First of all, you can take the simple precaution of planting only varieties that are not susceptible to major pest problems. There are a lot of vegetables that pests usually don't attack, or don't attack in large enough numbers to cause you any real grief or require the use of nonorganic methods of control. All these are fairly problem-free vegetables: artichokes, asparagus, beets, carrots, celeriac, celery, chard, chicory, cucumbers, dandelion, horseradish, Jerusalem artichokes, leeks, okra, onions, parsnips, peas, radishes, rhubarb, salsify, soybeans, spinach, turnips, and almost all the herbs.
Some vegetables are almost always attacked by caterpillars that can be controlled by Bacillus thuringiensis, an organic product that is harmless to humans and animals. These include all the cabbage family plants — broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, and kohlrabi. The other insects that commonly attack the cabbage family plants can also usually be controlled by natural and physical methods.
Some vegetables are almost always attacked by large numbers of insects that cannot be controlled by natural or physical methods. This is not to say that you can't grow these crops without using pesticides; you can, but usually your yield will be low. These vegetables include most of the beans, Chinese cabbage, sweet corn, eggplant, lettuce, mustard.
peppers, potatoes, pumpkins, rutabagas, sweet potatoes, tomatoes, and watermelons.
Squash are not included in any of these categories, because although the squash vine borer— their main enerpy—cannot be effectively controlled without using a pesticide, most squash are prolific enough to give you an acceptable crop even If you do lose some to bugs.
Sidestepping pest problems by planting vegetables that are least likely to be seriously threatened by pests is one practical way to protect your crop. Another is the physical, do-it-yourself method of removing the offenders by hand. If you're going to do this, it's essential to identify pests in the early stages of their attack. It's not a big deal to pick a couple of dozen aphids off your broccoli; but when the attack is well under way and your plant is covered with aphids, you might as well forget about hand-picking, because it's not going to work.
If you slip up and let a pest problem get past the early stages, you can try a good blast of water from the garden hose to knock the insects off the plant. Try to do this on a dry day so that the leaves won't stay wet for too long; wet leaves make the plant more susceptible to disease and may give you a new problem to replace the one you've just solved.
Other physical control methods can be effective with specific pests. These methods are discussed in detail later in this chapter.
These have to be the original "organic" ways of controlling pest problems in the garden — you're simply relying on harmless insects to destroy the harmful ones. The effectiveness of these natural methods of control is questionable; in some cases you're probably just perpetuating old wives' tales. It's true that insects like ladybugs, lacewing flies, praying mantises, and aphis lions feed on bugs that are destructive to your crop and should, therefore, be protected when you find them in your garden. But it's also true that they can't offer a complete answer to a pest problem. If these helpful creatures visit your garden, welcome and protect them. But don't expect them to control all the pests that bother your plants. That's asking too much of them.
It's possible to buy ladybugs, praying mantises, and the like through the mail from garden supply companies. However, you're likely to be wasting your time and money by doing so. All these insects are winged, and they're all very shy of people. The odds are they'll wing it away as fast as you put them out, deserting your vegetable garden for a more secluded spot. Also, the beneficial Insects that you import may not consider the specific variety of pest that you have in your garden to be a particular delicacy. In this case they'll fly off in search of more appetizing fare. Either way, they're likely to let you down as far as solving your pest problem is concerned.
When you're talking about pest control it's an advantage to group the types of pest you may encounter in categories: Some work at night; some work underground; some chew the plant's leaves; others bore into the stems. The following is a list of pests you're most likely to meet in your vegetable garden, and chemical and nonchemical controls for each insect.
Underground and nocturnal pests
The pest you can't see can be the hardest to deal with. The following creatures work underground or at night, so you don't know they're around until the damage they do is visible.
Root maggots. Maggots are fly larvae. They are yellowish-white, legless, wormlike creatures (a quarter to VA inches long) that feast on roots and stems just under the soil's surface. The best nonchemical control is prevention. Discourage the fly from laying eggs near the seedlings by putting shields of plastic three or four inches square around each plant. Take care not to cover the paper with soil when you cultivate. Root maggots attack
beans, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, radishes, spinach, squash, and turnips. You can control them chemically by drenching the soil around the plant that's under attack with Diazinon. Don't spray until you see the damage; if your plants are growing poorly, and you can't figure out why, root maggots may be the cause.
