“What caused it?” matters the most when a plant suffers from a disease. A correct identification of the involved pathogen is a prerequisite for all further analysis concerning its biology and epidemiology. Knowing its exact type allows to take measures against the pathogen to maintain the health of the plant.

Fungi, bacteria, viruses, and nematodes are among the most important pathogens threatening our crop plants. Since these organisms are microscopically small, only a light or electron microscope can make them visible. Their correct identification is often difficult due to their tininess and enormous diversity, and due to the fact that the symptoms they cause are rarely host plant specific. Globalisation and the further growing exchange of goods on the one hand, and increasing numbers of travelers on the other hand result in the fact that, without being noticed, pathogens are frequently and fast covering far distances and are thus easily spread into new areas. Due to the climatic change this may happen beyond human influence and may have considerable ecological and economical consequences, a worst-case scenario being that individual plants can no longer be cultivated in certain regions and may even become extinct. A successful control of the pathogens necessitates fast and reliable methods for diagnosis.

Usually, microorganisms have a very short generation period ranging from minutes up to a few hours. This means rapid changes and fast adaptation, constantly forming new variants of known pathogens which, for example, are able to attack other species of cultivated plants, or to overcome species-specific resistances. The characterisation of such pathogen variants is of seminal importance for the breeding of new resistant varieties.

We apply and develop diagnostic methods which are fast, specific, sensitive, and robust. We use light and electron microscopical, serological, and molecular biological (mainly based on DNA and RNA) methods allowing the qualitative and quantitative identification of pathogens. We maintain a huge collection of plant pathogens for comparisons and as reference material, as well as a wide variety of diagnostic antibodies for virus detection.

Robust methods for a reliable identification of pathogens in plants, vectors, and environmental samples are an indispensable prerequisite for taking effective and appropriate measures to keep our cultivated plants healthy.