131 SPRINGFIELD, N. Jf. 

CONTACT SPRAYS 
Contact sprays are of two kinds. Those used on plants during the 
growing season and known as summer contact sprays, and those used 
on hardy plants while they are in resting or dormant stage, are known 
as dormant sprays. 
Summer contact sprays are of many kinds. The most common ones 
contain either nicotine, extracts of pyrethrum flowers (pyrethrins) or 
extracts of derris or cube roots (principally rotenone) as the principal 
killing agent in water, alcohols or oils. Soaps and the so-called white 
oils are also effective against some insects, such as plant lice, crawling 
stages of scale insects or other young insects. There are so many dif- 
ferent kinds of contact sprays and they vary so much in their composi- 
tion and formulae that general directions are difficult to give. State 
and Federal laws require that they be true to label and directions; 
therefore they should be used as directed on the containers. 
Contact sprays kill by wetting the surface of the insect to be killed. 
Therefore, the spraying should be thoroughly applied to all parts of the 
plant, both upper and lower leaf surfaces. Many contact sprays contain 
either soap, oils or other materials to make the diluted spray wet better. 
If they do not contain a wetting agent or if the dilution with water is 
rather high they can often be made more effective by adding soap. 
Powdered or dry soaps should be used 1 part to about 200 parts of the 
diluted spray. Liquid soap should be used diluted from 2 to 4 times 
as much as the actual amount of soap they contain. Thus, a liquid soap 
containing 15% actual soap should be added 1 part to 30 to 60 
parts of the diluted insecticide spray or liquid soap containing 40% 
actual soap should be added 1 part to 80 to 160 parts of the diluted 
insecticide. The concentration of soap will depend upon how hard the 
insects are to kill and whether the plants are tender or hardy. 
The insects controlled with summer contact sprays may be divided 
into several groups according to their habits and difficulty of control. 
These groups are as follows: 
PLANT LICE (also called aphids and green fly), infest many different 
kinds of plants. Soft bodied, whitish, green, brown or sometimes almost 
black in color, usually not more than 'g inch long. Generally found 
clustered on the under surface of leaves, or along the new growth of 
stems. To control, dip or spray plants in any of the summer contact 
sprays diluted with water as recommended on the container. Be care- 
ful to wet the lower surface of the leaves. It is often advisable to give 
a second treatment in 5 or 6 days. 
PLANT BUGS, such as leaf hoppers, tarnished plant bugs, ‘white 
fly,’ thrips, etc. All are sucking insects and they are more active than 
plant lice, therefore, much more difficult to wet all the insects with the 
spray material. Use summer contact sprays as recommended on the 
container or at strength slightly stronger than recommended for plant 
lice. Use considerable volume of spray where possible and wet lower 
surface of leaves. It is often necessary to give 3 or 4 treatments at 
weekly intervals. Nicotine or pyrethrum dusts are very good where 
plants are crowded or close together. 
MEALY BUGS. These are sucking insects covered with a white, pow- 
dery or woolly, wax-like material. The eggs are pinkish, small, laid in 
masses of 100 or more and covered with the white, woolly, wax-like 
material. Both the insects and egg masses are difficult to wet with the 
spray material. Sprays containing nicotine are usually better for mealy bugs 
than those containing pyrethrum or rotenone. Sprays containing summer 
oil or wetting agents with oil are more effective than soap or other 
common wetting materials. Spray with considerable force and where 
possible repeat the applications at 3 or 4 day intervals until the in- 
festation is cleaned up. Large masses of mealy bugs or egg masses that 
are hard to wet may be painted with a solution of the spray material 
4 to 6 times as strong as recommended for control of plant lice. After 
a few minutes or when these painted places have been wet through 
syringe with clean water and spray with the regular strength recom- 
mended for mealy bugs. 
SCALE INSECTS. Two types are commonly found on ornamental 
plants. One type is called armored scales because the body is covered 
with a round or oval, flat, wax-like scale, usually not more than ¥ 
inch in diameter. The second type is called soft scales, because they 
have no protecting waxy scale, or they are sometimes called lecanium 
scales because of their shape. They are usually oval in outline, flat to 
hemispherical: in shape and from 1% to 34 inch in greatest diameter. 
Both types are difficult to control with summer sprays after they become 
half grown or more. Regular spraying at about 10-day intervals with 
a summer contact spray about twice as strong as recommended for 
control of plant lice will kill the young insects and clean up an infesta- 
tion. Contact sprays containing summer oils are more effective against 
scale insects than those containing soap as the wetting agent. On hardy 
ornamental plants scale insects are best controlled by a delayed dor- 
mant application of miscible oil or concentrated lime sulfur solution. 
