Ustilago maydis (DC.) Corda

Synonyms

Caeoma zeae Link
Erysibe maydis (DC.) Wallr.
Lycoperdon zeae Beckm.
Mycosarcoma maydis (DC.) Bref.
Uredo maydis DC.
Uredo segetum δ mays-zeae DC.
Uredo segetum η Uredo zea-mays DC.
Uredo [subgen.] Ustilago zeae Schwein.
Ustilago euchlaenae Archangeli
Ustilago mays-zeae (DC.) Magnus
Ustilago zeae (Link) Unger
Ustilago zeae-mays (DC.) G. Winter

Description

Sori in stems, leaves and inflorescences (male and female), as pustules or irregular galls of considerable size, at first covered by a thin greyish silvery, later brown smooth membrane that ruptures irregularly to expose the medium to dark brown powdery spore mass.

Spores globose, subglobose, ovoid or sometimes elongate or slightly irregular, 7–13 × 7–11 µm, light olivaceous brown; wall c. 0.5 µm thick, finely and rather densely echinulate.

Spore germination resulting in a 4-celled basidium bearing lateral and terminal basidiospores. Frequently, the upper half of the young basidium separates from the lower by a fragmentation zone. Mycelium mostly intracellular.

Hosts
   
Host family: Poaceae
   
Host species: Zea mays L.

Distribution

States & Territories: NSW, QLD, VIC

Comments

Ustilago maydis causes boil smut, an important disease of cultivated maize in many countries. The disease was first recorded in Australia at Bathurst, New South Wales in 1911 and recurred sporadically until 1940 when quarantine restrictions prevented maize being grown on affected properties (Nuberg et al., 1986). No further outbreaks were recorded until 1982, when boil smut was found to be widespread in north-eastern New South Wales and south-eastern Queensland (Allen & Jones, 1983). The pathogen has continued to spread, although it has not reached the maize-growing areas of Western Australia. Boil smut of maize can be controlled by the use of resistant varieties and hybrids as well as chemical seed treatments (Jones, 1986).