368 The Principles of Fruit-growing. 
purposes, and the like, they are exceedingly useful 
and handy. The syringe and bucket pumps are 
very efficient for work upon a small scale, and 
especially when it is desired to be extra thorough. 
The greatest difficulty with the bucket pump is that 
the amount of material which can be carried is very 
small. The power sprayers (those which work from 
the wheel of the vehicle) are useful for vineyards, 
dwarf pears and low-growing plants; but, as a rule, 
they are not adapted to large orchard trees, because 
enough liquid cannot be thrown whilst the machine 
is passing a tree to thoroughly spray it. For very 
large areas and very tall trees (as street trees) steam- 
ypower sprayers must come into common use. 
7. The farmer should know what he wants to kill 
before he begins to spray.—It is common to find a 
man who is going at spraying with enthuSiasm, but 
who cannot explain a single definite object which 
he has in view. He simply knows upon general 
principles that spraying is useful. To such a man, 
spraying is spraying, whether he uses Paris green, 
or Bordeaux, or both, or neither one; and his results 
are about equal to his knowledge. There is no 
longer an excuse for such ignorance, for all the lead- 
ing insects and fungi have received more or less 
exact treatment in the publications of the experiment 
stations. The state of knowledge is far in advance 
of the state of practice. Many fruit-growers demand 
such elementary instruction as this: 
The arsenites (Paris green and London purple) 
are used to kill all larvaa or worms, and all those 
