Native plants instead of herbicides a 'nirvana' vineyard solution

It's an awkward part of the vineyard to manage and one that is usually controlled with chemical sprays, but a Hastings vineyard is looking to nature in the battle against weeds under the vines.

"We are conducting a one-year pilot trial funded by MPI's Food & Fibre Futures Fund, to test the viability of native plants and cover-crop mixes in the area under vines, as an alternative to herbicides," Villa Maria research viticulturist Raquel Kallas said.

Te Awa vineyard trial is looking for plants that would suppress undesirable weeds, and not rob vines of nutrients or water. But it's complicated to measure.

"We are taking measures of vine vigour - how much the vine is growing, that includes shoot lengths and then pruning weights at the end of the season.

"We are also taking measurement of vine water status, as well as relative soil-moisture status, to see if the vines are competing with the plants for water.

"We'll also take biomass assessments, to see how many weeds come up in the trial, and last we'll take yield assessment and weigh the crop of each vine in the trial."

A wide variety of plants are being trialled: native species such as Carex comans (brown sedge), Leptinella squalida (Platts Black), Lobelia angulata, Muehlenbeckia axillaris and two varieties of Coprosma acerosa.

Cover-crop mixes include fescues, clovers, plantain, sheep's burnet and alyssum. But some plants are fussy about where they want to grow.

"In Hawke's Bay specifically - and then even within our vineyards - we have a lot of different soil types and different situations. So it is not a one-type-fits-all solution.

"A lot of people have had success with cover crops and vines in other areas of the world but we need to see and test what works for us here in Hawke's Bay."

Te Awa vineyard straddles the edge of the Gimblett Gravels, giving easy access to two soil types.

Villa Maria's regional viticulturist Jonathan Hamlet said if the trial is successful it would make his job a lot easier and the vineyard more sustainable, profitable and healthier, with better fruit.

"At the moment the alternatives to herbicides are under-vine cultivation and mowing, which creates extra workload, time pressures and expense," he said.

"So we are really looking at a kind of blue-sky picture.

"Having a cover crop under the vines that eliminates weed growth but won't compete with the vine is almost like the nirvana of a growing system, where we can actually do less to the vineyard but have better fruit quality and growing outcomes."

A challenge to the trial is that traditional cover-crops are popular with rabbits.

"As we've had an extremely-warm dry season this year, the rabbits are definitely more hungry and voracious than normal, so we have had to do some baiting for rabbits or they'd pretty much wipe out the cover crop."

So far the results have been promising, making it more likely the trial will be extended.

Data from spring and summer has shown no competition with the vines for water and unaffected vine growth.

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