Healthy, disease and pest-free plants will help to make your garden the envy of the neighborhood.
Grow flowers adapted to your area. Plant them in well-prepared, well-drained, fertile soil.
Do everything you can to keep the plants watered in drought, mulched in hot weather, and protected in winter.
Collect and burn plant debris in the fall. Keep the garden area free of weeds (they often harbor pests).
Add to these good practices the habit of following a regular preventive spray or dust program, applied at five- to seven-day intervals.
Multi-Purpose Spray And Dust Mixtures
Multi-purpose spray and dust mixtures are generally more convenient to use in the garden than those which deal with only one group of pests.
Choose a pesticide containing several of the following ingredients:
- Malathion (to control most insects and mites)
- Kelthane
- DDT
- Methoxychlor or sevin (to control leafhoppers and leaf-feeding beetles)
- Captan
- Phaltan
- Zineb
- Maneb or thiram (to control fungus diseases)
Mites
Mites are small, active creatures resembling specks on leaf undersides. Infested leaves look yellow and webby. Heavy infestations develop quickly in dry weather.
Control: Spray or dust with malathion or kelthane. Repeated applications may be necessary. (DDT and sevin kill many insect predators that feed on mites.)
Aphids
Aphids are green, brown, pink, or black, soft-bodied, slow-moving insects 1/16 to 1/8 inch long. They are sometimes called plant lice.
Found in colonies on succulent shoots, stems, or leaves, they suck plant juices. Infested plants are stunted, and leaves curled. Plants are generally unsightly.
Control: Spray or dust with malathion at five- to seven-day intervals.
Mealy Bugs
Mealybugs are white, soft-bodied, slow-moving insects flattened in appearance. Bugs appear to be covered with a white or grayish-white powder. They suck plant juices, causing leaf curling and stunting.
Control: Spray or dust with malathion.
Leafhoppers
Leafhoppers are green, yellow, brown or multicolored, wedge-shaped insects about 1/8 inch long Adults readily fly when disturbed. Young or nymphs cannot fly but move quickly about on the underside of leaves. Infested leaves curl and turn brown. Damage is called “hopper burn.”
Control: Spray or dust with malathion, DDT, methoxychlor, or sevin.
About Plant Bus And Scales
Plant bugs are active sucking insects of various types, about ¼” to ⅜” inch long. No colors predominate, but generally tan, black, or green in appearance.
Young nymphs are green, some with black spots, and very active. Suck plant juices and damage blossoms. Heavily-infested plants may not bloom.
Control: Spray or dust with malathion, DDT, or methoxychlor.
Scales are small elevations that look like clam shells or pimples on twigs, stems, and foliage. Newly hatched scale nymphs are very active but soon settle in a favorable location and secrete a hard shell-like covering; suck plant juices and weaken or kill infested areas.
Control: Spray or dust with malathion.
Leaf-feeding Insects, Thrips, Soil Insects, And Borers
Leaf-feeding insects are chewing kinds that feed on foliage and blossoms. Mainly beetles and caterpillars of various types. Some, like leaf miners, feed between the upper and lower surface of the leaf.
Control: Spray or dust with malathion, DDT, or sevin.
Thrips are minute yellow, brown, or black insects 1/16 inch long and very slender. Abundant in blossoms and on leaf undersides. Thrips puncture surface cells and suck up exuding sap.
Infested foliage becomes blasted and silvery looking. Blooms deformed; buds may not open. Frequent pest of glads and gloxinias.
Control: spray or dust with malathion or DDT.
Soil Insects
Soil insects include root aphids, ants, grubs, wireworms, maggots, cutworms, and webworms that live in the soil and feed on the underground parts of the plant.
Control: Before planting, make application of granular chlordane, aldrin, dieldrin, or heptachlor. Mix with the soil in the flower bed or the furrow with individual bulbs or transplants.
Borers
Borers are small to large, light-colored larvae or worms that feed inside stalks, rhizomes, or stems. They weaken plants; infested portions may break over or die.
