Diseases

Downy Mildew — Impatiens walleriana

Impatiens walleriana Hook. f.

A destructive disease of Impatiens walleriana caused by the obligate oomycete Plasmopara destructor. It is characterized by a latent period of development and the potential to cause mass leaf drop and plant death.

In the reference 18 varieties crop Busy Lizzie, where this is mentioned in the description.

The pathogen Plasmopara destructor persists in the soil as long-lived oospores capable of surviving in plant debris for years. The infection process is accompanied by the development of symptoms within 5–14 days post-inoculation, manifesting as chlorotic spots, mottling, and downward leaf curling.

A white downy fungal mat, representing the sporulation of the pathogen, forms on the underside of leaf blades. In the progression phase of the disease, bud abortion and stem defoliation are observed, which, under high humidity, culminate in the rapid collapse of the entire plant.

Specific resistance genes have not been standardized; however, breeding efforts are focused on the introgression of resistance sources from germplasm material monitored by molecular markers. Resistant cultivars demonstrate significant genetic protection, distinct from susceptible lines.

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

Sources8

Varieties of Busy Lizzie 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.