Beyond ‘Spray and Pray’: Breaking the Viticulture Addiction

Grey skies over the vineyard reflect grower uncertainty.

As I sit at my desk on yet another unseasonably wet day in Martinborough, the grey skies reflect my mood. Grapes on the vines are ripening, and the nets have already been on for a fortnight. Two days ago, it was unusually humid, and the night that followed was unusually warm. That combination—heat, humidity, and fruit so close to harvest—was enough to interrupt my sleep, and I suspect more than a few local growers were lying awake as well. At this stage of the season, fungal disease pressure isn’t just a technical concern; it’s a knot in the stomach.

Powdery mildew infection on a grape bunch - a common and aggressive fungal disease in vineyards world-wide

Powdery mildew, downy mildew, botrytis—these fungal diseases have always been part of the background noise of viticulture. But in recent years they’ve begun to feel more like the main storyline. And even though 98 percent of New Zealand vineyards are certified sustainable, our approach to protecting vines remains remarkably consistent across organic, biodynamic, conventional, regenerative, and “sustainable” growers alike: we spray.

And it’s worth stating plainly: growers, certainly in our region aren’t clinging to this system out of complacency. They’re fully aware of the risks and genuinely ready to adopt better tools — but many of the most promising innovations, CRISPR‑accelerated breeding among them, simply aren’t available in practical form yet.

A recent article on Newsroom by Nikolai Simes captured this contradiction with uncomfortable clarity. Whether a grower identifies as organic or conventional, the underlying challenge is the same: in a climate like ours, both systems still rely on frequent fungicide applications—typically every 7–14 days through the growing season—to keep mildew at bay. Organic growers are often the most committed to reducing inputs, but even they are caught in the same weather‑driven cycle.

One grower in the research put it bluntly: “Organics is killing too.” This should be read less as a criticism of organic principles, more an acknowledgement of the reality: when disease pressure is extreme, even organic sprays can contribute to what Simes calls a microbial vacuum—a vineyard environment where the beneficial microbes are knocked back along with the harmful ones.

We now understand how much human health depends on microbial diversity; vineyards are no different. When we repeatedly wipe out the good with the bad, we risk creating the perfect conditions for the most aggressive fungi to flourish. It becomes a vicious cycle: more spraying leads to more resistance, which leads to more spraying. Add climate volatility—warmer nights, humid mornings, sudden rain events—and the pressure intensifies.

“State of the art” three row vineyard sprayer

The article also pointed to the economic forces that quietly shape our biology. New Zealand’s growth in low‑value bulk wine exports encourages high yields. High yields mean thicker canopies, more moisture retention, and greater disease risk. That, in turn, demands more fungicides. It’s a loop where bad economics reinforce bad biology, locking growers into a system that becomes harder to escape each year.

And yet, for all the anxiety that nights like this bring, the story isn’t one of despair. Quietly, steadily, growers and researchers around the world are experimenting with new ways of thinking — and some of the most compelling examples are coming from places facing even tougher conditions than ours.

A New Example From France: Essential Oils Instead of Copper

In a recent Decanter article, Matt Walls profiled Château l’Ermite d’Auzan in the southern Rhône — a region where increasingly unpredictable weather is making organic farming harder every year. To make matters worse, France’s National Agency for Food, Environment and Occupational Health & Safety has recently restricted the use of most copper fungicides, the main organic defence against downy mildew. Many growers are wondering how they can continue to farm organically at all.

But at l’Ermite d’Auzan, fourth‑generation grower Tanguy Castillon has taken a radically different path: he has replaced copper entirely with essential oils.

Not in a trial block. Not on a few hectares. Across the whole estate.

And he makes the oils himself.

Along the long driveway to the winery are neat rows of 15 different aromatic plants — thyme, rosemary, lavender, oregano, mint, curry plant. Each contains different active compounds, and Tanguy uses five different types over the course of a season to prevent the mildew from developing resistance. After harvesting and drying the herbs, he distils them in a simple alembic still: steam passes through the plant material, carrying volatile compounds that separate as the steam cools.

Finding the right concentrations took time and a lot of trial and error. Oregano oil requires only 80–100 ml per hectare; lavender needs nearly three times that. And because oil and water don’t mix, he discovered that blending the oils into milk first created a stable emulsion for spraying. The treatment is curative rather than preventative, and it must be reapplied after rain — but it works.

