Ustilago crameri Syd.

Description

Sori in all spikelets of an inflorescence, destroying the ovaries and the basal part of the inner floral envelopes which become bullate, the upper parts of the envelopes and the two glumes appearing unaffected. Sori at first covered by a green, yellow or silvery peridium of host origin which ruptures irregularly exposing the dark brown powdery mass of spores.

Spores variable in shape, subglobose to elongate, slightly bent, irregular, subpolyhedral, pyriform, lemon- or drop-shaped, sometimes with an acute tip, 8–12 (–15) × (6–) 7.0–9.5 µm, medium dark reddish brown; wall uniformly c. 0.5 µm thick, smooth; in SEM smooth or with sparse low warts.

Hosts
   
Host family: Poaceae
   
Host species: Setaria italica (L.) P.Beauv.

Distribution

States & Territories: NSW

Comments

Ustilago crameri causes kernel smut on foxtail millet (Setaria italica) which is a minor crop cultivated for hay or as a grain for birdseed. Kernel smut can be controlled with seed treatment at planting. The spores of the Australian specimens are mostly subglobose to elongate, being more regular in shape than specimens from elsewhere.