Bulletin 123


 There are several proprietary insecticides widely sold and used
in Florida which are similar to the above in composition. These
are ready to use, except for mixing with water. The grower should,
however avoid those that contain carbolic acid, sulphuric acid, or
other chemicals that are apt to damage fruit or leaves. Others'
formula is also sold already mixed by one or more firms which
handle insecticides. Whale-oil soap, one pound to from four to six
gallons of water, is fairly good and handy for the small grower
who may not have the oils. The strength will depend upon the
weather and the water. Use it stronger in the winter and with hard
water. It is perhaps better, if one uses hard water, to first "break"
or soften it with washing soda. To soften hard water add a measured
quantity of soda (say one-half ounce) to a measured quantity (say a
gallon) of the water to be softened. A dirty-looking sediment will
appear in the water. Filter this water through a fairly closely
woven cloth, or allow it to settle, and then pour off the clear liquid
and add more soda. If no more sediment appears, you have added
enough, perhaps too much, soda; if more sediment does form, you
did not add enough soda. In the latter case, add another half
ounce per gallon and then filter and test as before. Repeat this
process until the filtered water no longer forms a sediment, and
you will have found out how much soda you must add to each
gallon of your spray solution.

 To secure satisfactory results, the application should be thorough and with
sufficient force to break up the liquid into a fine mist. The kind of pump
to be used should be governed by the size of the grove and other conditions.
A barrel pump will serve every purpose if the trees are low and only a small
amount of spraying is required. For larger operations, a gasoline-power out-
fit will give better satisfaction. For Florida such an outfit should be light in
weight, with 6-inch tires and an engine of not less than two and one-half horse-
power. To keep the machinery free from sand, the engine should be pro-
vided with canvas curtains. To obtain satisfactory results, it is necessary to
have the proper equipment for applying the insecticide. Much of the prejudice
against spraying for the control of whiteflies arises from the inefficient results
due to improper equipment.
 Since the insects congregate on the under side of the leaves, the spray
should always be directed upward. To accomplish this, one should use a
straight nozzle attached to an elbow which makes an angle of approximately 45
degrees, or, better still, an angle nozzle which will not get entangled in the
foliage and branches. A nozzle which emits the spray in the form of a cone
having an angle of about 90 degrees has been found to be very efficient, where-
as a flat or solid stream will not give satisfactory results.

 WHEN TO SPRAY.-The younger the larvae, the more easily
they are killed. Then too, by killing them in their early stages the
glower saves to the trees the sap required to bring the larvae to a
larger size, and reduces the amount of honeydew formed. On the