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Insects And Ailments

[Introduction]  [Planning Your Garden]  [Air, Light, And Temperature For Plants]  [Soil For Plants]  [Flowerpots]  [Potting, Watering and Feeding]  [Insects And Ailments]  [Why Some Plants Die]  [Hydroponics or Checmical Gardening]  [Kids And Gardening] 

"And against Caterpillers (whyche the Gretians name Palmer wormes) certayne dye or bestreke the plantes or trees with bloudy twiggs.

Against Snayles both wyth Shel and without Shel . . . soote of chimneis sprinkled and strewed abrode, the like helpeth." THOMAS HYLL " First Garden Book."

Your indoor plants are subject to the same troubles as those in an outdoor garden. Take precautions against disease. Do not wait until molds, spots, warts, mildews or other blemishes tell you that fungus is present; for when you see fungus injury, the parasite causing it is already established within your plant. You cannot cure it by spraying; the most you can do is to cut away the infected branches and leaves and to spray with a fungicide in the hope that you will slow its further development and prevent its spread to other plants.

You will need a protective tent within which plants may be sprayed or dusted without injuring the room. Construct a threesided screen to be set around a group of plants. It may be made of stout cardboard, with hinges made from adhesive surgical tape; or it may consist of three frames of light wood-I/2-inch by 2-inch lattice is suitable-and small brass screw-eyes combined with large headed nails will serve as hinges. Tack on the frames some shower-curtain material. Or you can cement to them aluminum foil to double as a reflector

The most widely used fungicide is Bordeaux mixture or "Bordo," a compound of copper sulphate and lime. Follow exactly the directions on the container, because the use of materials strong enough to kill fungi yet weak enough to cause no injury to your plants is a delicate matter. Use a fungicide too strong or too often and you may injure or perhaps kill the plant you are aiming to protect. Recent developments in fungicides include Fermate, which is safer and equally effective; others are Cuprocide, Perzate, Rose-dust and Zerlate, which you may wish to substitute for Bordo. Unless the fungus attack is serious, or you fear one may come, do not spray while plants are in flower. If you must spray flowering plants, first shear off all buds and flowers.

Fungus spores are in all soil. Before planting, you may kill many of them by treating soil with Dowfume-again, follow directions implicitly. Some gardeners pour boiling water on a pailful of potting soil and let it stand until cold; they pour off the water and, spreading the soil on oilcloth in the open air, allow it to take several days to dry; then they break it up and use it. Do not sterilize soil by placing it on a pan over dry heat, for you will probably destroy the humic ingredients, making it useless.


In eliminating insects we have a problem akin to that attendant on fungi: we must use material that is strong enough to kill the insect and its eggs without injuring the plant. Once more, it is important that we follow the directions on the container. The number of remedies is legion; many are of great value to the professional gardener, but there is at the end of this chapter a list of those helpful to the room gardener with his limited facilities.

Again, unless the attack is serious, don't spray when the plant is in flower. Put on rubber gloves and see if you can hand-pick the insects or brush them off with a piece of cotton batting moistened with insecticide properly diluted.

The Sap-sucking Insects. Keep a sharp eye open for them and for the damage they do. Look for yellow, crinkled or blistered leaves; on the back of a leaf you may find crowds of insects. Numbers may be seen suddenly on the growing tips of almost any plant. Look for slow-moving creatures which you may identify as aphis or plant lice. Mostly they are green or black, but they may be almost any color. They live by extracting the juices from the young growth. Black-Leaf 40, diluted with soapy water, is the usual remedy.

Another group of sucking insects are the scales. Similar in harmful effect to the aphids, they protect themselves from their enemies and from our sprays by developing a tough shell under which they feed. Almost every plant has its own particular scale, the shell looking like a tiny limpet, oyster, barnacle or shield. Penetrating materials which work their way under the shell have to be used, and a reliable one is Volck.

Thrips is a sucking insect almost invisible to the naked eye. Amaryllis, calla, chrysanthemum, gladiolus, freesia, iris, narcissi and many other house plants may at some time or another be attacked by it. It causes shoots to become yellow, buds to become blasted. Leafhoppers are active jumping insects, about 1/5 inch long; they also suck the plant juices and cause the leaves to turn yellow or white. Spraying with Black-Leaf 40 mixed with strong soapsuds is usually effective against the thrips and leafhopper.

Whiteflies comprise another group of sucking insects. When a branch is jarred they will fly up in clouds from the under side of the leaves. Black-Leaf 40 with soapsuds is the remedy.

Mealybugs are sucking insects whose bodies are covered with powdery white wax. Volck may be used.

