Tilletia ehrhartae Talbot

Description

Sori infecting all ovaries in the inflorescence, ovoid to broadly fusiform, 2–6 mm long, 1–2 mm wide, partly hidden by the floral envelopes, at first covered by a thick peridium of host origin (modified pericarp) which ruptures irregularly early exposing the blackish brown powdery mass of spores mixed with sterile cells.

Spores globose, subglobose, more rarely broadly ellipsoidal, 17.5–24.0 × 17.5–22.0 µm, yellowish to dark reddish brown; wall uniformly thick, endospore c. 0.5 µm, exospore with 1.5–2.5 (–3.0) µm high cylindrical or subpyramidal ornamentation with flattened tips; in surface view these appearing as darker irregularly polygonal areas, 6–10 per spore diameter, frequently fusing.

Sterile cells subglobose, ovoid to slightly irregular, 12–28 × 10–24 µm, subhyaline to pale yellowish brown; wall 1.5–5.0 µm thick, smooth.

Hosts
   
Host family: Poaceae
   
Host species: Ehrharta calycina Sm.

Distribution

States & Territories: SA, VIC, WA

Comments

Infected plants are often found on roadsides adjacent to wheat crops. During harvesting, spores can settle on wheat seed as contaminants. On one occasion in 2004 the misidentification of T. ehrhartae (as T. indica Mitra, which is absent from Australia) in exported wheat seed, threatened to harm Australia’s billion dollar wheat industry (Pascoe et al., 2005b). Durán & Fischer (1961: 99) considered T. ehrhartae to be a synonym of T. rugispora Ellis & Everh. (type on Paspalum plicatulum Michx., U.S.A.), another smut fungus that does not occur in Australia.