''Phragmidium '' is a genus of

rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH ...

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

that typically infects plant species in the family

Rosaceae Rosaceae (), the rose family, is a medium-sized family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus ''Rosa''. Among the most species-rich genera are ''Alchemilla'' (270), ''Sorbus ...

. It is characterised by having stalked

teliospore Teliospore (sometimes called teleutospore) is the thick-walled resting spore of some fungi ( rusts and smuts), from which the basidium arises. Development They develop in '' telia'' (sing. ''telium'' or ''teliosorus''). The telial host is the p ...

s borne on telia each having a row of four or more cells. All species have a

caeoma ''Caeoma'' is a genus of rust fungi. References External links * * ''Caeoma'' at Mycobank Basidiomycota genera Pucciniales {{basidiomycota-stub ...

which is a diffuse aecidium lacking a peridium. There are a number of species of ''Phragmidium'', most of which are restricted to one or a few host species. Examples include: *'' Phragmidium acuminatum'' on '' Rubus saxatile'' *'' Phragmidium bulbosum'' on ''

Rubus fruticosus ''Rubus fruticosus'' L. is the ambiguous name of a European blackberry species in the genus ''Rubus'' in the rose family. The name has been interpreted in several ways: *The species represented by the type specimen of ''Rubus fruticosus'' L., ...

'' and '' Rubeus caesius'' *'' Phragmidium mucronatum'' *'' Phragmidium sterilis'' on ''

Potentilla sterilis ''Potentilla sterilis'', also called strawberryleaf cinquefoil or barren strawberry, is a perennial herbaceous species of flowering plant in the rose family, Rosaceae. It is native to Europe. Description The plant looks rather like wild woodla ...

'' *''

Phragmidium potentillae ''Frommeella tormentillae'' is a species of rust fungus in the family Phragmidiaceae. It is a plant pathogen affecting the strawberry. See also * List of strawberry diseases This article is a list of diseases of strawberry (''Fragaria × ana ...

'' on ''

Potentilla anglica ''Potentilla'' is a genus containing over 300Guillén, A., et al. (2005)Reproductive biology of the Iberian species of ''Potentilla'' L. (Rosaceae).''Anales del Jardín Botánico de Madrid'' 1(62) 9–21. species of annual, biennial and perenni ...

'' *''

Phragmidium rosae-pimpinellifoliae ''Phragmidium rosae-pimpinellifoliae'' is a species of fungus in the family Phragmidiaceae The Phragmidiaceae are a family of rust fungi in the order Pucciniales. The family contains 14 genera and 164 species. Genera *'' Arthuriomyces'' *'' ...

'' *''

Phragmidium rubi-idaei ''Phragmidium rubi-idaei'' is a plant pathogen infecting caneberries, ''Rubus ''Rubus'' is a large and diverse genus of flowering plants in the rose family, Rosaceae, subfamily Rosoideae, with over 1,350 species. Raspberries, blackberries, ...

'' on

raspberry The raspberry is the edible fruit of a multitude of plant species in the genus ''Rubus'' of the rose family, most of which are in the subgenus '' Idaeobatus''. The name also applies to these plants themselves. Raspberries are perennial with w ...

*''

Phragmidium tuberculatum ''Phragmidium '' is a genus of Rust (fungus), rust fungus that typically infects plant species in the family Rosaceae. It is characterised by having stalked teliospores borne on telium, telia each having a row of four or more cells. All species ...

'' on some

rose A rose is either a woody perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be ...

cultivars *''

Phragmidium violaceum ''Phragmidium violaceum'' is a plant pathogen native to Europe, Africa, and the Middle East. It primarily infects ''Rubus'' species. It has been used in the biological control of invasive blackberry species in Chile, Australia, and New Zealand ...

'' on cultivated

blackberry The blackberry is an edible fruit produced by many species in the genus ''Rubus'' in the family Rosaceae, hybrids among these species within the subgenus ''Rubus'', and hybrids between the subgenera ''Rubus'' and ''Idaeobatus''. The taxonomy of ...

and

loganberry The loganberry (''Rubus'' × ''loganobaccus'') is a hybrid of the North American blackberry (''Rubus ursinus'') and the European raspberry (''Rubus idaeus''). The plant and the fruit resemble the blackberry more than the raspberry, but the frui ...

Possibly the most commonly encountered is ''P. mucronatum'', found on most species of wild roses including ''

Rosa canina ''Rosa canina'', commonly known as the dog rose, is a variable climbing, wild rose species native to Europe, northwest Africa, and western Asia. Description The dog rose is a deciduous shrub normally ranging in height from , though sometimes it ...

'' and ''

Rosa arvensis ''Rosa arvensis'', the field rose, is a species of wild rose native to Western, Central and Southern Europe. Names The plant is variously known as the field rose and white-flowered trailing rose. It may also be called Shakespeare’s musk. Cl ...

''.

Hosts and symptoms

''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.

Environment

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.

Disease cycle

In the spring, the very first spores, spermatogonia, arise out of the debris on the ground and infects the young stem, distorting them and producing orange pustules. These pustules break open and infect the leaves. In the Summer, these darker orange spores called urediniospores spread through wind. Eventually in late August, the urediniospores and sori become speckled with black fascicles and dark resting spores called teliospores. The teliospores turn into aeciospores which are the spores that adhere to stems and leaves to overwinter.

Pathology

Roses infected with species of ''Phragmidium'' will show a characteristic orange mass of spores and distorted growth at specific locations on the bush. The rose may be substantially weakened and lack vigour and may die. Later in the year, small black spots or raised areas will be visible. These are telia containing overwintering

Prevention

Rose growers recommend the use of

fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

s some of which may have health implications for the gardener.Fungicides: Chemistry, Environmental Impact and Health Effects, Costa and Bezerra Many cultivated roses are now bred to have resistance to rust diseases. In wild roses, Phragmidium infections are one of a normal range of pests and diseases which are part of the normal

ecological Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

pressures affecting all species. Non-chemical controls include pruning out the spring infections as soon as possible along with collecting and destroying fallen leaves to prevent overwintering.

References

External links

*http://www.apsnet.org/publications/plantdisease/2014/November/Pages/98_11_1581.2.aspx *http://hort.uwex.edu/articles/rose-rust/ * {{Taxonbar, from=Q369337 Fungal plant pathogens and diseases Pucciniales Taxa described in 1815 Taxa named by Johann Heinrich Friedrich Link Basidiomycota genera