Shining a (UV) light on vineyard mildew control

New Zealand, the US and Europe are putting light-based tech to work against grape mildews, most notably powdery mildew, offering growers a way to cut fungicide use without compromising fruit. Early results are promising, and commercial trials are being scaled up.

In Marlborough, the Bragato Research Institute (BRI) is partnering with A Lighter Touch (ALT), to run a two-season UV-C trial on Sauvignon Blanc, from budburst to harvest, benchmarking against a standard spray programme. First-season observations report effective powdery mildew control, with robots delivering night-time UV to suppress fungal photorepair.

The most mature option is night-time UV-C passes (typically 100–200 J/m², once or twice weekly). Multi-year field work in Washington State and the Cornell programme show consistent suppression of powdery mildew when applied after dark, with no adverse effects on basic fruit chemistry at effective doses.

Europe is testing pulsed UV-C 'flash' systems (LIFEISLIGHT with Familia Torres/Jean Leon), aiming to cut energy and pass times while priming plant defences, while Australia is also piloting autonomous UV platforms in commercial blocks.

In all, UV-C is emerging as a spray-reduction tool rather than a total replacement, best integrated into Integrated Pest Management alongside canopy opening and targeted fungicides at times of high-pressure.