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Natural Pest and Disease Control in your Vegetable Garden

Controlling pests organically means much more than simply changing the types of sprays and dusts you use. Organic gardeners aim to create a balanced system where pests are regulated naturally and where there is seldom the need to use even the safest organic sprays and dusts.

One of the principles at the heart of organic gardening is to completely eliminate the need to use sprays and dusts, even organically acceptable ones. While this might seem foolish — or even impossible — at first, by removing the need to continually spray and dust your garden, producing your own food becomes more enjoyable, safer and will require less work. This means more time spent admiring and eating the fruits of your labour, and less time spent preparing concoctions and potions!
So where do you start on the road to organic, pest-free self-sufficiency? Surprisingly, some of the best ways to contol pests and diseases don’t at first glance appear to be controls at all. By looking at her vegetable garden as a mini ecosystem which needs to be kept in balance, and thus in which no pests or disease can get out of control, the organic gardener is able to concentrate her efforts on:

  • cultural techniques which will keep her vegetable plants in the best of health
  • developing rich, biologically active soil
  • encouraging a diverse population of predator species to keep insect pests in check

But the place to start, and the foundation of your future organic vegetable growing success, starts with the plants themselves.

Buying healthy plants

Starting out with the healthiest plants you can find is a good way to ensure a healthy and productive vegetable garden. Use these tips to choose the best plants you can find:

Buy from nurseries or market stalls where the plants are well cared for. Plants which are allowed to stand in the sun on a hot pavement or which have been allowed to wilt are not a good choice, even if they’re cheap.

Look at the entire selection of plants on offer. If some of the plants appear to be in poor health, it may be that the healthier looking ones have arrived more recently from the supplier and have yet to succumb to the seller’s mistreatment. They might look healthy today, but could very well be diseased tomorrow.

Carefully look at the plant’s colour. Plants which appear slightly pale might just need to be fertilized, and this is easily corrected. But plants which have distinct yellow streaks or brown spots are diseased. Do not buy them, or any other plants in the selection.
Look for roots, and look at the roots if possible. Plants which have masses of roots growing through their container’s drainage holes have been left in too small a container for too long, and this could result in sever transplant shock if much of the root mass needs to be boken off in order to remove the plant from its container before transplanting. If you are able to (and if you are buying large quantities of plants, insist that you be allowed to) gently shake a plant loose from its container so that you can exmine the roots. The roots should be plentiful, but not wrapped in a tight spiral or almost filling the container.

Cultural techniques

Water early: If you irrigate your garden with a sprinkler from overhead, it’s best to water early in the day so plants can dry off before night falls. Foliage that stays wet for long periods of time is susceptible to leaf diseases, fungi that grow on leaves, tender stems, and flower buds. This tends to be a problem when plants stay wet throughout the night: Fungi spread quickly during the cool, moist evening hours. The fungi will cause the plant to be weakened, flowers will fall off, and fruit will begin to spot and become soft

Crop rotation: 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. Design your garden so that each family of vegetables — cabbage family, cucumber family, and tomato/pepper family — can be moved to another block of your garden on a three-year rotation.

Avoid monocultures: Planting a wide variety of plants in your garden is another way to foil pests and diseases by encouraging diversity. Conventional lawns are an excellent example of a monoculture. Planting a mixture of lawn grasses will help prevent diseases from sweeping through your lawn, because some grasses will be susceptible and others won’t.

Companion planting is another way to use diversity – and avoid monocultures – to foil pests. Mixing marigolds and herbs in and between your vegetable plants, as opposed to planting solid blocks or rows of a single vegetable crop, is very effective, because many pests locate crops by smell and these strong-smelling plants can “hide” a crop by masking the odour which attracts insects.

Developing rich soil

Soil that is fertile, well-drained and teeming with communities of a diverse range of micro-organisms will greatly increase your vegetable garden’s health and productivity, since many pests and diseases spend part or all of their lives below-ground. Having a diversity of microbes in the soil will help keep them in check.

Healthy soil is an intricate mix of tiny rock particles, organic matter, water, air, fungi, micro-organisms and other animals. The more organic matter you add to your soil, the more biologically active your soil will become, and the more active it is, the greater the competition between benign micro-organisms and those intent on doing harm to your plants.

Over time, adding organic material improves the soil’s structure, which in turn improves its ability to absorb and release water, thereby maintaining ideal moisture levels. Although rich, well-fed soil is all most vegetable plants need to keep them growing vigorously and producing well, fertilizing them at the correct time is also beneficial, and will help boost their natural resistance to pests and disease.

As a general rule, annual vegetables should be well-fed when they are young, and then given “booster” feeding when they start producing. Perrenial vegetables should be fertilised during the first third of their active growth in spring. You can also fertilise them in summer, but not in autumn, as late fertilisation can stress them by encouraging tender new growth which may be winter-killed. When you apply fertiliser, always keep in mind that more is never better. Over-fertilisation leads to rank, spindly growth which always worsens problems with aphids and some other pests.

