. 
In Tulare County the average tree requires 8 to 10 gallons of solution, making a 
cost of 4 to 15 cents per tree for the application, and in Southern California, requiring 
12 to 15 gallons, making the cost of applying run from 6 to 19 cents per tree. 
From time to time growers and county officers have requested data 
on spraying equipment for citrus trees, with special reference to the 
pressure desirable, size of gun discs, number of gallons required per tree, 
cost of application, etc. Therefore the writer has endeavored to record 
some of the requirements in this paper, the data being taken from the 
records of sprayers and from general experience, and not from any 
special experiments performed. 
Citrus Districts 
There are two distinct citrus districts in California. Southern 
California, where spraying on a large scale for any pests except red 
spiders, is quite new, and Tulare County, where spraying has been the 
principal means of pest control for a number of years. Full grown citrus 
trees in the former district become very large and require special equip¬ 
ment in order to properly cover them, while those in Tulare County 
average much smaller and can be more easily covered with the ordinary 
sized spray machine. 
Type of Machine 
A great deal of the spraying in Tulare County is done by the individual 
grower who owns his own spray rig and does his work when he pleases. 
Most of these machines are of the larger sizes having single cylinder 
engines throwing from 8 to 12 gallons per minute. The “Bean” has 
been the favorite in this territory until now the “Friend” is ccming to 
the front. As most of the trees are not over 15 feet high and are fairly 
open, the grower has been able to get by very well with this sized outfit. 
In quite a few cases the grower uses only one gun with this machine. 
South of the Tehachapi, the commercial sprayer has been doing the 
bulk of the spraying, partly because it is a new business and partly 
because the trees have been so large that they required a large machine 
which the ordinary grower has not felt he could afford. Some of the 
smaller machines, which were used for spider spraying, are still in use, 
