"High wire is a good concept and will be the way to grow in future," technical consultant Derek Hargreaves told the CGA conference. "But don't try it for next year unless you are certain it will be a great summer." Hargreaves said that the high-wire crop in the project - undertaken in two near-identical commercial glasshouse blocks - had achieved almost 20 sticks per square metre more than the conventional cordon crop at one point, and quality was better. "But the extra income was never enough to cover the extra costs," he said.
Much of the additional labour cost was associated with crop training - despite use of the Qlipper system, which Hargreaves described as the best currently available - and de-leafing.
The project had shown that it is difficult to keep a high-wire crop in balance without supplementary lights, he said. "Crop vigour was either too strong or not strong enough. We looked at four varieties and all were found wanting - we need breeders to come up with varieties suited to the system."