12 January 1996

Wiping the floor with em

By Andrew Blake

A HANTS contractors experience with a novel weed-wiper last summer involved much "trial and error", and resulted in several modifications.

When Allman launched the Eco-Wipe at last years Smithfield Show, Stockbridge-based Luke McCall saw a chance to offer a specialist service, controlling weeds in areas conventional equipment could not reach or where overall spraying was inappropriate.

After treating more than 800ha (2000 acres), he claims to have had few complaints, but has been on "quite a steep learning curve".

The machine, based on a bank of independently mounted tubular carpet wicks, is intended to "float" over uneven ground. Originally designed by staff at the Royal Agricultural College, its contour-hugging ability was aimed especially at environmentally sensitive rough grassland.

May to September

Much of Mr McCalls work from May to September was for English Nature, the National Trust, Hants Wildlife Trust and even the Ministry of Defence. But about half was on commercial farmland. "Ive done a lot on the old, uneven flood plain pastures of dairy farms around here."

Like similar machines, the Eco-Wipe relies on the height difference between weeds and crop, in this case grass. Mr McCalls main targets were nettles, docks, thistles and some sterile brome."One of the good things about the machine is that you can adjust the pressure," he says. This allows output to be matched to weed density. But a calibration chart from the manufacturers was "of limited use".

Dilution rate is still something of a "grey area", he claims. "For Broadshot the recommendation is a 4:1 chemical to water ratio. But I ran at 10:1 – thats still quite concentrated." Using too strong a mix risks scorching and inadequate translocation of the chemical, he reasons.

"Operation is mostly down to practical experience. Its a job you cant rush." Travelling too fast in dense nettle patches soon exhausts the wicks, he explains. On average he reckons to cover "40-50 acres a day" with his 4.3m (14ft) wide machine.

Thistles and nettles

"Thistles werent easy this year because they didnt grow very well in the drought." Nettles, too, proved tricky. What worked well one day gave much poorer results in apparently identical conditions the next. But on average he reckons he achieved "95-98% kill". "You cant expect to get rid of them completely in one year."

With much of the work on very dry, uneven land, wear and tear on the machine took its toll. But the makerss response has been "brilliant", says Mr McCall.

"Altogether its had about nine modifications." The original boom skids soon wore through. Several other points needed "beefing up", and chemical corrosion required changes to the electric pump diaphragm. Pneumatic instead of solid tyres would be a useful option to ease road transport, he says.

"At the moment there is no way of decontaminating the wicks," he adds. Ideally this means carrying two sets for different chemicals.

&#8226 Generally good weed kill despite dry conditions.

&#8226 Optimum herbicide concentrations still under investigation.

&#8226 Considerable mechanical strengthening required.

Changing the wicks on the Eco-Wipe is straight

forward, but making use of the herbicide drained from them after use is tricky, says Mr McCall.