Scald (barley)

Scald (barley)

Scald is common disease of barley in temperate regions. It is caused by the fungus Rhynchosporium secalis and can cause significant yield losses in cooler, wet seasons.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

Scald is a foliar disease of barley affecting the leaves and sheaths of the plant, however, lesions may also occur on coleoptiles, glumes, floral bracts and awns. Initial sympotms are oval, water-soaked, grayish-green spots, 1.0-1.5 cm long. As the disease develops, the centers of the lesions dry and bleach, becoming light gray, tan, or white. with a dark brown margin. The lesions are not delimited by the leaf veins and often coalesce.

Disease cycle

The fungus can infect and survive in barley seed. It exists as mycelium in the pericarp and hull of infected seeds. Infection of the coleoptile occurs as it emerges from the embryo. Optimal infections occurs at soil temperatures of 16C. At soil temperatures of 22C or higher, very little infection occurs.

In spring cropping systems, the fungus overwinters on the crop debris and stubble of previous diseased barley crops. The fungus produces abundant conidia on wet lesions during cool, damp weather after the leaf tissue has become necrotic. Conidia, spread by wind and splashing rain, infect young leaves of spring- planted grain. Optimum temperatures for sporulation and infection range from 10-18C. Hot, dry weather reduces the rate of disease development.

Geographical distribution and economic importance

The disease is economically important barley disease in Europe, North America and Australia. It has been reported from South America, Africa, the Middle east, Japan and Korea. Yield losses as high as 35-40% have been reported, however, losses of 1-10% are more common. Yield loss is primarily due to reduced kernel weight, but both kernels per head and number of heads per plant may also been affected.

In the wetter areas of the United Kingdom, scald is the most damaging disease of barley, affecting both spring and winter crops. [http://www.sac.ac.uk/consultancy/cropclinic/clinic/diseases/rhynchosporium Europe: Scotland] ] . In the Victoria area of Australia, scald is widespread in barley crops in most seasons, but its severity varies greatly from crop to crop and between seasons. In Victoria, scald causes annual average yield losses of 10-20%, with individual losses as high as 45% in susceptible varieties. [http://www.dpi.vic.gov.au/dpi/nreninf.nsf/childdocs/-22C871BE2A0105794A2568B30004D413-3C5B474B480825C8CA256BC700824574-78F1BBD6496F89034A256DEA00274EEC-491BE1EC936D69A3CA256C170004772F?open Australia] ] In Canada, yield losses in Alberta have been calculated at 2.4 per cent, although losses in particular fields may exceed 25 per cent. Losses are due to a decrease in photosynthetic area on the flag and second leaves resulting in reduced seed weight. [http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm2427 Alberta yield losses] ]

Management

Management of the disease involves the use of clean and/or treated seeds, resistant cultivars, crop rotation, residue management, and foliar fungicides.

Resistant cultivars

Cultivars with scald resistance are available in all major barley growing areas. The level of resistance occurs along a spectrum and the degree of resistance that is required to effectively control the disease will depend on the region where it is grown, cropping practices that reduce initial disease inoculum, wetter conditions and fungal pathotypes.

Fungicides

Foliar fungicides can be used to effectively control disease development. Product selection, application rates and timing, depend upon numerous factors.

The availability of fungicides as a management tool depends on whether the product has been evaluated and registered for use in a specific country or region.

Foliar fungicides: azoxystrobin1, bromuconazole1, cyproconazole1, epoxiconazole1, fluquinconazole1, flusilazole1, propiconazole1, 2, 3, prochloraz1, pyraclostrobin2,tebuconazole1

Seed treatment fungicides: triadimenol2

1. [http://209.85.165.104/search?q=cache:odp29TY_Ee8J:archives.eppo.org/EPPOStandards/PP2_GPP/pp2-11-e.doc+barley+diseases+eppo&hl=en&ct=clnk&cd=4&gl=us EPPO - Europe]
2. [http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm2427 Canada: Alberta]
3. [http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=112 US: Oregon]

Fungicide resistance

In the United Kingdom, there are issues concerning MBC fungicides and some of the triazole fungicides (e.g. flusilazole and epoxiconazole). To date there are no issues with strobilruin fungicides (QoI fungicides), but the situation is being monitored closely. There are currently no issues concerning chlorothalonil, cyprodinil or the morpholines.Fungicide resistance]

