Gardening Tips: The organic approach

Organic gardeners are those who do not use chemical fertilizers, pesticides, fungicides or herbicides, and this section deals primarily with the organic approach to controlling major pests and diseases, and improving your soil.

Some gardeners give up using chemicals because they prefer the flavour of compost-grown produce, some because of the damage to the environment from persistent pesticides, especially to wildlife and bees, and the extremely harmful effects of excess nitrates from fertilizers and other chemicals that are washed into lakes and rivers, while others ‘go organic’ purely on cash grounds. The nine-fold rise in the cost of phosphate fertilizers in recent years has underlined the fact that all chemical aids to horticulture and agriculture depend on petro-chemicals and the price of these is likely to double and redouble as the years go by. Also, most fertilizers are just as exhaustible as fossil fuels, as neither can be renewed once they are all used up.

From a purely practical point of view, if there are any ways of controlling pests or building up fertility in the soil without spending money, they are always worth using. The ideal methods for organic gardeners are those that do not involve any sprays, however safe these may be for the birds and the bees, because it is just as much work to spray with an organically based solution, such as derris or pyrethrum, as with any other type, such as malathion.

Here, we give a selection of some of these methods.

The runner bean trench

A good way of improving your soil without using chemical fertilizers is to make compost in your runner bean trench. Dig the trench 60 cm (2’) or more wide and at least 30 cm (1’) deep in mid-autumn or early winter. During the winter, fill this with all the spent Brussels sprouts and cabbage stumps to a depth of 15 cm (6”) and then empty kitchen wastes on top, covering each bucketful with soil to prevent rats, dogs, cats or birds from eating it. The bulky sprouts and cabbage stumps can be a problem in winter when there is too little other compost material to heat them and break them down fast, and the bean trench is a good answer. The nitrogen-fixing bacteria in the roots of the beans behave as an activator, and, in effect, one is making a long, narrow compost heap.

Plant or sow the runner beans as usual in late spring, after filling up the trenches and treading the material firm, because by then this compost will have sunk. By the time the beans have climbed high up their sticks, its further decay will have left plenty of room to fill up the trenches with water from a hose, for by now the material will have sunk further. Do not hose the foliage, because runner beans were imported first as half-hardy annual climbers and the shock of the cold water can make them drop their blossom.

When the crop is cleared, the brassica stumps will have broken down to good humus, and as you rotate your runner bean rows round the garden, each area in turn has deep digging and lasting fertility from stumps that would otherwise be burnt.

Mealy cabbage aphis and cabbage whitefly spend the winter as eggs on the stumps of cabbages, Brussels sprouts and other brassicas. Those gardeners who leave the tops of their Brussels sprouts on the plants to grow ‘spring greens’ are making sure of more pests next year, but the bean trench destroys both sets of eggs so effectively that if more gardeners used this trick it would go a long way towards reducing the numbers of these two pests.

Pest control by ladybirds

The cabbage aphis is a favourite food of the seven-spot ladybird, and so nutritious that it helps the ‘hen’ ladybird to increase her egg production from an average of 120 eggs to nearer 700. The larvae of ladybirds, which look rather like tiny, six-legged crocodiles, also eat large quantities of aphids. Ladybirds are completely harmless, so leave them alone to clear up as many aphids as possible. Whenever we have too little rain in early summer to batter down the migrating winged stage of the aphis, it spreads from farms to gardens, and the ladybirds spread with it, increasing to produce the record swarms that carpeted pavements in 1976 and 1977. Their rich diet of aphids also puts weight on the ladybirds, producing outsize individuals that have a far greater chance of surviving the winter.

It is never possible for ladybirds to control the pests completely, but with enough of these attractive beetles in the garden, the autumn slaughter of winter and spring cabbage by aphids can be beaten.

Hoverfly larvae, which look rather like small but active slugs, also kill aphids. The adult hoverflies lay their eggs among the aphid colonies and when these eggs hatch out into the larvae, they feed on the aphids. None of these predators which control garden pests ever ‘eat themselves out of a job’ and it costs nothing to have them in the garden, yet it is only when inorganic gardeners destroy them by toxic sprays that we realize how much work they do on our behalf.

Safe pesticides

Although derris and pyrethrum are safe for all warm-blooded creatures, both kill ladybirds and bees just as effectively as they destroy harmful insects; also, derris is deadly to fish. Perhaps the best of all ‘safe’ pesticides is nicotine, which spares insect predators, but it is now hard to obtain.

The easiest way to ensure a supply of nicotine is to buy 30 g (1 oz) of pipe tobacco and simmer it for 15 minutes in 4.5 L (1 gal) of water. Let it cool, strain it and then dissolve 30 g (1 oz) of soft soap paste in another 4.5 L (1 gal) of cold water, mix the two solutions, and spray as required.

A cheaper trick is to collect 120 g (4 oz) of filter-tip cigarette ends and use them instead of the pipe tobacco. However, do remember that nictoine is very poisonous to human beings, so keep it off your hands, and if you do keep the solution in a bottle (where it will last 2-4 weeks), label it clearly ‘POISON’.

The safest method is to boil up cigarette ends as required, for no-one will mistake your hoarded tinful for a soft drink, as many people (and particularly children) have done with a number of deadly proprietary pesticides.

Nicotine is a good all-round pesticide for use against aphids, caterpillars, capsids, weevils and almost anything else you need to kill, with the great advantage of being cheap enough to use generously. The only cost you will be incurring is that of the soft soap with which the nicotine solution must be mixed.

Nicotine breaks down within 48 hours, so you can eat cabbage or other crops sprayed with nicotine perfectly safely after this period has elapsed. This also means that there is no build-up of the substance in the soil. It is poisonous to fish, so make sure none finds its way into fish ponds or streams. It will kill birds and other wild animals only if they drink it, which is most unlikely.

A safer substitute for nicotine is quassia chips, which keep indefinitely. Simmer 30g(l oz) of these in 1.1 L(2pt) of water for half an hour, topping up the solution with more water as it boils away. Add 30 g (1 oz) of soft soap paste, and dilute the mixture when cool with a further 3.4 L (6 pt) of water. This makes a good aphid spray, and will also kill sawfly caterpillars, such as the green, black and orange ones that attack gooseberry bushes, but it is too weak for general use.

The soft soap is to help the nicotine or quassia penetrate the waxy coats of pests. Quassia has a very bitter taste, so you should not use it on leaf crops that are going to be eaten within two weeks of spraying.

It is most important to use genuine soft soap, which is made with potassium carbonate, not caustic soda (sodium hydroxide), and is much more powerful in its penetrating effect.

You can spray with soft soap alone: in this case, dissolve 60 g (2 oz) in 4.5 L (1 gal) of hot water, allow to cool, and use the solution to spray cabbage white, cabbage moth and other caterpillars, and also cabbage whitefly larvae, with the great advantage that it is entirely non-poisonous to human beings, pets and beneficial wild animals. Soft soap of the industrial grade can sometimes be bought from ironmongers or chemists to order, but higher quality soft soap, although more expensive, is always available from chemists.

Herbalists or the more old-fashioned chemists stock quassia, and there are a few horticultural nurserymen who also supply it.

31. August 2013 by admin
Categories: Fruit Gardening, Uncategorized, Vegetable Gardening | Tags: , , , , , , , | Comments Off on Gardening Tips: The organic approach


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