Spot blotch (barley)

Spot blotch is a disease of barley caused by "Cochliobolus sativus". The disease is found everywhere that barley is grown, but only significant yield losses in warm, humid climates.cite book
last = Mathre
first = D.E.
title = Compendium of barley diseases
publisher = American Phytopathological Society
date = 1997
pages = 120 pp ] 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 ]

Symptoms

Infections appear as dark, chocolate-colored blotches. The spots merge, eventually forming irregular dead patches on the leaves. Leaf spots may be surrounded by a zone of yellow leaf tissue of varying width. Spot may also appear on the leaf sheaths, necks and heads of the plant. Heavily infected leaves dry up completely, and infections on the flag leaf during kernel filling are the most serious.

Disease cycle

The fungus overwinters in barley straw and stubble, in the soil, or on the seed. Spores are produced on barley debris in the spring and are dispersed by wind and rain. Barley seedlings may become infected from incolum on the seed or in the soil.

Temperatures above 20C and moist humid conditions within the crop canopy favour spot blotch development. Conducive weather conditions may favour successive production of new spores and lesions leading to rapid disease development during the growing season.

Yield loss

The disease may be particularly damaging in the Upper Midwest of the United States. Yield losses of 10-30% may be occur when weather conditions are conducive to disease development.Yield loss]

Management

The disease is managed used resistant varieties, clean seed, seed treatments, foliar fungicide and rotation to non-cereal crops.

External links

Extension publications

[http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm2432 Spot blotch (Canada: Alberta)]
[http://www.darcof.dk/enews/mar05/blotch.html Spot blotch (Denmark)]
[http://www.ag.ndsu.edu/pubs/plantsci/smgrains/pp894w.htm Spot blotch (US: North Dakota)]
[http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=114 Spot blotch (US: Oregon)]

Research articles

cite journal
last = Clark
first = R.V.
title = Yield losses in barley cultivars caused by spot blotch
journal = CJPP
volume = 1
pages = 113–117
date = 1979
url = http://www.cps-scp.ca/download/cjpp-archive/Vol1/CJPP1(2)113-117(1979).pdf

cite journal
last = Clay
first = R.P.
coauthors = C.W. Bergmann, M.S. Fuller
title = Isolation and characterization of an endopolygalacturonase from Cochliobolus sativus and a cytological study of fungal penetration of barley
journal = Phytopathology
volume = 87
pages = 1148–1159
date = 1997
url = http://www.apsnet.org/phyto/PDFS/1997/0828-02R.PDF
doi = 10.1094/PHYTO.1997.87.11.1148

cite journal
last = Duczek
first = L.J.
title = Infection of wheat and barley by Bipolaris sorokiniana during early growth stages and effects on leaf area
journal = CJPP
volume = 19
pages = 293–296
date = 1997
url = http://www.cps-scp.ca/download/cjpp-archive/Vol19/CJPP19(3)293-296(1997).pdf

cite journal
last = Eng-Chong
first = P.
coauthors = R.-L. Pelletier, H.R. Klinck
title = Seedling blight, spot blotch, and common root rot in Quebec and their effect on grain yield in barley
journal = CJPP
volume = 7
pages = 395–401
date = 1985
url = http://www.cps-scp.ca/download/cjpp-archive/Vol7/CJPP7(4)395-401(1985).pdf

cite journal
last = Fetch, Jr.
first = T.G.
coauthors = B.J. Steffenson
title = Identification of Cochliobolus sativus isolates expressing differential virulence on two-row barley genotypes from North Dakota
journal = CJPP
volume = 16
pages = 202–206
date = 1994
url = http://www.cps-scp.ca/download/cjpp-archive/Vol16/CJPP16(3)202-206(1994).pdf

cite journal
last = Fetch, Jr.
first = T. G.
coauthors = B.J. Steffenson
title = Rating scales for assessing infection responses of barley infected with Cochliobolus sativus
journal = Plant Dis.
volume = 83
pages = 213–217
date = 1999
url = http://www.apsnet.org/pd/pdfs/1999/0122-01S.PDF
doi = 10.1094/PDIS.1999.83.3.213

cite journal
last = Johnston
first = H.W.
coauthors = J.A. Macleod
title = Response of spring barley to fungicides, plant growth regulators, and supplemental nitrogen
journal = CJPP
volume = 9
pages = 255–259
date = 1987
url = http://www.cps-scp.ca/download/cjpp-archive/Vol9/CJPP9(3)255-259(1987).pdf

cite journal
last = Kutcher
first = H.R.
coauthors = K.L. Bailey, B.G. Rossnagel, W.G. Legge
title = Heritability of common root rot and spot blotch resistance in barley
journal = CJPP
volume = 16
pages = 287–294
date = 1994
url = http://www.cps-scp.ca/download/cjpp-archive/Vol16/CJPP16(4)287-294(1994).pdf

cite journal
last = Martin
first = R.A.
coauthors = J.B. Sanderson
title = Yield of barley in response to propiconazole
journal = CJPP
volume = 10
pages = 66–72
date = 1988
url = http://www.cps-scp.ca/download/cjpp-archive/Vol10/CJPP10(1)66-72(1988).pdf

cite journal
last = Pringle
first = R.B.
title = Nonspecific adhesion of Bipolaris sorokiniana sporelings
journal = CJPP
volume = 3
pages = 9–11
date = 1981
url = http://www.cps-scp.ca/download/cjpp-archive/Vol3/CJPP3(1)9-11(1981).pdf

cite journal
last = Stevenson
first = I.L.
title = Timing and nature of seed infection of barley by Cochiliobolus sativus
journal = CJPP
volume = 3
pages = 76–85
date = 1981
url = http://www.cps-scp.ca/download/cjpp-archive/Vol3/CJPP3(2)76-85(1981).pdf

cite journal
last = Valjavec-Gratian
first = M.
coauthors = B.J. Steffenson
title = Pathotypes of Cochliobolus sativus on barley in North Dakota
journal = Plant Dis.
volume = 81
pages = 1275–1278
date = 1997
url = http://www.apsnet.org/pd/PDFS/1997/0919-01R.PDF
doi = 10.1094/PDIS.1997.81.11.1275

cite journal
last = Valjavec-Gratian
first = M.
coauthors = B.J. Steffenson
title = Genetics of virulence in Cochliobolus sativus and resistance in barley
journal = Phytopathology
volume = 87
pages = 1140–1143
date = 1997
url = http://www.apsnet.org/phyto/PDFS/1997/0919-01R.PDF
doi = 10.1094/PHYTO.1997.87.11.1140

cite journal
last = Zhong
first = S.
coauthors = B.J. Steffenson
title = Virulence and molecular diversity in Cochliobolus sativus
journal = Phytopathology
volume = 91
pages = 469–476
date = 2001
url = http://www.apsnet.org/phyto/pdfs/2001/0308-01R.pdf
doi = 10.1094/PHYTO.2001.91.5.469

References