PROTECTING PLANTS 195 
ately ready for use. While quickly prepared, easily applied, and gen- 
erally effective, they cost considerably more than lime-sulfur wash. 
They are, however, less corrosive to the pumps and more agreeable to 
use. They are especially valuable to the man with only a few trees or 
shrubs who would not care to go to the trouble and expense to make 
up the lime-sulfur wash. They should be diluted with not more than 
10 or 12 parts of water. Use only on dormant trees. 
Lime and sulfur wash. — Quicklime, 20 lb.; flowers of sulfur, 15 Ib. ; 
water, 50 gal. The lime and sulfur must be thoroughly boiled. An 
iron kettle is often convenient for the work. Proceed as follows: 
Place the lime in the kettle. Add hot water gradually in sufficient 
quantity to produce the most rapid slaking of the lime. When the 
lime begins to slake, add the sulfur and stir together. If convenient, 
keep the mixture covered with burlap to save the heat. After slaking 
has ceased, add more water and boil the mixture one hour. As the 
sulfur goes into solution, a rich orange-red or dark green color will 
appear. After boiling sufficiently, add water to the required amount 
and strain into the spray tank. The wash is most effective when ap- 
plied warm, but may be applied cold. If one has access to a steam 
boiler, boiling with steam is more convenient and satisfactory. Bar- 
rels may be used for holding the mixture, and the steam applied by 
running a pipe or rubber hose into the mixture. Proceed in the same 
way until the lime is slaked, when the steam may be turned on. 
Continue boiling for 45 min. to an hour, or until sulfur is dissolved. 
This strength can be applied safely only when the trees are dor- 
mant. It has been mainly an insecticide for use on San José scale, for 
which it affords a standard treatment; but recently it has been modi- 
fied for use against other insects and certain fungi (as peach leaf-curl, 
apple-scab, brown-rot). 
Four kinds of lime-sulfur preparation are now recognized: (1) the 
ordinary home-made wash for winter use (given above) ; (2) concen- 
trated commercial solutions, now on the market under various names; 
(3) home-made concentrated solution ; (4) self-boiled lime-sulfur. The 
commercial concentrates differ much in strength; and these, as well as 
the home-made concentrate, should be tested by a hydrometer before 
use, and then they should be diluted with water to a definite strength. 
The formulas for these washes are discussed on pages 539-541. 
