COMBINED SPRAYS FOR CONTROLLING INSECT PESTS. 
. It can safely be said that in all these requirements Australia is many 
years behind the times. There are various power-spraying plants in 
operation, but they are not comparable to either the best English or 
-American equipment. Some of the large machines have tanks to hold 
200 gallons of wash, and their pumps are capable of delivering up to 
2,000 gallons per hour at pressures from 200 to 300 lbs. per square inch. 
In orchard work these high-power pumps are sometimes connected to a 
permanent system of iron piping laid so as to supply large areas from 
u common centre which is near the water supply for mixing the wash. 
The prepared solution is pumped through the permanent mains, and is 
delivered by a number of nozzles (e.g., 10 to 16) at one time. This is 
a most efficient and economical method. The highest and leafiest of 
trees are now readily sprayed, e.g., the large elm trees in the Capitol 
grounds at Washington, and various university grounds, to poison the 
elm leaf beetle (@alerucella luteola). A few years ago, had there been 
any high-power apparatus available, the rows of pines round the Manly 
Beach, Sydney, ¢ould readily have been sprayed to control the Golden 
Mealy Bug (Pseudococcus aurilanatus), which so disfigured the trees 
that the council had them eradicated. 7 
On the question of nozzles there is also a lamentable ignorance. 
Many growers know little more than an adjustable Bordeaux nozzle, 
which is used for all purposes. Although different. nozzles are suited 
to different work, their efficiency depends on their structure and the 
pressure used in spraying. According to their construction they may 
be divided into three simple classes after the type of Bordeaux, Vermorel 
and Disc. The Bordeaux is adjustable by means of a stop-cock, and 
yields mostly a fan-shaped spray. ‘ Seneca” is a form developed for 
lime-sulphur spraying. The Vermorel type gives a’ fine cone-shaped 
spray, but is very liable to clog, and is not very suitable for large out- 
fits for large orchards. . Vermorel, Cyclone, Eureka, Dewey, Vapour 
Mist are trade names of this type. The most efficient type of nozzle 
at the present time is the Disc, which has been evolved from the Vermorel. 
Jt is larger than the Vermorel, and at the orifice has a disc plate which 
can be changed when desired to control the size of the outlet. It has 
a broad, flat chamber into which the liquid is forced through two spiral 
grooves, having first passed through a strainer. A strong rotary motion 
is given to the liquid, which breaks up into a fine spray as it leaves the 
large central orifice or outlet. Trade names are Friend, Atomic, 
Mystery, Jumbo, Power, Simplex, Tiger, Whirlpool, Spraymotor, Masso- 
spray, Scientific, Excellal, and Champion-Variable. There are various 
modifications of the dise type, and these variations greatly influence 
the efficiency of the nozzle, which normally gives a hollow cone of spray ; 
that is, it deposits a ring of particles on a given surface. The ring is 
reduced or the angle of discharge is narrowed with increase of pressure, 
and at the same time the fineness of the deposit is increased. Some 
nozzles have a basal plate forming the floor of the eddy chamber with a 
ventral hole drilled through it, and the orifice of this hole may be 
cither flush with the surface of the plate or be raised on a ‘conical boss, 
termed the post. The post, with or without a central hole, is placed 
below, and directly in line with, the outlet orifice. The central hole | 
converts the hollow cone of spray ‘into a solid cone, diminishes the angle 
of discharge, and increases the size of the spray particles. The post 
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