Encouraging predators

Encouraging a diverse community of insect predators is one of the best ways to manage pests. Beneficials, the term used for insect predators and parasites, play a vital role in the complex community which naturally exists in your garden by eating or parasitizing harmful pests.

The first and most important rule for the gardener who wants to encourage beneficial insects is to immediately stop using toxic sprays and dusts. Even organic pesticides kill indiscriminately, so use them only when absolutely necessary and then only on the plants being attacked.

To attract beneficial insects into your garden, provide them with an attractive food supply. Since the adults of many beneficial insects only feed on pollen and nectar, the best way to attract them is to plant small-flowered plants such as dill, fennel, parlsey and mint.You can also allow a few of your vegetables, especially members of the mustard family such as radishes, and broccoli to go to flower. There are also many ornamental annuals which can be used: simply use them as colourful borders or edging plants around your vegetable beds.

Once the adults of beneficial species have arrived in your garden and had a good meal, the females will search for good places to lay eggs which will hatch into predatory larvae. Beneficial ground-dwelling insects such as beetles find refuge in the soil, under stones and in thick mulches.

It is important to minimise dust and to provide a source of water in hot, dry areas to protect beneficial insects, which are easily killed by dehydration. An old birdbath filled with water and rocks (to provide safe landing places and prevent drownings) will be used by many beneficial insects.

Birds are amongst the most efficient predators of harmful insects, so planting shrubs and trees, and supplying them with a source of water to attract them to your garden – and encourage them to stay and eat their fill! – is a worthwhile investment.
And for consuming slugs, cutworms and many other ground-dwelling pests, nothing beats frogs and toads. Be sure to provide shelter and water for them, too.

Non-Toxic control of Insects

There are many different non-toxic control methods we can use against insects in the garden. Some are commercial sprays and powders, others can be made at home from household ingredients.

Use non-toxic insecticides only when absolutely necessary The following list of non-toxic insecticides should only be used whco absolutely necessary. It’s important to allow the garden to develop it’s own micro-divcrsily and ccology.

Bacillus Thuringiensis
Of the micro-organisms that make insects ill, Bacillus thuringiensis is by far the best known. Though safe to humans, it has a devastating effect on many pests. BT, as it is often called, appears on the market in the form of a soluble powder. The powder is suspended in water and sprayed on plant surfaces, where it is ingested by the pest. The BT spores then germinate into plants that occupy more and more of the victim’s body. A toxic crystal is also produced and is thought to be partially responsible for the insecticidal effect. BT is useful on both vegetable and fruit crops, aiding in the control of caterpillars, earworms, peach tree borer, cabbage moth, cabbage looper, and gypsy moth caterpillar.

Pyrethrum A is a botanical insecticide derived from the flowers of a species of chrysanthemum. The material causes rapid paralysis of most insects, but the insects usually recover unless the pyrethrum is combined with a synergist or other poison. There are several pyrethrmun products available that are certified organic. Use against aphids, thrips, caterpillars, ants, flies, earwigs, cabbage moth. As pyrethrum also affects beneficial insects it should only be used as a last resort.
Wettable Sulphur ia an effective fungicide and miticide. The sulphur interferes with important processes in fungal spores and is noted for its ability to suppress mite populations.

Other non-toxic pesticides
Gardeners have been using soap to control insects since the early 1800s. During the first half of thc 19th century, whale oil soap and, more commonly, fish oil soaps were an important part of insect control. Recent tests indicate that a good quality environmentally friendly dishwashing detergent, diluted with water to a 1 to 2% solution, provides the most consistent control and is easy to mix. There are also soaps available that are specifically formulated to control insects on plants. Thorough coverage of the plant and repeated applications may be necessary to bring insect populations under control and may damage some plants.

Barrier bands are wrapped around the trunks of fruit-bearing trees to prevent crawling insects and larvae from reaching the fruit and foliage. The insects will hibernate in the bands, which should be removed and burned. (Do not bury or compost). Tie corrugated paper, cotton, or sacking around the trunk. This is very useful against many damaging moth species.

Compost tea

Manure and compost tea is effective on many pests because of the micro-organisms that exist in it naturally.

How to make compost tea: use any container, but a plastic bucket is easiest. Fill half full of well-made compost and fill with water. Leave for 10 to 14 days, then dilute the tea concentrate to approximately 1 part tea to 10 parts water, straining out the solids with old pantyhose or cheese cloth. Spray on the foliage of any and all plants including fruit trees, perennials. annuals, vegetables, roses and other plants, especially those that are regularly attacked by insects or fungal pests. Compost tea is a very effective control for early blight on tomatoes.

Garlic/pepper tea

To make garlic/pepper tea, liquify 2 bulbs of garlic and 2 hot chillies in a blender with a cup of water. Strain the solids and add enough water to make 4 litres of concentrate. Use 1/4 cup of concentrate per 4 litres of water. To make garlic tea, simply omit the pepper and add another bulb of garlic. Add two tablespoons of molasses for more control.

Garrett Juice: (Ready to spray)

One cup compost tea, one large tablespoon molasses, same of natural apple cider vinegar, same of liquid seaweed.

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