Research

The Green Deal of the EU includes two essential objectives: the reduction of pesticide applications and the conservation and restoration of biodiversity. Pesticide reductions are expected to increase the diversity and abundance of natural enemies of pests and consequently also their biocontrol success. However, the vast majority of natural enemies are arthropods, and their diversity strongly declined in the last decades at a global scale. Among other stressors, climate warming is a major driver responsible for the decline of arthropods. In agroecosystems, arthropods are also confronted with a second stressor: agricultural intensification, defined as the increase of agricultural productivity per unit area. Although these two factors are known to be tightly linked, they are usually analyzed separately. However, they may interact additively or synergistically boosting the negative consequences on arthropod diversity in agroecosystems. Apple is the most dominant fruit species in Austria. A serious pest mite, the red spider mite Panonychus ulmi, was efficiently controlled by predatory mites as natural enemies in the past, but regained nowadays the status of a main pest in Styrian apple orchards. Our main hypotheses for this project are: (i) climate warming reduces mite diversity; (ii) synergistic effects between climate warming and agricultural intensification (e.g. pesticide applications) enhance the negative effects on mite diversity; and finally (iii) the natural enemies (i.e. predatory mites) suffer more from the two stressors compared to their prey (i.e. pest mites), which lead to insufficient biocontrol of pest mites. First, we will sample mites in integrated, organic orchards and extensively managed apple meadow orchards (i.e. no pesticide and fertilizer applications) in Styria during two growing seasons, which allow the evaluation of climate warming and agricultural intensification effects on mite diversity. Additionally, mite diversity in extensively managed meadow orchards will be compared between 1985 (historical mite data are available) and 2024/25, to evaluate only climate warming effects on mite diversity. Second, climate warming may indirectly influence mite diversity via promoting agricultural intensification. For example, the use of fungicides in apple orchards increased because of apple scab incidences in the last two decades in Austria, and predatory mites are known to be highly sensitive to fungicides. Thus, micro-climatic data from apple orchards (1961-2025) will be integrated in a dynamic forecast model for apple scab to evaluate, whether climate warming effects could be a potential driver for higher incidences of apple scab indicating synergistic effects between climate warming and agricultural intensification on mite diversity.

Grape powdery mildew, caused by Erysiphe necator Schwein., is one of the major diseases in viticulture. Currently, the pathogen is mostly controlled with 6-10 fungicide applications. Due to the negative effects of pesticides on the ecosystem, the EU Commission aims to reduce the pesticide use by 50 percent by 2030. This project contributes to this goal and aims to reduce the number of fungicide applications needed to control powdery mildew without sacrificing crop quality. There is evidence that especially at the beginning of the vegetation there is a possibility to reduce the number of fungicide treatments. Mathematical models can make an important contribution here; however, in order to fully exploit this potential, numerous gaps in knowledge about the epidemiology of the pathogen still need to be filled. Targeted and thus pesticide-reducing management requires consideration of local disease development. The project addresses key factors here: The time of primary infection, the spread of ascospores and the incubation period will be investigated in combination with weather factors under natural and controlled conditions. Based on these results, mathematical models and regionally adapted fungicide strategies for winegrowers will be developed. These knowledge-based strategies will enable sustainable concepts for plant protection in viticulture and contribute to the achievement of a 50% pesticide reduction.

As a result of increasingly strict legislation on the use of pesticides, especially glyphosate, and pressure from society, alternative methods of weed control in permanent crops such as orchards and vineyards are gaining in importance. In a transnational cooperation, alternatives in weed management are therefore to be developed. In Bavaria, the project "Alternative weed management in fruit and wine growing with ecologically harmless substances and an alternative mulching method based on renewable raw materials - ABOW", submitted by the Technology and Promotion Centre in the Competence Centre for Renewable Resources (TFZ) Straubing together with the State Institute for Viticulture and Horticulture Veitshöchheim, was launched in January 2019. An Austrian project focusing on the development of an autonomous device and alternative substances in weed management was launched in summer 2019. In this project, the Institute of Plant Protection is investigating whether alternative natural substances and the sprayable mulch films developed in Bavaria have sufficient weed suppression.