Garden Pests – Non-Chemical Control

Garden Pests

Non-Chemical Control

Much the same goes for the control of pests; the radical course of action is often the best-if you can pick off the offender, do so and tread on it. If you’re squeamish then you have to close your eyes and squash it where it is. There is no point in being faint-hearted about it; use your fingers or, if you cannot stand that, put on some gloves. Whatever ‘method’ you adopt, the result is the same – a dead pest that will cause you no more bother.

This essentially physical approach to the problem of pest control is not to everyone’s liking but there is no denying that two half-bricks administer a considerably quicker, more humane and more definite end to slugs than does a sprinkling of salt. However, slug traps consisting of sunken jam jars half filled with beer are a good compromise. They’re effective, clean and non-chemical.

Garden Pests - Non-Chemical Control Caterpillars, too, are very quickly disposed of by picking them off the plants individually and destroying them as you think best. Treading on them is definitely terminal and not too distasteful.

Another non-chemical control concerns the cabbage root fly. This is the pest that lays its eggs at soil level, these hatch out and the young grubs eat away the roots, causing the collapse and death of the plant. Soil insecticides are available forthis but a non-chemical control is to place collars round the neck of transplanted brassicas. These can be bought or made from old felt, about 4in (10cm) across. Cut a slit to the centre of the disc and slip it round the neck of the transplanted plant. The fly can’t now lay its eggs against the stem so it goes elsewhere.



Old Wives’ Tales and Natural Controls

Amongst what might be termed ‘alternative’ methods of combating this, that and the other nasty, come the old wives’ tales. They shouldn’t be taken too seriously, but nor must they be totally ignored because, if all else fails, they could well work and solve the problem.

Many books have been written about these sometimes rather bizarre methods of preventing or banishing problems and they are certainly worth reading. It does not always do to take them too seriously, though, as some are very definitely written tongue-in-cheek. On the other hand, they must all be based on fact or they would not have survived so long and held such wide acceptance.

Here are a few to get you thinking. ‘To keep club root disease away from brassicas, bury a stick of rhubarb near the crop’ I cannot follow this one at all. Club root is a disease that is encouraged by acidic soil conditions and anything more acidic than rhubarb is hard to imagine. The best control of club root is certainly to reduce the acidity of the soil by regular applications of chalk or lime.

‘To get rid of peach leaf curl, pick off the infected leaves and hang mothballs or naphthalene anti-moth rings in the trees’. Never tried this myself, but it seems odd that an insecticide should also be effective against a fungus disease. Still,this is not unheard of and a coal-tar derivative (naphthalene) would certainly have the properties of a steriliser.

There are many more reputed remedies for pests than there are for diseases, one of the best known being garlic against greenfly. The normal recommendation is to plant a garlic clove amongst the plants you want to protect. Something within the garlic is exuded into the soil and then absorbed by the roots in much the same way as is a systemic insecticide. Apparently, garlic only smells when in flower so, provided that you take the precaution of removing the flower heads as soon as they appear, there should be no bother. Other members of the onion family are said to be effective, but not to the same extent. Chives would probably look the least out of place of any.

Another quite well-known remedy is French marigolds (or any other Tagetes) in the greenhouse to keep whitefly away from tomatoes and fuchsias. A lot of people still swear by this, so it is well worth a try. Another possible cure for the same problem is nasturtium plants.

Nasturtiums are also allegedly a good cure for woolly aphis in apple trees. I find this particularly hard to swallow as nasturtiums frequently get plastered with blackfly themselves, and woolly aphid is simply another variety of the same pest.

If you believe the next one, you will believe anything. ‘Caterpillars originate in Tartary to the east of the Caspian Sea and are carried here on the east wind.’ Windbreaks erected to keep this wind at bay will protect a garden from caterpillars’. There just isn’t an answer to that.

Possibly the most widely followed remedies are the plant associations such as garlic amongst the roses. There are several of these and their devotees have almost maniacal faith in them. It would be quite wrong to write them off as useless but I have never heard of a single one that has worked for everybody and they must certainly be brought into operation before there is any sign of the problem. In other words, they may help to ward off an attack of a particular pest or disease but they will not get rid of one after it has struck.

Probably the most sensible explanation of all as regards these somewhat off-beat remedies is not that the pests are discouraged in some way but that their natural enemies are drawn into the area by the scent. This is much more feasible and would go a long way towards explaining why they sometimes work and sometimes don’t – when they don’t, it could simply be because there just aren’t any ‘goodies’ near enough to be attracted.

Although the more zealous and imaginative might flatter this whole plant association system with the title of biological control, a far more effective, and widely practised, method is to use the natural enemies of the pest, in a rather different way to that in which plant association might work. This has been done commercially for some years in glasshouses but the big snag is that this is the only place where it can be carried out with any chance of success.

The reason for this is obvious; you would have no control over the ‘goodies’ in the open air and most would simply disappear. Two that have been used widely under glass, both of which are available to amateurs, are the natural predator of the glasshouse red spider mite (Phytoseiulus) and a parasite of the glasshouse whitefly (Encarsia). Both are very effective at their job but the system as a whole has certain drawbacks, the main one being that it is difficult to control other pests by any chemical means without upsetting the goodies.

In the open garden, the nearest we can really get to this Utopian arrangement in which good always prevails over evil is to encourage the naturally occurring predators and parasites. Unfortunately, this has to be done in a rather negative way because the only method of attracting, for example, ladybirds, is to keep a thriving aphis population. Rather self-defeating. Really, the only thing we can do to encourage natural pest control is to avoid using sprays that will kill the predators and parasites.



12. March 2011 by admin
Categories: Garden Management, Pest Control | Tags: , | Comments Off on Garden Pests – Non-Chemical Control


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