3 August 2001

Organic spud grower sings praises of dropleg sprayer

By Wendy Owen North-east correspondent

DROPLEG sprayers have long had their enthusiasts among conventional growers, but now an organic farmer has given the novel system the thumbs up.

Stephen Metcalfe, who has a partially organic unit at Boroughbridge, York, paid £4000 for a hydraulic DADS system last year.

Although last season was exceptionally wet, he is convinced the new system helped keep potato blight at bay at Low House Farm until late August/early September.

"Its a very simple idea but it works better than conventional methods because the legs hang down under the rows and spray a mist of copper upwards under the leaf, where blight often takes hold," says Mr Metcalfe.

"Its difficult to say categorically whether I achieved better blight control using the DADS because it was not a normal season. But when you look at a newly-sprayed crop you can see the droplets clinging to the underside of the plant.

"I cant hope to control blight completely; I dont think thats possible in organic potatoes. The copper is used to hold it off until as late in the season as possible." Once the crop succumbs to the disease, it is burned off using propane gas.

Mr Metcalfe has not changed his 1kg/ha rate of copper because the system employs more nozzles, so it is important to keep the spray pressure high. Water volume is 400 litres/ha instead of the 300 litres/ha used before.

"I cannot reduce spray rates because more of the plant is being covered, although the spray mist does tend to be finer."

The system is fitted to a Chaviot sprayer with 24m boom and 3000 litre tank, to which 1 litre/ha of cotton oil is added as an adjuvant.

The droplegs can be folded with the boom for road transport and the Superjet nozzles do not block as easily as those on conventional spray systems, says Mr Metcalfe.

Manufacturer Benest is so convinced of the techniques efficacy that it is allowing farmers to pay 50% at the beginning of the season and the rest at the end of the year, if the grower is satisfied. &#42


&#8226 Gives spray coverage under leaf canopy.

&#8226 Available in hydraulic and air-assisted forms.

&#8226 Can be fitted to most modern sprayers.

&#8226 Spray applied at 400 litres/ha containing 1kg/ha of copper.

&#8226 Cotton oil used at 1 litre/ha as an adjuvant.