Wireworms. Wireworms are slender, hard worms about an inch long. They eat the seed in the ground and feed on underground roots and stems. After doing their damage, which appears as poor-growing, yellow, wilted plants, they grow up into click beetles. To control wireworms, apply a soil drench of Diazinon when the wireworms are present.
Chewing pests are usually easy to find, especially when they have put in a good clay's work, and they're easier to control by nonchemical methods than the nocturnal and underground pests are. Many of them can be hand-picked off the plant or knocked off with a blast from the hose. Almost every chewing insect that feeds on the outside of the plant can be controlled chemically by using carbaryl. Check to make sure that you have identified the guilty party; apply insecticide when the pest is first discovered, and repeat the treatment as often as necessary according to the directions on the label.
Asparagus beetles feed on asparagus; Mexican bean beetles love beans. Blister beetles feed on beans, beets,chard, corn, potatoes, tomatoes, and squash. Cucumber beetles (spotted and striped) often attack melons, pumpkins, squash, and watermelon, as well as cucumbers. Their eating habits may not cause much damage, but they carry cucumber bacterial wilt, which will kill any of these plants when they're older. Flea beetles will eat almost any garden crop. They're very small, and it's difficult to spot them, but you'll know they're there when tiny black dots jump from the plants when you come near, and when you notice that the leaves of your vegetable plants are suddenly full of small holes scattered over the entire leaf surface. Potato beetles chew on eggplants, potatoes, and tomatoes. If there are too many small beetles to hand-pick, try to hose them off. All these beetles can be controlled chemically with carbaryl, used according to the label directions.
Borers (squash vine borers). Cucumbers, melons, pumpkins, and squash are attacked by this borer. The egg is laid on the outside of the stem by a night-flying moth. The eggs hatch, and the borers tunnel inside the stem of the plant. As they grow inside the stem, they eat it out, and eventually the plant wilts and dies. Watch for the warning signs: stunting or unexplained wilting of the plant or — this is the surest evidence of who the culprit is — a small hole at the base of the plant and a scattering of sawdustlike material around it. A chemical control of carbaryl needs to be applied at weekly intervals to the crown of the plants before the borers get inside the stem. Once the borer gets inside the plant chemical controls will not help. You can control them physically if you slit the stem, remove all the borers, and cover the spot with earth to encourage root growth at that point. This attempt at a cure may have the opposite effect and kill the plant. But it's your only chance to get rid of the borers.
Cabbage loopers and cabbage worms. These caterpillars love to feed on all members of the cabbage family; occasionally they will make do with lettuce. To control them, spray with Bacillus thuringiensis, an organic insecticide that is available under a number of trade names including Dipel, Thuricide, and Bactur. This is a completely safe organic spray that will destroy the caterpillars without harming humans or animals.
Corn earworms. These caterpillars prefer corn, but they also feed on beans, tomatoes, peppers, and eggplant. They are also called tomato fruitworms. To effectively control them, be prepared to spray on a regular schedule with carbaryl. Hand-picking and cutting out the damaged parts of the vegetables will give limited control of this pest.
Parsley caterpillars. These feed on parsley, dill, fennel, and other members of the parsley family. They're not common enough to be a major problem, and hand-picking usually provides satisfactory control.
Leaf miners. Leaf miners are the larvae of a fly that feed on the external portions of a leaf. They will feed on cabbage and its relatives, and on chard, beets.
and occasionally lettuce. The best method of controlling the leaf miner is to remove affected leaves from the plant by hand and to hand-pick egg masses that can usually be found on the backside of older leaves. Since the leaf miner is inside the leaf surface, chemical controls are ineffective.
