Diseases

Powdery mildew of Penstemon

Penstemon Schmidel.

A fungal disease of the ornamental plant genus Penstemon, caused by pathogens of the genera Erysiphe and Oidium. It manifests as a white coating on vegetative organs, leading to shoot deformation and premature leaf drop.

In the reference 8 varieties crop Beard Tongue, where this is mentioned in the description.

The pathogens of powdery mildew on Penstemon are most commonly fungi of the genus Erysiphe, including Erysiphe polygoni, and their anamorph stage Oidium. The disease is characterized by the appearance of a white or grayish powdery coating on the leaves and stems, consisting of the pathogen's mycelium and conidia.

The development of the infection leads to yellowing, desiccation, and necrosis of the leaf apparatus. In severe cases, deformation of young shoots and overall stunted plant growth are observed. The pathogen spreads actively under conditions of poor air circulation and high humidity, although spore germination is possible even at moderate humidity levels without the presence of free moisture.

The genetic basis of resistance to this disease in Penstemon has not been studied, and specific resistance genes have not been identified. The resistance of existing varieties is assessed solely based on field observations and variety trial results, without the use of molecular genetic markers.

General information about the subject — on the page Powdery mildew.

Sources8

Varieties of Beard Tongue mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.