KORaruli
ActiveRosa L. · Rose
Margarita Kordes^^^Wilhelm Kordes^^^Tim-Hermann Kordes
Diseases
Erysiphales
Powdery mildew is a fungal disease manifesting as a white web-like coating on plant organs, leading to tissue necrosis, fruit deformation, and significant crop losses.
Mentioned in descriptions 33 570 varieties reference book.
Powdery mildew is caused by ectoparasitic fungi of the order Erysiphales, which develop primarily on the surface of leaves, shoots, and fruits. The initial white web-like coating eventually densifies into "powdery" cushions, upon which fungal fruiting bodies may form as dark spots. As a result of the infection, tissues turn yellow and become necrotic, fruits may crack, and leaves drop prematurely.
The intensity of disease development depends on a complex of factors: high relative humidity, moderate temperatures, the presence of dense canopy, and excessive nitrogen nutrition. Risks increase with alternating dry and wet weather. The harmfulness of the disease is expressed in a reduction of the leaf assimilation area, deterioration of crop quality, and a decrease in the general winter hardiness of crops.
Assessment of variety resistance is conducted under field conditions at various stages of vegetation, most often during the full heading phase. To classify the degree of infection, scoring systems or intensity scales in percentages are used, where varieties with up to 10% infection are considered highly resistant (R), 11 to 40% as moderately resistant (M), and more than 41% as susceptible (S). Variety resistance is ensured by genetic mechanisms that prevent colonization by the pathogen or limit the development of its mycelium.
Selection based on the description text, not official resistance ratings: such data is not available in registers. Mention indicates that the trait is discussed in the variety's sources; see the variety's profile for details on what is specifically stated.
Rosa L. · Rose
Margarita Kordes^^^Wilhelm Kordes^^^Tim-Hermann Kordes
Rosa L. · Rose
WILHELM-ALEXANDER KORDES
Vitis L. · Grapevine
Peter Hempstad
Rosa L. · Rose
Interplant Roses B.V
Lagerstroemia indica L. · Crape myrtle
Lagerstroemia S.A.R.L.
Calibrachoa Cerv. · Calibrachoa
Losert Dominik
Lolium multiflorum Lam. · Italian ryegrass
DLF SEEDS A/S
Rosa L. · Rose
Harkness, Robert|Mougins, France
Viburnum plicatum Thunb. · Japanese snowball
Wezelenburg Jan-Willem
Lagerstroemia indica L. · Crape myrtle
Lagerstroemia S.A.R.L.
Clematis L. · Clematis
RAYMOND J. EVISON^^^POULSEN ROSER INTERNATIONAL S.A.R.L.
Coreopsis L. · Tickseed
Korlipara Harini
Heuchera L. · Coral Flower
Janet N. Egger
Monarda didyma L. · Bee balm
Oudshoorn Hubertus Gerardus
Heuchera L. · Coral Flower
Janet N. Egger
Clematis L. · Clematis
HAYAKAWA HIROSHI
Achillea ptarmica L.
ROBERT PIERCE
Salvia L. · Sage
Petrus Hendricus Oudolf
Oenothera lindheimeri (Engelm. & A. Gray) W. L. Wagner & Hoch · Lindheimer's beeblossom
Syngenta Seeds B.V.
Rosa L. · Rose
Hooijman Aloysius A. J.
Rosa L. · Rose
Hooijman Aloysius A. J.
Phlox paniculata L. · Garden phlox
Oudshoorn Hubertus Gerardus
Hordeum vulgare L. · Barley
Syngenta UK Ltd
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Leis Michelangelo/ Castagnoli Gianfranco/ Martinelli Alessio