Control: Sanitation; spray or dust with DDT.
Leaf Spots, Gray-Mold, and Powdery Mildews
Leaf spots and blights vary in size, shape, and color on the leaves, sometimes on stems and flowers. Spots may enlarge or run together, forming blotches or a blight. Mold growth may be evident in diseased areas.
Infected leaves commonly wither, die, and fall prematurely. In addition, certain spots and blights may have special names—blackspot, downy mildew, anthracnose, or spot anthracnose.
Control: Sanitation; rotation; spray or dust with captan, zineb, phaltan, maneb, or thiram.
Gray Mold
Gray-mold or botrytis blight and blossom blights cause soft, tan- to brown-colored spots and blotches on leaves, stems, and flowers. Affected parts may be covered with mold growth in damp weather; rot quickly.
Control: Sanitation; avoid overcrowding; spray with captan, zineb, thiram, maneb, or phaltan.
Powdery Mildews
Powdery mildews are white to light gray, flour-like coating sprinkled on leaves, buds, young shoots, and even flowers. Leaves may turn yellow, wither and die prematurely. Generally common from mid-summer on.
Control: Fall sanitation; spray or dust with Karathane, phaltan, sulfur, or Acti-dione.
Rusts
Rusts form yellow, orange, orange-red, reddish brown, chocolate-brown, or black powdery pustules on leaves and stem. Leaves may wither and die early. Plants may be stunted.
Control: Sanitation; spray or dust with zineb, maneb, ferbam, or sulfur.
Leaf, stem, and bud nematodes cause leaves like those of begonia and chrysanthemum to show dark, angular, or wedge-shaped areas.
Bottom leaves wither and die first. Lily leaves are bronzed, blotched, and curled tightly downward (bunchy top). Phlox plants are stunted and die early. Leaves are spindly or wrinkled and curled.
Control: Buy clean stock; practice sanitation; if possible, keep water from splashing on foliage.
Wilts
Wilts may be caused by soil-borne fungi (fusarium or verticillium) or bacteria. It may be confused with root- or stalk-feeding insects, crown or root rots, and other troubles.
Control: Sanitation; six-year or longer rotation with non-related plants; use disease-free seed and planting stock; grow in well-drained, clean soil; grow wilt-resistant China asters.
Controlling Rots
Stem and crown rots, damping-off, and stem cankers cause seedlings or older plants to be stunted and sickly; they may later wilt and die.
The base of the stem is often discolored and rotted. Cankers on stems may cause foliage beyond to wilt and die.
Control: Plant in well-drained, clean, or sterilized soil; avoid overcrowding and overwatering; practice rotation and sanitation; drench soil with captan, thiram, phaltan, or zineb; follow regular spray or dust program using captan, zineb, maneb, phaltan or thiram.
Root rots, decline, bulb, and corm rots, and nematodes cause plants to gradually or suddenly lose vigor. Maybe stunted and sickly; wilt in dry weather may die. Affected plants do not normally respond to water and fertilizer.
Roots and other underground parts decayed, largely absent, or covered with knotty galls. Complex problems are easily confused with wilts, crown rots, soil deficiencies, root-feeding insects, and overwatering.
Control: Plant disease-free seed or planting stock in well-drained, clean, or sterilized soil; rotate crops; practice sanitation; keep plantings growing vigorously.
Tulips, lilies, and other bulbs are often soaked in hot water and formaldehyde by the commercial grower before you purchase them. Nemagon and Fumazoni may be used around most plants infested with nematodes.
About Crown Gall
Crown gall causes soft and spongy or hard, swollen galls, usually at or near the soil line and graft union. Maybe flesh-colored, greenish, or dark.
Affected plants become stunted and sickly.
Control: Carefully dig and burn diseased plants; rotate; plant disease-free stock; common rose problem.
44659 by Malcolm Shurtleff And William Luckman