Choice of variety

In principle, the choice of variety is always dependent on the variety requirements. Extremely important with regard to disease resistance of a variety is the resistance of a plant to biotic and abiotic factors (e.g.: reduced stress to drought, frost, heat and UV radiation) in order to keep the susceptibility to pathogens as low as possible. There are more or less pathogen resistant varieties of all cultivated species. In organic farming, less disease-susceptible, traditional (if possible native) varieties are preferred. In some cases, however, the flavor and yield of the variety are more important than existing resistance. A certain degree of yield loss due to diseases, among other things, is accepted.

The robustness of the plant is defined - in addition to its resistance to abiotic factors - by its ability to repel diseases. The thickness of the epidermis and the wax layer (cuticle) on top of it, as well as strengthening deposits (silicic acid) in the cell walls, play a decisive role here. Thicker-skinned cultivars have an advantage over thin-skinned ones.

While powdery mildew resistance is a priority for all crops, especially in organic farming, additional attention is paid to fungal diseases such as Erysiphe necator and Plasmopara viticola in wine. In organic fruit and wine growing, more and more areas are being planted with new fungus-resistant (PIWI) varieties. In fruit crops, resistant varieties against scab, (Venturia), leaf blotch (Marssonina), fire blight (apple), curl disease (peach), Scharka virus (Plum-pox virus), canker and storage rot (Gloeosporium) and generally disease-resistant raspberry varieties are available.

In arable crops, the focus in resistance breeding is on leaf diseases and Fusarium head blight in cereals, late blight in potato, leaf diseases and corn smut (Ustilago maydis), and Sclerotina, Phomopsis, grey mould rot of the basket in sunflower (Botrytis cineraria).For sugar beets Rhizoctonia-resistant varieties and Cercospora leaf blight susceptible and tolerant cultivars are available.

In horticulture, late blight-resistant varieties in tomatoes and cucumber mosaic-resistant varieties in cucumbers have been bred.

Furthermore, disease pressure from certain pathogens can be circumvented by varieties with suitable planting and harvest dates. For example, early wine varieties are somewhat less likely to be infected late with Botrytis. The likelihood of rain and risk of injury is reduced because the grapes are already harvested in summer.