Computers to fight grape bugs

Three years of research by 15 Hawkes Bay grapegrowers and wine companies has produced software to help interpret weather data when planning spray programmes.

The computer technology should transform how vineyards are managed, help lift crop quality and reduce environmental spray damage.

The system involves national or local forecasters supplying weather information to growers, who use the software to decide objectively when to spray against pests.

"The usual way of doing things has been to spray regularly, say once a fortnight, whether you need to or not," said project manager Campbell Agnew, of Hastings.

Sometimes growers spray up to 14 times a season, but now they can manage pests more intelligently.

"We can evaluate the use of spraying and target pests better," said Mr Agnew. "Some sprays control the natural predators rather than the pest, which is not what we want. A new wasp that targets the leafroller grub lays eggs in the grub and as the eggs hatch they eat the grub. We want to encourage that.

"And ladybirds are a natural predator of the mealybug, which live on vines then move to the bunch and excrete a honeydew on it. We want to protect ladybirds, not kill them."

Mr Agnew said the project would help growers achieve better-quality fruit, reduce spray costs and the impact on the environment, and let natural predators do their work.

"The new programmes were developed because winegrowers wanted data about how weather helped cause disease. We looked overseas for the data and the programmes were designed around that data."

- NZPA