Promising trial to slash
herbicide use

A project investigating precision weeding in vineyards could prevent thousands of litres of herbicide use – and save thousands of cubic metres of water – across New Zealand’s viticulture and horticulture industries.

Six New Zealand vineyards have partnered with Lincoln Agritech and the Ministry for Primary Industries’ (MPI’s) Sustainable Food and Fibre Futures (SFF Futures) fund to trial high-pressure water weeding (also known as waterjet weeding).

Mark Eder, Manager of Waiata Vineyards in Waipara, North Canterbury, heard about high-pressure water weeding, or waterjet weeding, several years ago, before seeing it in action in Italy in 2018.

He realised it could drastically reduce Waiata’s herbicide use. Not only does this fit with the vineyard’s ethos of sustainability, but it’s becoming increasingly important in a world demanding less pesticide use.

In April 2022 Waiata Vineyard joined forces with Cloudy Bay, Pernod Ricard, Indevin, Villa Maria, and Yealands vineyards, all in Marlborough, to import a second-hand Caffini Grasskiller from Australia and work with Lincoln Agritech to rationalise the water use.

Smart sensing device

The aim of the two-year project is to develop a smart sensing device and valve that integrate with the waterjet weeder so it activates only when it senses a weed – and turns off when it doesn’t.

“The original machine uses about 1000-1500 litres per hectare,” says Lincoln Agritech Agronomist Allister Holmes. “We intend to reduce this to less than 500 l/ha. That’s actually less than the typical amount of water used when spraying herbicide, which is between 600 and 900 l/ha.”

The first trials in North Canterbury and Marlborough are evaluating the Caffini Grasskiller against the standard practice of multiple herbicide applications per season.

“We’ve found that it’s best to use it on an under-row area that doesn’t have large, perennial weeds such as docks and mallows present, as it doesn’t totally kill these weeds,” says Allister.

Optical sensors

For the next trial, the team has fitted optical sensors to the weed control heads that can distinguish between green and brown, so the weeder can turn water on and off, depending on whether it senses weeds.

“We expect this technology will allow water use to be reduced by 75%,” says Allister.

Between them, the six vineyards in the trials cover nearly 5000 ha. If the technology works as expected, it will take more than 50,000 litres of herbicide a year out of their weed management programmes.

However, it could do even more. There are 40,000 ha of grapes grown in New Zealand and around 68,000 ha of perennial tree crops, which could also benefit from the technology, grown nationally.

“If just another 10% of the perennial tree crops in New Zealand took up this technology, and replaced herbicides at the same rate, there would be an additional 60,000 litres less agrichemicals used every year,” says Allister.