Lacebugs suck plant juices from the under side of the leaves of a few plants. Treat with Black-Leaf 4o and soap.

Red Spiders, Mites and Midges. Red spiders and other mites are so small as to be almost invisible; they will suck the juices from any plant, causing premature drying of the leaves. Gardeners find they are encouraged by an overdry atmosphere and too high a temperature. Dimite may be used to control them.

Midges are very minute flies; in this family are the kinds that get into our hair and eyes when we venture into the spring woods. Some attack house plants, notably the chrysanthemum gall midge, whose small maggots bore into the leaves and stems to cause hundreds of small swellings or conical galls, in which galls are maggots, turning later into pupae and finally into flies or midges. Try Black-Leaf 40.

Nematodes. Also known as eelworms, these also are microscopic creatures that live in the soil moisture, entering the roots of many plants to cause galls or knots. The one attacking chrysanthemums causes an easily recognized injury-a tan V-shaped discoloration of the leaf, which dries up; this occurs progressively up the stem. Similar injury occurs on ferns, begonias, anemones, African violets, zinnias and calceolarias. When the leaves are not damaged by fungus, for there is no mold or spot, and the injury is confined to the areas between the larger veins, it may be ascribed to nematodes. Some nematodes cause roots to become enlarged with rounded galls. Still another causes the ring disease in narcissus and daffodil bulbs; if a bulb be cut crosswise, affected leaf bases, which are circular when the bulb is cut in this direction, are dark brown. Apply Dowfume or sodium selenate to the earth. Use freshly mixed potting soil, not old salvaged soil.

Chewing Insects, Beetles and Caterpillars. If leaves are perforated with many small holes, uniform in size and appearing to have been hit by a gun blast delivering small bird shot, the trouble is probably due to flea beetles. Use a rotenone preparation.

Cutworms live in the soil and eat young plants, usually biting them off completely at the surface of the soil. Place some BugGeta or Snarol on the soil at the base of the plants.

If leaves are eaten along the edges and perforated between the veins, the probability is that some of the beetles, caterpillars, spanworms, loopers or inchworms are taking their toll. Look for the troublemakers and pick them off if you see them; then spray or dust your plants with DX Pyrethrum-rotenone, Protexall or another rotenone preparation.


An abridged list of the materials you may use.

Ant Traps.  A few placed around will take care of most colonies.

Aramite.    For red spiders and mites.

Black-Leaf 40, diluted with soapy water. For sucking insects. Bordeaux mixture or Bordo. A fungicide.

Bug-Geta pellets. Poisoned bait for cutworms, snails and slugs. Chlordane, 6 per cent dust. For ants.

Cuprocide. For fungus diseases.

D.D.T., 5 per cent dust. Effective against Dimite. For red spiders and other mites.

most insects.

Dowfume. Mixed with the soil, it controls soil pests and some fungi; it also kills many weed seeds.

Dupont Floral Dust. A combination control for fungus and insects.

DX Pyrethrum-rotenone Spray. For sucking and chewing insects.

Fermate, Fungine, Parzate. Three reliable fungicides. Lemon Oil.  For plant lice, leafhoppers and some scales. Protexall Spray and Dust. Combination fungicide and insecticide.

Rotenone preparations: Red Arrow, Rotecide, Rotenone Garden Guard. Effective against some insects, especially the Japanese beetle.

Sodium selenate. Mixed with soil in which plants are growing, it enters the plants which become poisonous to thrips, midges and leaf nematodes. Never use it on food plants.

Soilfume Ethylene Dibromide. Capsules placed in the soil fumigate against wireworms and nematodes.

Triogen Spray and Triogen Dust. Fungicides and insecticides. Volck. An oil-spray insecticide.

Zerlate. A fungicide.

SICKNESS DUE TO BACTERIA AND VIRUSES Little can be done against these two types of trouble. They are akin to troubles among people, though they do not seem to be communicated from plants to man. Fortunately they are rare.

Bacterial diseases usually cause a blasted plant, the growth of cankers and galls, and a remarkable multiplication of roots, leaves and stems.

Virus diseases often cause plants to be paler than they should be, dwarfer, with more branches than normal, prematurely mature: the leaves may drop off before they should. The leaves of many infected plants become mottled like a tabby cat.

When either of these conditions is suspected, the plant should be burned, the soil thrown away, and the pots washed thoroughly with a detergent and then boiled.

Aphids and other insects are accused of carrying bacteria and viruses to healthy plants, so every effort should be made to keep all insects under control by spraying and dusting.