Covered smut of barley is caused by the fungus ''Ustilago hordei''. The disease is found worldwide and it is more extensively distributed than either loose smut or false loose smut.

Symptoms

Infected plants do not demonstrate symptoms until heading. Kernels of infected plants are replaced by masses of dark brown smut spores. Smutted heads are hard and compact. Infected plants may be stunted. Occasionally smut sori may also develop in leaf blades, where they appear as long streaks.

Disease cycle

Infection is seed-borne within the seed, the fungus penetrating the

endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the Embryo#Pla ...

while the grain is being formed. Infected seeds give rise to systemically infected plants. The

mycelium Mycelium (: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are fo ...

advances through the host tissue and becomes established behind the growing point. The

spores In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plant ...

are not readily blown or washed away by wind or rain. Spores are sticky in nature when present inside the membrane due to oily coating. At harvest, spore masses are broken up, scattering spores on grain. Frequently, masses of spores remain intact and appear in harvested grain. The fungus overwinters as

teliospore Teliospore (sometimes called teleutospore) is the thick-walled resting spore of some fungi (Rust (fungus), rusts and Smut (fungus), smuts), from which the basidium arises. Development They develop in ''telium, telia'' (sing. ''telium'' or ''telio ...

s on seed or in soil.

Pathotypes

At least 13 pathotypes are known; virulence is governed by at least three single recessive and independent gene pairs.

Management

Resistant cultivars and seed treatments are used to manage this disease.

Fungicides

Seed treatments: carboxin, fenpiclonil, tebuconazole, triadimenol, triticonazole.

References

External links

Extension publications

EPPO

Australia

Canada: Alberta

US: Oregon
{{Authority control Barley diseases Fungal plant pathogens and diseases Ustilaginomycotina