False loose smut is a fungal disease of
barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...
caused by ''Ustilago nigra''. This fungus is very similar to ''
U. nuda'', the cause of
loose smut
Loose smut of barley is caused by ''Ustilago nuda''.
It is a disease that can destroy a large proportion of a barley crop. Loose smut replaces grain heads with smut, or masses of spores which infect the open flowers of healthy plants and grow ...
, and was first distinguished from it in 1932.
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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.
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Disease cycle
The disease cycle of ''Ustilago nigra'' is similar to that of ''
U. hordei'', the cause of
covered smut
Common bunt, also known as hill bunt, Indian bunt European bunt, stinking smut or covered smut, is a disease of both spring and winter wheats. It is caused by two very closely related fungi, '' Tilletia tritici'' (syn. '' Tilletia caries'') and '' ...
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 floral 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.
Management
The incidence of false loose smut can be reduced by using clean seed, treated seed and resistant cultivars.
References
External links
Extension publications
US: Oregon
{{Taxonbar, from=Q5432714
Fungal plant pathogens and diseases
Barley diseases
Ustilaginomycotina
Fungi described in 1932