Ameris Arthur (1906)
Aregma Fr. (1815)
Earlea Arthur (1906)
Epitea Fr. (1832)
Frommea Arthur (1917)
Lecythea Lév. (1847)
Phragmidiopsis (G.Winter) Mussat (1901)
Phragmotelium Syd. (1921)
Physonema Lév. (1847)
Teloconia Syd. (1921)
Trolliomyces Ulbr. (1938)
Phragmidium is a genus of rust fungus that typically infects plant species in the family 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 peridium.[2]
There are a number of species of Phragmidium, most of which are restricted to one or a few host species. Examples include:
Possibly the most commonly encountered is P. mucronatum, found on most species of wild roses including Rosa canina and Rosa arvensis.[3]
Phragmidium tuberculatum, also known as rose rust, is a parasitic fungus that feeds on living cells of a host plant. It can affect all species of the family Rosaceae. This includes all species of roses. Rose rust causes distortion and discoloration on stems. Sometimes it will cause galls and lesions. In the spring, there are yellow spots on the upper portion of the leaf and during the Spring and Summer there are orange spores on the abaxial surface of the leaf.[citation needed]
The climate most favorable to rose rust is mild temperatures with high moisture. Most of this strain of Phragmidium is found in Europe but there have been cases found in Asia and North America. Most of the cases of rose rust in the United States are found on the coasts, mainly the Pacific Coast. The Midwest is poor for this pathogen because of its extreme winter and summer temperatures.[citation needed]