Poland's Soybean Growers Face New Disease Threats, Led by Fungal Infections
At a Polish expert forum, specialists said fungal, viral and bacterial diseases are increasing in soybean fields, many spreading via seed. They urged the use of certified seed and a wider range of approved fungicides.
Soybean growers in Poland are dealing with a growing number of plant health problems. The issue was discussed at the forum "Soy in Poland – Potential and Prospects", held on 3–4 November in Ożarów Mazowiecki and attended by researchers from the Institute of Plant Protection (IOR-PIB) and industry representatives. It was organised by the Polska Soja association and two national research institutes.
Fungi behind misdiagnosed symptoms
Dr Sylwia Stępniewska-Jarosz of IOR-PIB said clear signals of new soybean problems began reaching the institute's plant disease clinic in 2024. Farmers and seed producers reported spotted, cracked and wrinkled seeds with reduced germination. Soybean mosaic virus was the first suspect, but in about 90% of cases no viruses were found. After mycological testing was added, the scale of fungal infection became clear: 30–50% of seeds in samples were affected, and sometimes all of them.
The main fungi identified were the Diaporthe/Phomopsis complex, Fusarium and Cercospora. In 2025 some seed lots had more than half of the material colonised by Diaporthe, which can also cause stem damage and stunted plants. According to the expert, Cercospora is becoming more frequent, and severely infected plants may set far fewer seeds. Downy mildew and septoria leaf spot were also recorded locally.
Viruses and bacteria
Viral diseases cannot be controlled with fungicides, so seed quality is key. Other viruses already present in neighbouring countries are expected to appear, and bacterial diseases are starting to emerge on soybeans.
Certified seed and crop protection
Emilia Fink-Podyma, president of Polska Soja, noted that some seed had germination above 90% yet tested positive for Diaporthe in the laboratory. After such tests, some growers switched to certified seed. She added that only two fungicide active substances are currently available for soybeans, and they cover only some of the diseases.
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