Rose rust
Encyclopedia
Rose
rust is a disease affecting the rose shrub
caused by a number of fungi (such as Phragmidium tuberculatum
). The spores of the rose rust fungi infect the leaves of the shrub during the beginning of summer, resulting in the appearance of orange pustules. Towards the end of summer, the orange pustules are superseded by black pustules, which contain overwintering spores.
Rose rust often causes the death of a rose shrub, with severe infections resulting in a weakening of the plant (and, in serious cases, death) due to premature defoliation.
Rose
A rose is a woody perennial of the genus Rosa, within the family Rosaceae. There are over 100 species. They form a group of erect shrubs, and climbing or trailing plants, with stems that are often armed with sharp prickles. Flowers are large and showy, in colours ranging from white through yellows...
rust is a disease affecting the rose shrub
Pests and diseases of roses
Roses are susceptible to a number of pests, diseases and disorders. A large number of the problems affecting roses are seasonal and climatic. Certain varieties of roses are naturally more resistant or immune than others to certain pests and diseases...
caused by a number of fungi (such as Phragmidium tuberculatum
Phragmidium
Phragmidium is a genus of rust fungus that typically infects plant species in the Rosaceae. It is characterised by having stalked teliospores borne on telia each having a row of four or more cells. All species have a caeoma which is a diffuse aecidium lacking a peridiumThere are a number of...
). The spores of the rose rust fungi infect the leaves of the shrub during the beginning of summer, resulting in the appearance of orange pustules. Towards the end of summer, the orange pustules are superseded by black pustules, which contain overwintering spores.
Rose rust often causes the death of a rose shrub, with severe infections resulting in a weakening of the plant (and, in serious cases, death) due to premature defoliation.
Symptoms
- On stems: In spring, distorted young green stems, with large pustules of bright orange dusty spores.
- On leaves: Yellow spots on the upper surfaces, corresponding to pustules of dusty orange spores on the lower surface. In late summer, the orange pustules turn black. Infected leaves may fall early.
Treatment
Rose rust can be treated by pruning out spring infections as soon as they emerge and removing fallen leaves promptly during autumn. If infections are persistently troublesome, it may be that the cultivar concerned is unusually susceptible, and it may be necessary to replace it.Further reading
- Royal Horticultural Society, entry on rose rust.