Slugs and snails. Snails have shells and slugs don't. Both are more closely related to oysters and clams than they are to insects. You can detect their presence by the slimy trail they leave from the scene of their activity. They don't like to be out in the heat of the day; they eat and run and can be hard to control. They like to feed on cabbage and all its relatives, and on carrots, lettuce, tomatoes, and turnips. To control them remove their hiding places — old boards, cans, bricks, and other garbage. Lay scratchy sand or cinders around each plant to discourage them. Or set a saucer in the soil with the
rim flush with the soil surface, and fill it with stale beer. The slugs and snails will be attracted to the beer and fall in and drown. Then you can dispose of them in the morning.
Aphids, leafhoppers, mites, and thrips may be hard to see. By the time their damage is apparent it is often too late to take much action. Watch for scraped and rusty-looking places on leaves, twisted and deformed leaves and leaf-tips, and stems that look unusually thick.
Spider mites. Spider mites are very small and difficult to see. You can be fairly sure that spider mites are to blame if the leaves are losing color in spots and turning yellowish, light green or rusty and there are silvery webs on the undersides. Spider mites are difficult to control even if you use the proper chemicals. You can spray the undersides of the foliage with Diazinon before populations get too large. If you don't want to spray or if the spraying is ineffective, remove the affected plants before the spider mites spread.
Thrips. Thrips are small, fast-moving insects that are almost invisible to the naked eye. The damage they do shows up first as white blotches, then there is a distortion of the leaf tips. When thrips attack onions.
they dwarf and distort the bulbs. Thrips also attack beans, beets, carrots, cabbage and its relatives, celery, cucumbers, melons, onions, peas, squash, tomatoes, and turnips. Large populations of thrips can be discouraged by hosing them off the plants. Thrips can be controlled chemically if you spray them with Malathion or Diazinon.
Whiteflies. Whiteflies are minute sucking insects that look like tiny white moths. They live and feed on the undersides of leaves and live unnoticed until you disturb the plant, then they fly out in great white clouds. Whitefly populations can be discouraged by hosing them off the plants. Control them chemically by spraying the undersides of the leaves with Malathion or Diazinon,
PLANT DISEASES: PREVENTION BETTER THAN CURE
A number of plant diseases are the result of unfavorable growing conditions, but many are caused by parasitic bacteria and fungi that cannot produce their own food and rely on the plant for nourishment. Some diseases are airborne, and others can live for years in the soil, so it's difficult for the gardener to predict or control them.
As a matter of policy, prevention is better than cure — or attempting a cure — where plant diseases are concerned. You can try to avoid the conditions that promote disease by choosing your planting sites wisely. Primarily you want to avoid the combination of too much moisture, too much shade, and soil that's too cool — the three conditions that provide an ideal environment for the propagation of diseases. You can also plant disease-resistant varieties, rotate crops, and take steps to keep your garden clean and healthy.
If your preventive measures don't work, you'll have to cut your losses. There's little you can do to save a plant that has been attacked by a parasitic fungus or bacterial disease, and your best bet is to remove the affected plant as soon as possible before the disease has a chance to spread to healthy plants. This may seem drastic, and you may be tempted to save the plant, especially if it's near harvesttime. Don't give in to temptation —you're risking the rest of your crop. Remove the diseased plant and burn it, put it in the garbage, or dispose of it elsewhere well away from your vegetable garden. Don't leave it lying around the garden, and don't put it on the compost pile.
Protecting your garden from disease
Maintaining a healthy garden requires you to be a conscientious gardener. Here are methods you can use to keep your garden free from disease:
Prepare the soil properly. Make it easy for your plants to grow well. Plant vegetables in full sun if you can; strong sunlight is a great disinfectant, and the energy plants draw from the sun gives them extra strength. Make sure the soil is well-worked, has good drainage, and is high in organic matter so the soil moisture will remain even. Do not plant the vegetables when the soil and air are too cold. Place plants far enough apart so to avoid crowding; this will allow good air circulation, and the plants will be able to dry out after a rain.
Select disease-resistant varieties. Where possible, buy seeds that are certified as disease-free. Use seeds that have been treated with fungicide, or start your seeds in a sterile soil mix. Your local Cooperative Extension Service can supply you with a list of disease-resistant vegetable varieties for your area.