The 2024 vintage was a brutal test. Spring rains triggered widespread downy mildew across the Rhône, with some neighbouring estates losing entire vineyards. L’Ermite d’Auzan, however, suffered almost no mildew and saw no drop in production. The family attributes this entirely to the essential‑oil sprays.

And the benefits go beyond disease control.
Since abandoning copper:

• Soil pH has dropped from 8.3 to 7.7 — a healthier range for microbial life
• Organic matter has risen from 1.8% to 2.5%
• The gap between sugar and tannin ripeness has narrowed, leading to lower alcohol wines

There is a cost: Tanguy now sprays 15–17 times per year, compared with 13 previously. But the results have convinced even his initially sceptical father. “I’m a student again,” Jérôme says, “and my son is the teacher.”

Growers from Lebanon to Greece have visited to learn from him. Tanguy shares everything freely — he isn’t selling a product, just knowledge. And he’s now working with INRAE, France’s leading agricultural research institute, to refine and expand the approach.

If he’s right, this could mark a turning point for organic viticulture — and not a moment too soon.

Is Science Catching Up?

Alongside these ecological approaches, scientific innovation is accelerating.

Growers are getting smarter about canopy management—opening up airflow, reducing humidity pockets, using trellising and leaf removal more strategically, and even bunch thinning to reduce crowding. These practices are already widely used in Martinborough and unquestionably make a big difference. But on their own, they are not enough.

Careful leaf picking and bunch thinning has helped to present these ripe Abel clone Pinot Noir grapes in perfect condition

Weather‑based decision tools now predict infection events with surprising accuracy, and spore traps and sensors can warn growers before symptoms appear. The Research Supplement of the last 2025 NZ Winegrowers magazine lists “Rapid early detection of powdery mildew using VOCs to enable better control solutions” and Rapid detection of fungicide resistance in grapevine powdery mildew in New Zealand” as current research projects. These tools help with timing and can prevent catastrophic misses, but they don’t change the underlying reality: we’re still locked into the same spray‑based system. They make the treadmill more efficient, but they don’t get us off it.

Perhaps more promising are the advances in the breeding labs. Researchers are exploring wild North American grape species like Muscadinia rotundifolia, which carry natural resistance genes. Teams at CSIRO, INRAE, Geisenheim, and others have successfully transferred these genes into vinifera varieties, creating next‑generation hybrids (PIWIs) that can reduce fungicide use by 70–90% while still producing recognisably vinifera‑style wines. I’ve previously touched on the use of PIWIS in earlier blogs Dipping Into PIWI Wines and An Introduction to the Wines of Vancouvers Island’s Cowichan Valley.

However, many growers I’ve spoken to remain firmly wedded to traditional vinifera varieties and are sceptical—sometimes openly dismissive—of PIWIs and other disease‑resistant hybrids. The assumption is that they can’t make wines of true quality, or at least not wines that express the delicacy and precision we associate with this region.

But perhaps it’s time to look again.

The advances being made in Europe, Australia, and the US are not fringe experiments anymore. The newest PIWIs are high‑vinifera crosses with flavour profiles far closer to classic varieties than many realise. And if they can reduce fungicide use by 70–90%, they deserve more than a reflexive dismissal. In a future defined by climate volatility and rising disease pressure, keeping an open mind may be one of the most important tools we have.

And then there’s CRISPR.
Gene editing isn’t in commercial vineyards yet, but the research is moving fast—editing the vine’s own susceptibility genes to block pathogen entry. It’s precise, elegant, and potentially transformative.

Where We Go From Here

The challenges we face—climate change, biodiversity loss, antimicrobial resistance—won’t be solved by incremental tweaks or slightly “greener” sprays. They require a deeper rethinking of how we farm, how we value wine, and how we understand the vineyard as a living system.

The future of mildew management won’t hinge on a single breakthrough. It will be a mosaic:

• Resistant varieties that drastically reduce the need for spraying
• Precision tools that guide intervention only when necessary
• Microbiome‑positive viticulture that builds resilience from the ground up
• Ecological and probiotic approaches that enhance life rather than eliminate it
• Business models that reward quality, place, and long‑term thinking

Perhaps this is where wine can lead agriculture rather than follow. After all, wine is one of the few agricultural products where place is still central to value — where soils, microbes, climate, and human judgement are celebrated rather than engineered away. If any sector can show what it looks like to farm with ecological intelligence, to work with living systems rather than against them, it should be ours.