Institut für Pflanzenschutz in Ackerbau und Grünland
Potato starch is becoming increasingly important as a renewable raw material for various applications. The health of the plant, in particular a good supply of nutrients, is crucial for the formation of high-quality starch molecules. Fungal diseases that lead to premature death of the plant, for example, have a negative impact on the starch yield. The most important fungal diseases affecting potatoes worldwide include late blight (Phytophthora infestans) and root rot (Rhizoctonia solani). The use of fungicides is the most common control strategy against P. infestans. Infections with the basidiomycete R. solani pose challenges for cultivation due to a lack of resources, contaminated soils and infected plant material. As a result, there is an urgent need for new, sustainable measures. In this study, the effect of kraft lignin on the occurrence of various fungal diseases in the cultivation of starch potatoes is to be investigated and methods for practical use developed. Furthermore, the effects of kraft lignin on the starch content and the microbiome in the tuber-adhering soil will be characterised. Various application methods, in particular the incorporation of kraft lignin into the soil and a spray application, will be tested for their suitability in greenhouses and field trials. Kraft lignin will be applied in pure form (as a solid), in combination with antagonsites (Trichoderma spp.) and in liquid form. Lignin is a natural, biodegradable polymer that provides plants with mechanical support and is also involved in defence against pests and diseases. The defence function is due to the molecular structure of polyphenolic compounds, which cause damage to the cell membrane and lysis with subsequent release of the cell contents. The so-called kraft lignin is a technical lignin that is a by-product of cellulose production. Initial studies on the use of kraft lignin in horticulture are particularly promising. This shows an effect against R. solani on lettuce, presumably due to the promotion of lignin-degrading microorganisms, which displace the pathogen from the rhizosphere. Other studies made it possible to reduce copper application rates in the cultivation of tomatoes and strawberries.In Germany, integrated pest management (IPM) forms the basis for the production of healthy plants. However, safe IPM strategies are always based on a combination of several approaches: Preventive measures, such as predicting a disease outbreak, good cultivation practices and, lastly, the application of plant protection products. However, limited resistance in the pool of cultivated varieties and the decreasing availability of active substances for successful resistance management pose major challenges in practice. The development of new biological alternatives based on low-risk substances is therefore essential for expanding the catalogue of IPM measures for potatoes. However, it is essential to prove the success of these measures under field conditions in order to make a reliable assessment regarding the safeguarding of yields while minimising the use of conventional plant protection products.As part of the Kraft & Stärke project, two-year field trials are to be carried out at 3 locations in Germany. The same two varieties are to be cultivated at all locations each year. In addition to the field trials under practical conditions, greenhouse trials will be carried out under defined conditions to ensure that the effects observed cannot be attributed to environmental influences at a single location. In order to enable a high infection pressure, the pathogens P. infestans and R. solani will be specifically inoculated using methods already established at the JKI. During the cultivation phases, the infestation with P. infestans will be documented using a drone. In order to examine changes in the microbial composition of the tubers, samples of the soil adhering to the tubers will be taken. The composition and diversity of the fungi in the soil samples will then be analysed using modern high-throughput sequencing methods. After harvesting, the degree of infestation with R. solani will be determined on the basis of the sclerotia on the tuber surface and the starch concentration will be determined.
Federal Ministry of Agriculture, Food and Regional Identity
