Study from Vinschgau: South Tyrolean apples: pesticide contamination even in mountainous areas

Apples from South Tyrol are often found on supermarket shelves.

Study from Vinschgau: South Tyrolean apples: pesticide contamination even in mountainous areas

Apples from South Tyrol are often found on supermarket shelves. To ensure perfect-looking fruit, pesticides are used several times throughout the year - and they are now found widely not only in the region's growing areas, as a research team writes in the journal "Communications Earth

The Vinschgau in the west of South Tyrol is the largest contiguous apple growing area in Europe. Pesticides can be found throughout the valley up to higher altitudes, including in protected areas.

There are over 7,000 apple farmers in Vinschgau, Italy's northernmost province, who produce ten percent of all European apples, according to the study. Conventional cultivation there relies primarily on synthetic pesticides that are distributed using blowers to combat pests such as the codling moth and fungal diseases. This means that a high level of drift into the surrounding area is possible, especially in windy conditions.

Possible contamination of insects in nature reserves

The team led by environmental scientist Carsten Brühl from the Rhineland-Palatinate Technical University of Kaiserslautern-Landau (RPTU) examined eleven so-called elevation transects along the valley axis - stretches from the valley floor to the mountain peaks. Along these routes, samples were taken every 300 meters at elevations on four days in May 2022 - plant material and soil samples from a total of 53 locations.

"From an ecotoxicological point of view, the Vinschgau Valley is particularly interesting because the valley has highly intensive cultivation with a lot of pesticides and the mountains have sensitive alpine ecosystems, some of which are strictly protected," explained Brühl.

Previous studies have already shown in other regions that pesticides can spread significantly beyond agricultural areas and, for example, pollute insects in nature reserves. Contrary to what was previously generally assumed, the plant protection and pesticides in Vinschgau are not only found in the plants and the surrounding area, the scientists report.

The amounts of pesticides found decrease at higher altitudes and with distance from the apple orchards, but even in the upper Vinschgau where there is hardly any apple cultivation, several substances can still be detected in the soil and vegetation. "We found the funds in remote mountain valleys, on the peaks and in national parks. They have no place there," said Brühl. The reason for the widespread distribution is probably the sometimes strong valley winds and the thermals in Vinschgau.

Effects unclear

Even at the low concentrations measured, pesticides can lead to so-called sublethal, i.e. not directly fatal, effects on organisms, the researchers explain. For butterflies, a reduction in egg laying is conceivable. So far, however, it is largely unclear what effect chronic exposure to pesticides in low concentrations and mixtures of different pesticides have.

Such mixtures would not be taken into account in the environmental risk assessment as part of the approval process, but the substances would be considered individually. “This has nothing to do with the reality of the applications on the field or in the orchard and the fate in the environment,” says Brühl.

In total, the researchers detected 27 pesticides - 10 insecticides, 11 fungicides and 6 herbicides. "The concentrations we found were not high, but it has been proven that pesticides affect soil life even at very low concentrations," explained co-author Johann Zaller from the University of Natural Resources and Life Sciences in Vienna (BOKU).

Pesticide application technology needs improvement

The measurements were also carried out at the beginning of May, and additional resources were used over the course of the growing season until the harvest, according to the researchers. On average, dozens of applications of pesticides during the season are common in conventional cultivation - as a result, more complex mixtures of several substances and temporarily higher concentrations are likely.

According to the analysis, valley meadows near apple orchards were particularly contaminated, but pesticide residues were even found in remote mountain meadows at an altitude of more than 2,000 meters. One of the substances detected was the insecticide methoxyfenozide. It was found in almost half of the soil and plant samples, they said. In Germany, the use of methoxyfenozide has been banned since 2018 due to its environmental damage.

The team concludes from the results that the technology for applying pesticides in apple cultivation obviously needs to be improved. A drastic reduction in the use of pesticides is necessary. It is also important to promote so-called functional biodiversity in the apple orchards and their surroundings - for example with natural, flower-rich grassland in order to provide more living space for natural opponents of apple pests. However, consumers and supermarkets are also in demand, according to the researchers: More acceptance of apples that do not look quite as perfect is needed, as is often the case when fewer or no pesticides are used.