Urocystis occulta (Wallr.) Rabenh. ex L. Fuckel

Synonyms

Erysibe occulta α secales Wallr.
Polycystis occulta (Wallr.) Schltdl.
Polycystis parallela (Berk.) Berk. & Broome
Polycystis parallela (Berk.) Fr.
Tuburcinia hordei Cif.
Tuburcinia occulta (Wallr.) Liro
Uredo parallela Berk.
Urocystis hordei (Cif.) Zundel
Urocystis occulta (Wallr.) Rabenh.
Urocystis parallela (Berk.) A.A. Fisch. Waldh.
Ustilago occulta (Wallr.) Rabenh.

Description

Sori often in markedly deformed leaves, sheaths, culms and spikes, appearing as long and sometimes confluent streaks, at first lead-coloured, covered by the epidermis which ruptures longitudinally exposing the reddish black dusty mass of spore balls.

Spore balls subglobose, ovoid to irregular, (12–) 16–30 (–40) × (10.5–) 13.5–20.0 µm diam., composed of 1–3 (–5) spores and surrounded by a layer of sterile cells which is usually incomplete but varies from complete to absent.

Spores subglobose, ovoid, elongate to irregular, often with flattened sides, (11.0–) 13.0–20.0 (–22.5) × (8.0–) 10.0–13.5 (–16.0) µm, reddish brown, smooth, with finely granular contents.

Sterile cells subglobose, ovoid to irregular, 6–13 µm long, pale yellow, smooth.

Spore germination resulting in aseptate basidia of variable length, bearing (2–) 4–6 apical elongate basidiospores.

Hosts
   
Host family: Poaceae
   
Host species: Secale cereale L.

Distribution

States & Territories: VIC (although there is no confirmed report on field crops in Australia)

Comments

McAlpine’s (1910) report of U. occulta in Australia was based on specimens of rye plants that had been inoculated with spores of the smut sent to him from Germany by Sydow (Langdon et al., 1976).