False loose smut

Taxobox
color = lightblue
name = "Ustilago nigra"
regnum = Fungi
phylum = Basidiomycota
classis = Ustilaginomycetes
subclassis = Ustilaginomycetidae
ordo = Ustilaginales
familia = Ustilaginaceae
genus = "Ustilago"
species = "U. nigra"
binomial = "Ustilago nigra"
binomial_authority = Tapke [cite web
url=http://www.speciesfungorum.org/Names/NamesRecord.asp?RecordID=253556
title=Index Fungorum - Names Record
publisher=www.speciesfungorum.org
accessdate=2008-03-16
last=
first=] (1932)
subspecies =
subspecies_authority =
synonyms =

False loose smut is a fungal disease of barley caused by "Ustilago nigra". This fungus is very similar to "U. nuda", the cause of loose smut, and was first distinguished from it in 1932.cite book
last = Mathre
first = D.E.
title = Compendium of barley diseases
publisher = American Phytopathological Society
date = 1997
pages = 120 pp ]

Symptoms

The disease is not apparent until heading, at which time, smutted heads emerge slightly earlier than healthy heads. At first, each smutted head is covered by a delicate, paperlike, grayish membrane. These membranes break shortly after the smutted heads have emerged and expose a dark brown to black, powdery mass of spores. This spores are easily dislodged, leaving only the bare rachis.cite book
last = Martens
first = J.W.
coauthors = W.L. Seaman, T.G. Atkinson
title = Diseases of field crops in Canada
publisher = Canadian Phytopathological Society
date = 1984
pages = 160 pp ]

Disease cycle

The disease cycle of "Ustilago nigra" is similar to that of "U. hordei", the cause of covered smut of barley. The teliospores survive on the surface or in the soil. In some cases, the teliospores that are deposited under the hull, may germinate immediately. The mycelium then grows into the lower layers of the seed and then remains dormant until seed germination.

Infection of seedling occurs between germination and emergence. Infection can occur from seed-borne teliospores or by teliospores residing in the soil. Relatively dry soil at temperatures of 15-21 C, are most favorable for infection. The invading mycelium becomes established within the growing point. As the plant enters the boot stage, the mycelium grows rapidly into the foral tissue which is converted to masses of black teliospores. Teliospores are disseminated by wind or during combining. The teliospores may remain viable for several spores.Disease cycle]

Management

The incidence of false loose smut can be reduced by using clean seed, treated seed and resistant cultivars.

References

External links

Extension publications

[http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=103 US: Oregon]