Sounds of battlefield over the orchard

Press, 5 December 1985, Page 71

Sounds of battlefield over the orchard

PA Nelson Neighbours of Geoff Etherington, near Nelson, could be forgiven for thinking he has turned the normally peaceful neighbourhood into a battlefield.

Mr Etherington is a pipfruit and kiwifruit orchardist at Brightwater. Recently he has been testing an anti-hail device that sets off a series of explosions aimed at disturbing the formation of the ice molecules that produce hail. The shock waves are effective at an altitude of 8000 m to 10,000 m, where hail forms. The machine was imported from France for about $50,000 and is the first in New Zealand.

Mr Etherington began looking at the possibility of protecting his crops against nail damage after three bad seasons in the last four years.

Last year hail wiped out his export- crops. It was impossible to put a cost on the damage, but he believes that if he had installed the anti-hail device last year it would have paid for itself in one season.

Mr Etherington learned about anti-hail develop-

ments overseas and decided to travel to South Africa and Europe to see the results.

On his return he reported on discussions with foreign fruitgrowers for the Fruitgrowers’ Federation, which began investigating the prospect of importing the equipment. Mr Etherington’s device arrived from France recently and is now working.

Because the cannon will assist nearby fruitgrowers, neighbours pitched in to prepare the site and building for its installation.

Control tests in Switzerland and France suggest the device is 100 per cent effective within 500 m of the site, protecting about 78ha of crops. ' It can be set off and stopped by remote radio control carried by the orchardist. Once triggered, the cannon sets off explosions every six seconds. A charge of acetylene gas flows into a chamber where it is ignited. The funnelshaped barrel sends up shock waves or a miniatomic bombardment of ions, disturbing the formation of the ice molecules.

If other growers in the

area follow Mr Etherington’s lead, a central meteorological radar system could be installed to track storms and automatically operate anti-hail devices, says the Fruitfed market development manager, Mr Mike Wade.

The machine is likely to be needed for limited periods each season, possibly half an hour or an hour once or twice a year. Waimea County Council health inspectors measured sound levels at various points round the district.

The health inspector, Mr David Lewis, said the explosions were “very loud,” particularly at the source. However, potential noise nuisance was minimal because it would; be used for only brief periods once or twice a year.

Although noise levels do not conform with county standards, Mr Lewis doubted whether action would be taken against its use.

Noise levels reached 100 decibles at source, 60 decibles 300 m from the site, and 45 decibel in Brightwater, where background noise levels were higher.