External links

Extension publications

* [http://www.dpi.vic.gov.au/dpi/nreninf.nsf/childdocs/-22C871BE2A0105794A2568B30004D413-3C5B474B480825C8CA256BC700824574-78F1BBD6496F89034A256DEA00274EEC-491BE1EC936D69A3CA256C170004772F?open Australia]
* [http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm2427 Canada: Alberta]
* [http://209.85.165.104/search?q=cache:odp29TY_Ee8J:archives.eppo.org/EPPOStandards/PP2_GPP/pp2-11-e.doc+barley+diseases+eppo&hl=en&ct=clnk&cd=4&gl=us EPPO - Europe]
* [http://www.sac.ac.uk/consultancy/cropclinic/clinic/diseases/rhynchosporium Europe: Scotland]
* [http://www.ag.ndsu.edu/pubs/plantsci/smgrains/pp894w.htm US: North Dakota]
* [http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=112 US: Oregon]
* [http://pnw-ag.wsu.edu/smallgrains/Barleyscald.html US: Washington]

Research articles

cite journal
last = Abang
first = M.M.
coauthors = M. Baum, S. Ceccarelli, S. Grando, C.C. Linde, A. Yahyaoui, J. Zhan, B.A. McDonald.
title = Differential selection on Rhynchosporium secalis during parasitic and saprophytic phases in the barley scald disease cycle
journal = Phytopathology
volume = 96
pages = 1214–1222
date = 2006
url = http://www.apsnet.org/phyto/search/2006/phyto-96-1214.asp
doi = 10.1094/PHYTO-96-1214

cite journal
last = Bjørnstad
first = Å.
coauthors = V. Patil, A. Tekauz, A.G. Marøy, H. Skinnes, A. Jensen, H. Magnus, J. MacKey
title = Resistance to scald (Rhynchosporium secalis) in barley (Hordeum vulgare) studied by near-isogenic lines: I. Markers and differential isolates.
journal = Phytopathology
volume = 92
pages = 710–720
date = 2002
url = http://www.apsnet.org/phyto/pdfs/2002/0429-01R.pdf
doi = 10.1094/PHYTO.2002.92.7.710

cite journal
last = Fountaine
first = J.M.
coauthors = M.W. Shaw, B. Napier, E. Ward, B.A. Fraaije.
title = Application of Real-Time and Multiplex Polymerase Chain Reaction Assays to Study Leaf Blotch Epidemics in Barley
journal = Phytopathology
volume = 97
pages = 297–303
date = 2007
url = http://www.apsnet.org/phyto/search/2007/phyto-97-3-0297.asp
doi = 10.1094/PHYTO-97-3-0297

cite journal
last = Goodwin
first = S.B.
coauthors = R.K. Webster, R.W. Allard
title = Evidence for Mutation and Migration as Sources of Genetic Variation in Populations of Rhynchosporium secalis
journal = Phytopathology
volume = 84
pages = 1047–1053
date = 1994
url = http://www.apsnet.org/phyto/PDFS/1994/Phyto84n10_1047.PDF
doi = 10.1094/Phyto-84-1047

cite journal
last = Hahn
first = M.
title = Cultivar-specific elicitation of barley defense reactions by the phytotoxic peptide NIP1 from Rhynchosporium secalis
journal = MPMI
volume = 6
pages = 745–754
date = 1993
url = http://www.apsnet.org/mpmi/pdfs/1993/Microbe06_745.pdf

cite journal
last = Lee
first = H. K.
coauthors = J.P. Tewari, T.K. Turkington
title = A PCR-based assay to detect Rhynchosporium secalis in barley seed
journal = Plant Dis.
volume = 85
pages = 220–225
date = 2000
url = http://www.apsnet.org/pd/pdfs/2000/1206-02R.pdf
doi = 10.1094/PDIS.2001.85.2.220

cite journal
last = Lyngsjorgensen
first = H.J.
coauthors = V. Smedegaard-Petersen
title = Pathogenic variation of Rhynchosporium secalis in Denmark and sources of resistance in barley
journal = Plant Dis.
volume = 79
pages = 297–301
date = 1995
url = http://www.apsnet.org/pd/PDFS/1995/PlantDisease79n03_297.PDF

cite journal
last = McDonald
first = B.A.
coauthors = J. Zhan, J.J. Burdon
title = Genetic structure of Rhynchosporium secalis in Australia
journal = Phytopathology
volume = 89
pages = 639–645
date = 1999
url = http://www.apsnet.org/phyto/PDFS/1999/0614-02R.PDF
doi = 10.1094/PHYTO.1999.89.8.639

