Saturday, March 29, 2014

Survival Gardening: Pests, Diseases, and Weeds

There are "seven pillars of pest control" (with apologies to Lawrence of Arabia). These rules mainly apply to the control of insects, but roughly the same rules can be applied to the control of more primitive forms of life: fungi, viruses, bacteria, and mycoplasmas.

(1) Selection: Choose resistant species and varieties.

(2) Diversity: Grow a fair number of species and varieties at the same time (avoid monoculture).

(3) Rotation: Do not grow a crop in the same place in the following year.

(4) Health: Keep your plants strong by providing good soil and enough water, light, and space.

(5) Sanitation: Remove and burn any dead or dying plants, and avoid touching wet plants.

(6) Tillage: Dig up the ground each year to destroy insects.

(7) Attack: Fight insects by handpicking or by applying natural insecticides (wood ashes on the leaves for flea beetles [or on the ground for cabbage-root maggots], soap spray for cabbage-butterfly larvae, garlic spray for aphids).

A common disease problem is the white mildew that can spread over vegetables in the late summer or in unusually damp weather. To prevent such a problem, maintain a good distance between plants, don't sow them in shady areas, and don't touch plants when they're wet. If you supply water to your vegetables, put it on the roots, not the leaves. Try not to touch plants that have mildew, but if you do so then you should wash your hands before touching healthy plants. Mildew is mainly a problem later in the summer, when most of the crops will have been harvested already, so there may little to worry about. If diseases become serious, the best thing is to remove all the affected plants and burn them or bury them.

Insects and other small creatures can cause trouble in a garden. The best cure is prevention: always keep the garden soil in good condition, because good soil produces healthy plants, and healthy plants are more resistant to bugs. If you do get insects on your plants, you can often just pick them off by hand. Don't worry much about insects getting some of the young plants; there's not much you can do about it, and they will give up as soon as the plants have grown a few inches tall. If insects are really causing havoc with cabbages or similar crops, you might want to plant more thickly and just allow the insects to take their portion.

There is evidence to suggest that garden pests are more common than they were 50 or 100 years ago. Problems caused by such creatures as the Colorado potato beetle or the European corn borer seem to represent a new stage in the history of agriculture. Admittedly, there are many methods for dealing with pests, even without resorting to poisons -- maintaining good soil, using good rotation systems, hand picking, spraying with garlic or pepper, and so on -- but the fact that such a struggle is going on seems to suggest that the war has escalated over the years. Government studies seem to reach no definite conclusions about a possible increase, mainly because of the lack of solid data from the past, but even generalized descriptions of earlier times can leave one a little pessimistic.

Many books and articles have been written in or about pioneer times, and also about the agricultural methods of the native peoples. Very few of those documents say much about insect pests, however, except to mention that locusts created serious trouble for pioneers on the prairies. Perhaps, in describing earlier conditions, the historians and anthropologists have simply forgotten to mention pests -- perhaps it never occurred to them as a subject worth mentioning. But that seems unlikely. A more likely explanation is that pests were less frequently encountered in those days.

If it does turn out that pests are more common, we are then left with the further question of why this has happened. One problem, of course, is that insects have become resistant to chemicals, but that fact not would explain why they would be more common in the first place. The most likely three main causes of such an increase would be: the arrival of alien species (as in the case of the "European" corn borer), which attack plants that have no natural resistance; the decline in the practice of crop rotation; and the spread of monoculture.

If you water your crops, you can do it either in the early morning or in the evening, but early morning is better. If you water in the evening, you might be letting water stay on the plants too long, thereby encouraging insects and slugs. In any case, try not to water at midday, particularly on a hot summer day, because the water will just evaporate.

