Importance, Biology, Epidemiology, and Management of Loose Smut (Ustilago nuda) of Barley (Hordeum vulgare): A Review

  • Mashilla Dejene Woldemichael
Keywords: Barley; loose smut; seedborne fungi; seed treatment; Ustilago nuda; yield loss.

Abstract

Barley (Hordeum vulgare) is an economically, nutritionally and industrially important cereal crop
worldwide. Ethiopia is believed to be the center of origin and diversity of the cultivated barley crop. The
crop has been cultivated in the country since time immemorial. The midlands and highlands of Ethiopia
are suitable for barley cultivation. However, there are many biotic and abiotic factors that reduce
production and productivity of the crop in Ethiopia and elsewhere. Of the various fungal plant diseases
limiting barley productivity, loose smut (Ustilago nuda) is one of the major cosmopolitan and destructive
seedborne pathogen in many barley-producing countries in the world. This piece of work was undertaken
to: 1) review the economic importance and ecological requirements of barley and extent of grain loss due
to barley loose smut; 2) review the biology and ecological requirements of the pathogen leading to
epidemics; and 3) compile the management options for sustainable barley production and productivity. To
achieve these objectives, data and information were gleaned from scientific journal publications, PhD
dissertations, Master’s theses, research reports, books and book chapters, proceedings and symposia
papers, relevant compendia, internet resources, personal communications, and similar other resources.
From the reviews made, it could be deduced that barley loose smut on average causes estimated grain
yield losses that range from 25 to 30% in the world. The systemic pathogen is embedded in the scutellum
part of the embryo and easily transmitted to the next cropping season. The pathogen sori commonly
replace the spike during anthesis and healthy ears are infected at flowering through the teliospores blown
by wind. Warm soil when seedlings emerge is more conducive to loose smut than cold soil; however,
moderate temperature (15 to 22 oC) and damp cloudy weather or heavy rainfall at flowering time are the
preconditions required by the pathogen for heavy infection because of elongated or extended period of
open flowers. Barley loose smut can be better managed through the use of proper cultural practices in
integration with hot water and solar heat seed treatment, use of resistant varieties, and effective systemic
fungicides, like Azoxystrobin, Carboxin, Difenoconazole, Mancozeb, Propiconazole, Tebuconazole,
Triadimenol, and Triticonazole. It could, thus, be concluded that barley loose smut is a very important
disease that seriously affects barley production and productivity worldwide, but can be reasonably
managed through the use of smut-free seed, certified seed, host resistance, and hot water/solar heat or
systemic fungicidal seed treatment or their integration.

Author Biography

Mashilla Dejene Woldemichael

School of Plant Sciences, Haramaya University, P.O. Box 138, Dire Dawa, Ethiopia

Published
2019-09-02

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