cite journal
last = Salamati
first = S.
coauthors = J. Zhan, J.J. Burdon, B.A. McDonald
title = The genetic structure of field populations of Rhynchosporium secalis from three continents suggests moderate gene flow and regular recombination
journal = Phytopathology
volume = 90
pages = 901–908
date = 2000
url = http://www.apsnet.org/phyto/pdfs/2000/0612-01R.PDF
doi = 10.1094/PHYTO.2000.90.8.901

cite journal
last = Steiner-Lange
first = S.
coauthors = A. Fischer, A. Boettcher, I. Rouhara, H. Liedgens, E. Schmelzer, W. Knogge
title = Differential defense reactions in leaf tissues of barley in response to infection by Rhynchosporium secalis and to treatment with a fungal avirulence gene product
journal = MPMI
volume = 16
pages = 893–902
date = 2003
url = http://www.apsnet.org/mpmi/pdfs/2003/0729-01R.pdf

cite journal
last = Schürch
first = S.
coauthors = C.C. Linde, W. Knogge, L.F. Jackson, B.A. McDonald
title = Molecular population genetic analysis differentiates two virulence mechanisms of the fungal avirulence gene NIP1
journal = MPMI
volume = 17
pages = 1114–1125
date = 2004
url = http://www.apsnet.org/mpmi/pdfs/2004/0719-01R.pdf

cite journal
last = Tekauz
first = A.
title = Pathogenic variation in Rhynchosporium secalis on barley in Canada
journal = CJPP
volume = 13
pages = 298–304
date = 1991
url = http://www.cps-scp.ca/download/cjpp-archive/Vol13/CJPP13(4)298-304(1991).pdf

cite journal
last = Xi
first = K.
coauthors = P.A. Burnett, J.P. Tewari, M.H. Chen, T.K. Turkington, J.H. Helm
title = Histopathological study of barley cultivars resistant and susceptible to Rhynchosporium secalis
journal = Phytopathology
volume = 90
pages = 94–102
date = 1999
url = http://www.apsnet.org/phyto/pdfs/1999/1122-01R.pdf
doi = 10.1094/PHYTO.2000.90.1.94

cite journal
last = Xi
first = K.
coauthors = T.K. Turkington, J.H. Helm, C. Bos
title = Pathogenic variation of Rhynchosporium secalis in Alberta
journal = Can. J. Plant Pathol.
volume = 24
pages = 176–183
date = 2002
url = http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?_handler_=HandleInitialGet&journal=tcjpp&volume=24&articleFile=k02-113.pdf

cite journal
last = Xi
first = K.
coauthors = A.G. Xue, P.A. Burnett, J.H. Helm, T.K. Turkington
title = Quantitative resistance of barley cultivars to Rhynchosporium secalis
journal = CJPP
volume = 22
pages = 217–223
date = 2000
url = http://www.cps-scp.ca/download/cjpp-archive/Vol22/CJPP22(3)217-223(2000).pdf

cite journal
last = Xi
first = K
coauthors = T.K. Turkington, J.H. Helm, K.G. Briggs, J.P. Tewari, T. Ferguson, P.D. Kharbanda
title = Distribution of pathotypes of Rhynchosporium secalis and cultivar reaction on barley in Alberta
journal = Plant Dis.
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pages = 391–396
date = 2003
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doi = 10.1094/PDIS.2003.87.4.391

cite journal
last = Xue
first = A.G.
coauthors = P.A. Burnett, J. Helm, B.G. Rossnagel
title = Variation in seedling and adult-plant resistance to Rhynchosporium secalis in barley
journal = CVJPP
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pages = 46–48
date = 1995
url = http://www.cps-scp.ca/download/cjpp-archive/Vol17/CJPP17(1)46-48(1995).pdf

cite journal
last = Xue
first = A.G.
coauthors = R. Hall
title = Components of parasitic fitness in Rhynchosporium secalis and quantitative resistance to scald in barley as determined with a dome inoculation chamber
journal = CJPP
volume = 13
pages = 19–25
date = 1991
url = http://www.cps-scp.ca/download/cjpp-archive/Vol13/CJPP13(1)19-25(1991).pdf

cite journal
last = Zareie
first = Reza
coauthors = D.L. Melanson, P.J. Murphy
title = Isolation of fungal cell wall degrading proteins from barley (Hordeum vulgare L.) leaves infected with Rhynchosporium secalis
journal = MPMI
volume = 15
pages = 1031–1039
date = 2002
url = http://www.apsnet.org/mpmi/pdfs/2002/0803-01R.pdf

References


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