Spring cleaning in vineyards: growers go after tiny mites

Mites go for the young, fresh, juicy green bits on the vines, destroying our next fine vintages before the grapes can even get started

GENEVA, SWITZERLAND – Mites are back, thanks to global warming, and that’s not good news for winelovers. Cheer on those growers out among the vines in coming weeks, as they go after the cheeky little pests who party in hordes and destroy young growth on vines.

The problem is that mites love dry, hot summers, and that’s what we’ve been having. Their enemies, acariens typhlodromes, don’t thrive in that kind of weather.

The ACW (Agroscope Changins-Wädenswil) federal research station says there is a solution. It’s complicated, however, because Mediterranean and other warmer climate pests are also arriving on the scene as temperatures rise, but using insecticides on them could spark a major population explosion of hungry mites.

The good news is that global warming is also bringing new predators of the pests into Switzerland, so researchers are scurrying to find organic rather than chemical solutions, a kind of bug eat bug approach.

Grape growers will have to be flexible enough to keep adapting and to use new spring treatments, says ACW. Its own research aims to find ways to simplify growers’ work in the vineyards, to encourage them to use these natural methods.

Pesticide use in the 50s and 60s in Switzerland, as elsewhere, killed mites’ predators and sparked a population explosion. Switzerland then became a pioneer in integrated production methods for growing wine grapes, an approach that in the past 30 years has dramatically rebalanced pests and their natural predators in Swiss vineyards. The second group has been given the upper hand.

A mite-free world requires continual fine-tuning, it now appears

This ladybug, hiding in a drywall in a Valais vineyard, goes after pests, but even an army of her friends won't be enough to ward off heat-loving mites.

The turnaround has been so dramatic that many younger growers have never seen a mite, according to ACW.

But now, says the federal agricultural research station, mites are on the march and heading for vineyards again, particularly in canton Valais.

Integrated production is the next best thing to organic, known as bio in Switzerland, with its emphasis on ecological balance but without some of the constraints imposed by organic growing regulations.

One organic rule in particular, about not growing grapes too close to vine parcels where pesticides and herbicides are used,  makes it difficult for many Swiss growers to go this route, since they have small parcels in the midst of several others owned by a number of growers.

Swiss growers’ integrated production charter  puts the accent on using organic methods as much as possible; creating a growing environment that encourages bio-diversity; soil preservation over the long term and minimal impact on water, soil and air; protecting the health of vineyard workers while producing top-quality, healthy grapes.

It has been nearly unanimously adopted in Switzerland, with excellent results. A group of Australian researchers studying Switzerland’s use of IP in vineyards in 2007 noted that “adoption by the Swiss wine industry of the Integrated Production (IP) approach to wine grape growing has shown a large increase in biodiversity and a reduction in pesticide and … fertilizer use.”

It turns out that there isn’t one simple solution to maintain this admirable situation, which has also helped growers develop good quality wines, but rather a process of continual fine-tuning in the vineyard.