They are not extinct and continue to plague the winegrowers: first and foremost the cherry vinegar fly, which is once again on the advance – not welcome in the vineyards. And when vintners defend themselves against pests, when they spray, it has a „G’schmäckle,“ as the Swabian trivialization of the term taste so aptly suggests, even so in neighboring Württemberg. Here, on a walk through the vineyards in Wartberg, a top Heilbronn site, individual parcels are easily recognizable by their white „whitewashed“ rows of vines.
GERMANY (Heilbronn) – „The hikers who pass through here may wonder what this is all about, and whether this might make itself felt later in the glass in terms of taste,“ states Martin Heinrich of the G.A. Heinrich winery, located at the foot of the Wartberg. „But it’s all good, it’s a colleague’s attempt to keep the pests away from the grapes.“ The city marketing in Heilbronn is rather unhappy about this phenomenon, because apart from wine professionals hardly anyone can know what was put on there and thus such incidents could scare away the one or other guest who wanders here and lets the beautiful view over Heilbronn wander into the distance. The remarkable and praiseworthy efforts around the city vineyards could thus be counteracted, so the not unfounded fear.
Statement from Markus Drautz
“The plots that are so visible by their white appearance belong to us,“ Markus Drautz says when asked. „It is our approach to do something against the cherry vinegar fly. This involves kaolin, i.e. white clay mineral, which we have applied to our vineyards here,“ explains the winemaker. „This is new territory for us and we think it’s worth a try. We still have to refine the application technically, but for the time being we are satisfied, although you can only know exactly afterwards. Anyway, we feel good about not having to use insecticides instead.“
The kaolin that Drautz-Able applied in the Wartberg comes from Switzerland. There, the manufacturer Stähler Suisse SA developed the agent called „Surround,“ which is supposed to help against pests in orchards and vineyards, and brought it to market maturity. Briefly summarized, the application against the cherry vinegar fly (KEF) in viticulture states on the part of the manufacturer: „Surround forms a kaolin layer over the grapes, which hinders the KEF females in laying their eggs. In addition, the white coating has a confusing effect on the KEF.“
For winemakers and wine customers alike, it is important to know that kaolin is toxicologically harmless, inert (i.e., does not participate in chemical processes), and has no negative effect on the vinification of the treated grapes or on the quality of the wine. Kaolin consists of natural clay and forms a physical barrier against various pests. In addition, kaolin dries moisture from the plants faster, reducing diseases. Finally, a layer of kaolin also acts against solar radiation, preventing sunburn of the grapes, which has become common in recent years.
Blueprint for the Heilbronn Wingerter?
Kaolin must not be confused with lime, although to the layman it looks as if the vineyards were limed. In the fight against the cherry vinegar fly, there have already been experiments with lime, but it affects the PH of the grape juice in the tank, and so these experiments were quickly abandoned. Kaolin, on the other hand, as studies in Switzerland have shown, has no effect on grape juice and can be applied several times and even just before harvest. „There is confidence in the agent,“ say the winemakers who have successfully applied kaolin so far. First and foremost are Fellbach producers such as Weingut Aldinger, which even treats its own Lemberger plants with kaolin, although this variety is rather unsusceptible to pests compared to Trollinger or Dornfelder. In the course of the application with kaolin, the local winegrowers point out the harmless application with information distributed in the Fellbacher Kapellenberg and hope that people will not speak disparagingly of „spraying“ or of „spoiled“ grapes.
Natural operating agent for winegrowers
So, no excitement about the white „whitewashed“ vineyards. The kaolin applied in this way was formed millions of years ago during the weathering of feldspar. Kaolin is mined mainly in Brazil, the USA, the UK, Germany and the Czech Republic. Worldwide, approx. 28 million tons of kaolin are produced per year. The clay mineral is used, among other things, in Meissen porcelain, as a white pigment for paints, as a filler and colorant for paper production, in cosmetics, in medicine (including remedies for heartburn) and is also a carrier material in the food industry and ultimately also in pesticides. The organically working vintner or gardener thus obviously has an operating agent that can contribute against persistent pest pressure and against wetness after heavy rainfall.