The reed glasswing cicada is causing significant crop damage in southern Germany, impacting sugar beet and increasingly potatoes, leading to losses up to 50%. In Switzerland, yield reductions of 30% are anticipated, affecting the baking quality of processing potatoes. The cicada may transmit harmful bacteria to plants. Solutions like crop rotation are being explored, but challenges remain due to climatic factors and the cicada’s potential spread to other crops.
Overview: The reed glasswing cicada is significantly impacting crop yields in southern Germany, with losses reaching up to 50%. Initially a threat to sugar beet, this pest is now also targeting potato crops. In Switzerland, the situation is not as severe yet but is resulting in notable quality issues, particularly for potatoes designated for processing. Stefan Vogel, an agronomist and potato specialist at the BFH-HAFL School of Agricultural, Forest and Food Sciences, explains that the potato industry has faced increasing challenges in the past two years.
Impact of Infestation: The cicada damages crops primarily when it transmits the bacteria “Arsenophonus” or “Phytoplasma solani”. Between May and mid-July, the cicadas invade fields to feed on leaves. If infected, they pass the bacteria to plants, leading to symptoms such as yellow leaves and reduced sugar levels in sugar beets. In potatoes, the consequences can manifest as wilting or air pockets just above the soil. The precise effects on plant health are still under investigation.
Consequences for Yield: In Switzerland, agronomists predict yield reductions of up to 30%. A critical concern is that the quality of processing potatoes is declining, leading to undesirable browning when fried. This situation hampers local producers from maintaining product standards, resulting in increased imports of chips and potato products.
Potential for Broader Infestation: Experts remain uncertain about the cicadas’ capacity to affect other crops. A collaborative project has been initiated this year involving the potato sector, Agroscope, and Bioreba to explore this issue further. Currently, reed glasswing cicadas have been observed on potatoes, sugar beets, and some vegetable crops like celery. There are suspicions in Germany that they could also threaten onion crops.
Strategies for Control: Previous research has explored the feasibility of controlling cicada populations through crop rotation, as they typically lay eggs on sugar beets. The emerging nymphs feed on the beet and continue to damage subsequent crops, usually winter wheat. Findings suggest that planting fallow land after sugar beets, followed by a spring crop like maize, could significantly reduce cicada survival by limiting food sources.
Nonetheless, implementing such rotation across all sugar beet and potato cultivation areas would pose challenges. Other management strategies are essential to counter the impact of these pests. Additionally, environmental factors, such as this year’s cooler temperatures and increased rainfall, contribute to diminished yields compared to the previous years.