Rotate your crops. Do not grow the same plant family in the same spot year after year. Repetition of the same crop gives diseases a chance to build up strength. There are three major vegetable families: cole crops (cabbage family) — broccoli, Brussels sprouts, cabbage, cauliflower, kohlrabi, rutabaga, and turnip; cucurbits (cucumber family) — cucumber, gourds, muskmelons, pumpkins, summer and winter squash, and watermelons; and solanaceous plants (tomato and pepper family) — eggplant, Irish potato, pepper, and tomato. After growing a crop from one of these families one year, choose a variety from one of the other families to plant in the same spot the following season.
Don't work with wet plants. Do not work the soil when it is wet. When you're watering the garden, try not to splash water on the plants, especially in hot, humid weather. Handling plants when they're wet spreads diseases.
Control garden pests. Keep insects and other small pests under control. Some insects spread disease; sometimes insects just weaken the plant so that it becomes more susceptible to disease.
,Don't infect your own plants. If you smoke, wash your hands well with soap and hot running water before working with tomatoes, peppers, and eggplant. Smokers can infect these plants with tobacco mosaic virus, causing them to mottle, streak, drop their leaves, and die.
Keep your garden clean. Always keep the garden clear of weeds, trash, and plants that have finished producing. Remove infected plants. If you have a sick plant in the garden, identify the problem. If it's a virus or fungus disease, remove the affected plant as quickly as possible. Destroy the plant; do not put it in the compost pile. This removal of infected plants Is called "culling." Don't think of it as killing a plant;
Lack of water Too much water
Stop watering; improve drainage; pray for less rain
Use disease-resistant varieties; keep your garden clean
Leaves and stems are spotted
Fertilizer or chemical burn
Follow instructions; read all fine print; keep fertilizer off plant unless recommended
Use disease-resistant varieties of seed; dust or spray; remove affected plants
Plants are weak and spindly
Not enough light Too much water
Plants are crowded Too much nitrogen
Remove cause of shade or move plants
Improve drainage; stop watering; pray for less rain Thin out
Destroy affected plants; rotate crops; grow disease-resistant varieties
Control aphids; destroy affected plants
Plants are stunted — yellow and peaked
Too much water Poor drainage
Compacted soil Too much rubbish Acid soil
Not enough fertilizer
Improve drainage; add more organic matter before next planting
Cultivate soil more deeply
Test, add lime if necessary
Test, add fertilizer (this should have been done before planting)
Plants are stunted — yellow and peaked (cont.)
Insects or diseases
Yellow or wilt disease, especially if yellowing attacks one side of the plant first
Identify and follow recommendations from your extension service
Spraying will not help; remove affected plants; plant disease-resistant seed in clean soil
Seeds do not come up
Not enough time for germination Too cold Too dry
Too wet, they rotted Birds or insects ate them Seed was too old
Wait — replant if necessary
Replant with fresh seed
Young plants die
Fungus (damping-off) Rotting
Treat seed with fungicide or plant in sterile soil
Do not overwater
Follow recommendations for using the fertilizer more closely; be sure fertilizer is mixed thoroughly with soil
Leaves have holes
Insects, birds, rabbits
Heavy winds or hail
Identify culprit and take appropriate measures
Plan for better protection
Tortured, abnormal growth
Herbicide residue in sprayer, in grass clippings used as mulch, in drift from another location
Use separate sprayer for herbicides; spray only on still days; use another means of weed control
Control insects that transmit disease; remove infected plants (do not put them on the compost pile)
Blossom ends of tomatoes and peppers rot
Dry weather following a wet spell Mulch to even out soil moisture
Not enough calcium in soil
Blossom ends of tomatoes and peppers rot (contj
There is no fruit
Compacted soil Too-deep cultivation
Weather too cold Weather too hot Too much nitrogen
Plants not mature enough
Avoid cultivating too deeply
Watch your planting time Same as above
Fertilize only as often and as heavily as needed for the variety
Pollinate with a brush, or by shaking plant (depending on kind); do not kill all the insects
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