Bulletin 151, Truck and Garden Insects


be diluted. Black leaf 40 should be used in the proportion of 1
part to 1000 to 1800 of water. The weaker solutions such as
Black leaf 2 1/3 should be diluted with about 50 parts of water.
It is of advantage to put into the solution something to make
it stick better. A good formula is the following: Dissolve
whale-oil or other caustic soap in 5 gallons of water. If the
water to be used for spraying is soft, use 2 or 3 pounds of
soap, if hard use more. Add 2/5 of a pint of Black leaf 40 and
heat gently for 5 minutes. When ready to use dilute with
water to 50 gallons.
 In applying the spray use a nozzle of the Vermorel type
with an elbow, and be sure to spray the under sides of the
leaves, because it is there that the aphids are located. For this
reason adding tobacco extract to bordeaux for spraying directly
down upon the leaves for blight will ordinarily not give satis-
factory results in controlling aphids.
 Fumigating.-Fumigation is the most thoro method of de-
stroying the aphids on a plant. If used in time, when the
aphids are confined to an occasional hill in the field, it will be
the best method. Use a teaspoonful of carbon bisulphide per
cubic foot, under frames covered with oiled cloth.
 Dusting.-Fine tobacco dust, placed about the young plants
when they are wet with dew, will kill many aphids. When the
aphids have much of a start, this method is considerably less
effective than spraying.
 Clean Culture.-These insects spend the winter and early
spring on citrus and on many weeds. It is obvious that these
weeds should be kept down on land that is intended for melons
and cucumbers. These aphids have been observed to migrate
in the spring from citrus to melons and other curcubits. It is
therefore important that the grower should destroy the aphids
on citrus trees adjacent to his melon field before or shortly
after the melons come up. On citrus trees aphids occur only
on the new growth and especially on water sprouts. The latter
should be cut out and burned, and the valuable new growth
sprayed with tobacco solution. All infested vines should be
burned as soon as they have become valueless.