Speaking to news agency ATS, Gilles Cornut of the Vaud federation of winegrowers said that the abundance of Suzukii flies throughout Switzerland at the end of August gave vineyard owners “cold sweats” and resulted in grape losses of two to four percent.
The damage is limited, however, due to the cold nights during September which killed off some of the flies.
Vaud winegrowers – whose harvests start in earnest this week – are also using a biological substance containing kaoline to fight the bug, which Cornut stressed would have no impact on the quality of the grape.
The presence of the fly significantly increases the workload for winegrowers, who must react quickly to harvest or treat unaffected grapes.
“We’ve had a real invasion,” commented Markus Leumann, head of a Swiss-German working group tackling the problem, to ATS.
Winegrowers in ten Swiss-German cantons have, for the first time, resorted to insecticides to combat the fly, the only method considered effective enough.
Nevertheless Switzerland can expect a good harvest this year following an autumn of warm, sunny weather, said Cornut.
The last three weeks of September were decisive, with hot days and cold nights helping to develop flavour in the grapes.
Conditions in June, when the vines were starting to bud, were also ideal.
This year’s positive news will be a relief to wine fans, after last year’s bad weather resulted in the worst harvest since 1980.
Just under 84 million litres of wine were produced in Switzerland in 2013, a 16.5 percent decrease on 2012.
Most of Switzerland’s wine is produced in the cantons of Geneva, Valais, Vaud, Neuchâtel and Ticino, with a minority of vineyards in Swiss-German cantons.
Swiss wine is mostly consumed domestically, with only around one percent exported.