Loose smut of wheat

Ustilago tritici

Description
Loose smut of wheat is caused by the basidiomyceteous fungus Ustilago tritici (Teliomycetes, Ustilaginales).

Damage
Loose smut causes no detectable symptoms until heading of plants. Infected plants often produce heads earlier and are taller than non-infected ones. Usually all spikelets of the ear are transformed into a mass of olive-green teliospores forming smut masses. Smutted kernels are initially covered by a thin grayish membrane, which bursts and releases the powdery spores when mature. Spores are dispersed within a few days and a naked, blackish and erect rachis remains visible above the healthy crop at maturity.

Cause
The fungus is strictly seed-borne and enters the field within the embryos of seed in which it was established earlier by infecting the seed crop during anthesis.

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