Birds and animals can do a lot of damage. Birds especially like anything with grains or seeds; if your crop is large enough, you may be safe, but for a small patch you may need to erect a net. Woodchucks enjoy eating young crops of various sorts, whereas deer prefer young corn. Always grow more than you need, so that predation by animals won't ruin you. You can discourage woodchucks by putting mothballs or creosote in their burrows. If you have the money and time, you can put a fence around your garden: a 6-foot (2 m) fence will keep out deer if they can't see through it, but it will have to be 10 feet (3 m) high if they can see what's on the other side. That same fence will have to extend a few feet into the ground if you want to keep burrowing animals out. Plastic (polypropylene) deer netting, a floppy and therefore discouraging material, may be cheaper than wire fencing, and easier to set up. Don't "make friends" with wild animals; no matter how cute they are, that friendship is entirely one-sided, and they'll be back the next day to eat their way through your garden.

The biggest summer job, especially on a new patch of ground, is keeping the weeds under control. To save labor, eradicate them while they're small, preferably before they're even visible. Pulling up weeds by hand is sometimes more efficient than any other method, especially when they're close to your vegetables, although a hoe is better on the main stretches. The seeds of some weed species will stay in the ground for years before a little human disturbance wakes them up, so don't be surprised when weeds seem to appear out of nowhere. Most weeds will die pretty quickly after they've been dug up. Purslane, unfortunately, actually thrives from being chopped up and exposed, so you may need to rake it into piles and leave it far from any soil or compost heap.

Low soil fertility is one of the main causes in the growth of certain kinds of weeds. Soil that is rich in organic matter allows the growth of more desirable plants. Rich soil also contains bacteria that make weed seeds lose their viability.

Weeds can sometimes be valuable. They add organic matter to the soil, bring up important elements from the depths, and often take nitrogen from the air and put it into the soil. Weeds can break up hard soil and improve the soil's ability to absorb air and water. Many weeds are also edible; they are the ancestors of cultivated crops, and others may become crops in the future.

Because different weeds grow in different types of soil, you can use the weeds that grow on your land to tell you a lot about it.

If most of the trees are evergreens, the soil is acidic. Acidic soil is also indicated by bramble, cinquefoil, corn spurrey, dock, hawkweed, knapweed, low star grass, sheep sorrel, swamp horsetail, or wild strawberry. Slightly acid soil is indicated by daisy, dandelion, dog fennel, doorstep weed, garden sorrel, horsetail, mayweed, or plantain. On the other hand, limestone soil will support Canada blue grass, chicory, field peppergrass, field madder, mountain bluet, penny cress, teasel, wormseed, or yellow camomile.

Alkali soil (soil containing alkaline salts) occurs in parts of the southwestern United States, and on it you are likely to find common spikeweed, goldenrod, kochia, nitrophila, pickleweed, salt grass, saltbushes, saltwort, samphia, sesuvium, tussock weed, or yerba mansa.

On sandy soil you will probably see broom bush, goldenrod, many-flowered aster, onions, partridge pea, wild lettuce, or yellow toadflax. On deep clay, the opposite type of soil, you might find selfheal and wild onion.

Dry land, and also land that is low in organic matter, will support devil's paint brush, spurge, mosses, lichens, and poverty grass. On the other hand, land that is excessively wet due to poor drainage will be growing buttercup, cattail, creeping Charlie, ferns, hedge bindweed, hedge nettle, horsetail, ironweed, Joe-Pye weed, loosestrife, March foxtail, meadow pink, pennywort, rice cut-grass, rush, sedge, silverweed, smartweed, stinking willie, swamp horsetail, or tradescantia.

Tight, compressed land will grow bluegrass and knotweed. Hardpan, soil that has become cemented together and is impervious to water, will grow camomiles, field mustard, horse nettle, morning glory, penny cress, pineapple weed, or couch grass

Other weeds may be indicators of high-quality soil: burdock, dock, amaranth, lamb's quarters, purslane, ragweed, or thistle.

Peter Goodchild

Author of Tumbling Tide: Population, Petroleum, and Systemic Collapse (London, Ontario: Insomniac Press, 2014)

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