Be nasty to them!

Press, 7 August 1981, Page 13

Be nasty to them!

By

JUDSON BENNETT

Features International

How to get rid of weeds . . .

What can you do about those rampaging weeds which threaten to swamp your flowers and vegetables without trace? . Of course, you can spend back-breaking hours pulling them up. Or you can swamp the garden with expensive chemicals. Or you can simply stamp angrily down the garden and tell those w’eeds that they are simply not wanted and will they kindly go away! Frightening weeds out of your garden is seriously being put forward as the answer to every. lazy gardener's prayer by Dr Jack Tierney, of the Burbank Plant Institute. Los Angeles.

“We have found, after intensive research, that some people actually do have a built-in weed-killer," he says. “They emanate feelings of hostility so fiercely • that weeds just- won’t pop up when they are near.

“It sounds far-fetched but it actually happens. During one experiment, a woman shouted every morning at a crop of thistles at the bottom of her garden. Within a month they were all dead — but thistles in adjoining gardens were flourishing as heallhilv as ever."

Similar experiments at the University of Zurich have convinced a botanist. Dr Walter Haast. that weeds can be hurt and worried in the same way as animals and humans.

By connecting up weeds with a special version of a skin galvanometer — an instrument which detects emotional responses in humans — he claims to have discovered that weeds do respond to hostile reactions, loud noises, and the threat of destruction.

“Our readings show that in some way, a plant can ‘think’ and worry about its chances of survival,” he says.

Now Dr Tierney and his team are investigating other ways of putting the frighteners on weeds, mainly by scaring them with highfrequency sound waves

This research trend began two years ago in France where scientists found they could destroy unwanted weeds by beaming them controlled doses of high-fre-quency sound. Dr Tierney and his team claim to have devised a neat, hand-held generator that produces sound that weeds hale — and speedily banishes them from a garden.

Another alternative, being developed by teams of Australian engineers and scientists at Deakin University. Victoria, kills weeds with microwaves. They plan a small robot which will crawl around the fields or gardens obeying orders fed into the magnetic tape that controls it and dosing the ground with microwave radiation which destroys weeds without harming plants or grass. Target for immediate extermination by this method is the dandelion, but the problem is to get the dose just right, leaving nearby plants undamaged. It is hoped that eventually a commercial version will be on the market, making all the present weed-killers obsolete. A recent international crop

protection conference in California. was told that by far the best way to get rid of weeds is by electrocution. Here again, it will be some time before a suitable domestic model appears in our garden sheds. At present, there is an experimental radio-con-trolled device which creeps around flower or vegetable patches delivering a lethal dose of electricity to the weeds.

Weeds, it has been found, are less able to cope with doses of electricity — 3500 volts and upwards — than flowers and vegetables.

Ideally, weed eradication works best on a large scale where a powered electrical device rolls over the bare earth some time before the land is planted. The main commercial research concerns the eradication of tangling, grass-like weeds that stifle potato and sugar-beet crops. It has been found that electrification of the land removes many of the destructive growths that tend to choke and kill young shoots at vital stages in their development. The latest electrocution devices can even

distinguish between certain weeds, and crops and flowers under cultivation.

Nature, too. is. helping in the fight against weeds. Scientists in Japan, curious about certain areas of land that appeared to be weedfree, have found after intensive soil analysis that certain types of worms and soil creatures give off bodily substances that hinder weed growth. Not all the experts want weeds to disappear completely. A leading British agriculturist. Dr Lancaster Dobson, says there is a credit side to many weeds that is not acknowledged: they give the soil a chemical balance which it would be foolish to disrupt.

Some weeds, he claims, provide ground cover and moisture for certain plants What has pleased, and surprised, botanists is the fact that worms, insects, and birds apparently are unaffected by the most spectacular weed destruction programmes.

This means, says Dr Tierney. that however nasty you are to weeds — bombarding them with hidden rays, or giving them the rough edge of your longue —the birds and the bees could not care less.-