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Uredo is a genus of rust fungi: long considered incertae sedis in the order Pucciniales, but now placed in the family Pucciniaceae. [2] This long-established genus, together with the closely-related Uromyces (which some authorities consider to be synonymous), give their names to "uredo-type" fungal spore structures such as "urediniospore" and uredinium".
The spores need several hours of dew or rain for spores to germinate and infect the host. [25] [26] Puccinia asparagi thrives where dews or fogs are prevalent because droplets of water are needed for successful infection of the host plant. [17] At 59 °F (15 °C) a three-hour, spore-wetting period is needed for initial infection.
Uromyces betae is a fungal species and plant pathogen infecting beet (Beta vulgaris). It was originally published as Uredo betae Pers. 1801 before it was transferred to the Uromyces genus. [2] Sugar beet rust was first described in Canada in 1935,(Newton and Peturson 1943), [3] and then reported in Europe in 1988 (O'Sullivan). [4]
Puccinia graminis is a macrocyclic heteroecious fungus that causes wheat stem rust disease. [citation needed] The sexual stage in this fungus occurs on the alternate host – barberry – and not wheat. The durable spore type produced on the alternate host allows the disease to persist in wheat even in more inhospitable environments.
Pustules develop on the leaves early in the season appearing as small creamy yellow spots. The spores produced in the pustules are aeciospores and spread the disease throughout the plant by wind. When these spores are released they are deposited as yellow powder. The aeciospores are found in chains of 7-8 spores and are sessile. [4]
Urediniospores are more or less reniform, 26–40 × 18-28 μm, with hyaline to pale yellowish wall, 1–2 μm thick, strongly warted on the convex side, smooth on the straight or concave side, warts frequently longer (3–7 μm) on spore edges. There have been no known reports of a host capable of supporting an aecial stage of the fungus. [5]
Uromyces dianthi is a fungus species and plant pathogen infecting carnations and Euphorbia. It was originally published as Uredo dianthi by mycologist Christiaan Hendrik Persoon in 1801, before it was transferred to the Uromyces genus in 1872 by Gustav Niessl von Mayendorf .
Zoospores are naked (wall-less), kidney-shaped and bi-flagellate. Both flagella are inserted laterally. Thick-walled sexual spores, called oospores are produced which germinate, producing either vesicles inside the plant tissue, exit tubes with vesicles at the tip, or germ tubes. Further zoospores develop inside the vesicles.