The agronomy diary

Winemakers perspective on vineyard agronomy

As the New Year approaches, this month Hutchinsons agronomist Rob Saunders sits down with head winemaker at Defined Wines, Nick Lane, to get a winemaker’s take on the management practices that will drive wine quality in the season ahead

Being engaged in the whole winemaking process from vine to bottle and understanding the subtle impacts agronomy practices have on wine quality is fundamental to successful businesses, according to Nick Lane.

From a winemaking perspective, he said that in our marginal climate, he saw a strong correlation between quantity and quality, so growers and winemakers should agree targets on ripeness, disease and quantity early on, allowing crops to be managed to meet these goals.

“Climate and getting crops ripe is the most challenging factor in the UK. Growers often run into trouble with big crops delaying ripeness and compromising maturity. If a large crop is expected, the associated risks must be managed,” he added.

“Bigger crops generally require more time to ripen, so are harvested later, which implies lower temperatures at the end of ripening and greater disease risk, notably from Botrytis.

“You are far more likely to suffer the ravages of Botrytis harvesting in late October than the beginning, purely because grapes are on the vine for three to four weeks longer.”

Tight-bunch Pinot varieties are at particular risk due to the propensity for berries in the centre of the bunch to burst and start rotting. He agreed with Rob Saunders’s suggestion that products like Regalis (prohexadione) may help mitigate risk by improving skin robustness and reducing the number of berries set.

Knowing when to pick

Deciding when to pick crops is probably the single biggest decision to make, so Nick said: “Accurately assessing maturity and quality is key.

“It’s really a winemaking decision because there is a strong correlation between when you pick, the kind of wine produced, and how good it is.”

He encouraged growers to have their own refractometer kit for measuring sugar (Brix) levels, or at the very least, send samples from every block to the winemaker before picking.

“I prefer bunch sampling, but you have to press every berry. Sample at least two rows from every block, sampling from every side, and at least a dozen bunches for every sample,” said Nick.

Acid evaluations are more tricky to do on-farm, but measuring disease, notably Botrytis infection, with visual assessments provides valuable information. Laboratory analysis of gluconic acid of a grape sample will provide a more measurable indicator of fruit degradation and the ramifications for winemaking.

Useful management practices

Good canopy management throughout the season, supported by appropriate leaf thinning where required was very important for ensuring ripening, said Nick.

Good disease management and plant nutrition is also fundamental, both for growing healthy, productive canopies with good yield potential, and for ensuring sufficient yeast-available nitrogen for fermentation.

Nick recognised in-season tissue sampling can help highlight potential issues in time for nutritional programmes to be adjusted, and believed this was where there could be greater collaboration between growers and winemakers.

On sites with potential nutritional issues, Rob recommended leaf petiole analysis at early flowering to help optimise plant nutrition and manage the canopy, followed by leaf blade sampling at veraison, the results from which would help fine-tune plant nutrition and influence juice parameters, such as yeast-available nitrogen and potassium. Working together

As a contract-only winery, Defined Wines is keen to work with growers to ensure vine agronomy produces the best quality wine possible.

As part of this, it runs regular client webinars throughout the season, featuring talks by Rob Saunders and industry expert Peter Hayes. They also hold an annual trade tasting event to build links further along the supply chain.

“We want growers to get engaged in the whole winemaking process to create successful businesses and good quality wines,” said Nick.

He believed environmental sustainability was becoming increasingly important for wine producers and said the most tangible impact was the development of hybrid disease resistant varieties.

While hybrids offered exciting prospects for disease resistance, he acknowledged it was early days, and time would tell how they fared in terms of wine quality.

“Hybrid grape varieties perhaps look a little more promising for still wines, whereas for sparkling wines it’s slightly more challenging as I’ve not yet seen any hybrids that can challenge traditional champagne varieties.”

In conclusion Nick said: “To increase the chances of producing the best wine and selling it for as much as possible, there are two kinds of grapes we like; ripe and clean, clean and ripe.

“The best thing for a crop is the shadow of the grower. It’s about being interested enough to spot issues early and take steps to rectify them.”