F. & F. NURSERIES 132 

SPIDER MITES. A number of different kinds infesting many plants. 
They are extremely small, greenish, reddish or brown, 4-legged crea- 
tures. They occur most abundantly on the lower surface of the leaves, 
often several hundred to a single leaf. Their injury can be determined 
by the fine speckled or mottled greenish or brownish appearance on the 
upper surface of the leaves. The small, round, pinkish eggs or white 
empty egg shells or cast skins are usually abundant and easily seen 
with a magnifying glass. 
Summer sprays containing pyrethrum or rotenone are more effective 
against spider mites than those containing nicotine. Sprays containing 
summer oils are also more effective than those containing soap or no 
wetting materials. The sprays should be diluted as directed on the 
container or usually at a strength about twice that given for plant lice. 
Be careful to wet the lower surface of all leaves and give two or three 
applications at intervals of about a week. Thorough applications with 
superfine ground sulphur dust have been found most effective. The 
over-wintering eggs of spider mites on hardy plants may be destroyed 
by delayed dormant applications of a miscible oil. 
OTHER INSECTS. There are many other insects such as beetles of 
various kinds, some caterpillars, etc., that may be killed by summer 
contact sprays. If they are hardy insects the spray should be used from 
two to three times as strong as recommended for plant lice. 
DORMANT CONTACT SPRAYS 
Dormant sprays are used for the control of the overwintering stage 
of certain insects on hardy plants. The dormant condition of the trees 
makes possible a stronger spray solution and the absence of foliage on 
deciduous plants permits a more thorough application. Dormant sprays 
usually consist of oils made miscible with water or concentrated solutions 
of lime sulfur liquid. The miscible oils are usually used at dilutions of 
1 part to 15 to 20 parts of water and the lime sulfur solution at a dilu- 
tion of 1 part to 9 parts of water. Oil sprays are usually to be pre- 
ferred but should not be used on hard maples, hickory, walnut, upright 
type of junipers, or evergreen trees where the ‘‘bloom’”’ will be destroyed. 
Lime sulfur should be used on such trees. Lime sulfur should not be 
used near buildings as it.discolors badly. 
Dormant sprays are usually used for the control of the eggs of plant 
lice, spider mites and other stages of insects that might hibernate on 
the trees or shrubs. 
INSECTS INJURING THE ROOTS OF PLANTS 
The most common forms are various plant lice, wire worms, various 
kinds of white grubs, such as the Japanese beetle grubs, weevil grubs of 
several kinds and nematodes. Plant lice may sometimes be controlled 
by mulching with 1% to %4 inch of tobacco powder or by watering the 
plants with a nicotine solution at the strength used for spraying plant 
lice. Root infesting plant lice are often attended by ants; therefore, 
control of the ants will help in getting rid of the root aphis. 
BORING INSECTS 
There are many insects that bore on the inside of the trunk, stem, 
twigs or even the foliage of plants. Usually they cannot be reached 
with either a contact spray or a stomach poison spray. When they occur 
in woody plants and make a distinct opening to the outside through 
which the borings are pushed they may be destroyed by poking with o 
flexible twig or by poking a small rag dipped in free nicotine into the hole 
or by injecting a nicotine paste material into the hole. A second type 
of wood borers tunnel in the cambium layer of the bark or in the sap 
wood. They are usually not found until considerable damage has been 
done. Stimulating plant growth by watering and the use of fertilizers 
will help to prevent their occurrence as they usually attack trees that 
have been transplanted or that have been weakened from some other 
cause. 
Borers infesting herbacious plants such as the common stalk borer, 
the iris borer, etc., often pass the winter in the egg stage on the foliage 
of dead plants. The raking up and burning of these dead plant remains 
will help very much in keeping down infestations of these borers. 
Plant Diseases of Ornamentals 
FUNGICIDES 
Satisfactory control measures for the diseases of ornamental plants 
are preventatives rather than cures. Control measures must, therefore, 
to be most effective, be initiated before the appearance of disease. 
When a plant is once infected there is often no cure, and the removal 
of such individuals and their destruction should be a general sanitary 
practice in all growing operations. 
Disinfecting and protective fungicides serve two distinct purposes. 
A disinfecting spray is used as a dormant and summer spray to destroy 
the spores of fungi which cause disease, and which may be lodged on 
the bark or about the buds of deciduous trees and shrubs. Lime-sulfur 
solution diluted 1-9 is the most commonly used dormant disinfecting 
spray. Some sprays and dusts prevent infection by depositing a protec- 
tive coating poisonous to fungous spores on the plant surfaces. Lime- 
sulfur 1-49. Bordeaux mixture, sulfur dusts and wettable sulfur sprays, 
are the most generally known and used protective sprays. 
