Organic fertilization shapes the biodiversity of fungal communities associated with potato dry rot

Intensive farming based on synthetic pesticides and mineral fertilizers has led to a loss of soil biodiversity, which contributes to the suppression of plant pathogens. The key role in the restoration of biodiversity and soil aggregate stability is fulfilled by organic fertilization. Potato reacts well to this type of fertilization. On the other hand, its tubers, during both the vegetative and storage periods, are exposed to a series of infections caused by soil fungi. Of particular economic importance is dry rot, a storage disease with a complex etiology. This study presents an evaluation of the impact of different organic fertilization forms (manure, white mustard intercrop, barley stubble, barley straw and a combination of barley straw and white mustard intercrop) on losses caused by dry rot. For the first time, their role in the formation of: counts, species composition and belonging to frequency and trophic groups of fungi communities colonizing dry-rotting tubers has been specified. Furthermore, a pioneering element of this research is its evaluation of fungi community biodiversity and its influence on the development of dry rot. The main discoveries are as follows: (i) 24 fungi species (14 pathogenic, 6 saprotrophic, 4 antagonistic), which are the cause of dry rot; (ii) dry rot development is mainly determined by the share of saprotrophic fungi, where their increase reduces the percentage of infected tubers; (iii) manure and white mustard favors tuber colonization by saprotrophic and antagonistic fungi and increases biodiversity of the fungi, which results in improved healthiness; (iv) straw and a lack of fertilization increase the frequency of pathogens and reduce biodiversity, resulting in a stronger development of dry rot. In sustainable agriculture management systems, disease risk can be minimized through introduction of organic matter to soil.