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Date: December 2013
Source: Summa Phytopathologica Brazil [in Spanish, machine trans., summ., Mod.DHA, edited] <http://dx.doi.org/10.1590/S0100-54052013000400014>
[Ref: Cundom MA, Cabrera MG, Gutierrez SA: _Bipolaris sorghicola_: an emerging pathogen in sorghum crops in NE Argentina. Summa phytopathol.
2013; 39(4): 295-6; DOI: 10.1590/S0100-54052013000400014]
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During a disease survey of sorghum crops (_Sorghum bicolor_) in the Northeast region of Argentina, plants with necrotic lesions on leaves were observed. Symptoms consisted of elliptical, dark purplish spots parallel to leaf ribs measuring 0.5 to 1.5 cm in length on average, resulting in death of affected leaves. These symptoms were not observed previously in sorghum in this region.
Based on morphological and cultural characteristics, the causal agent was identified as _Bipolaris sorghicola_. This is thought to be the 1st report of _B. sorghicola_ on sorghum crops in the Northeast region of Argentina.
The pathogen has a short incubation period and can cause severe infections. The disease should be monitored carefully because it is potentially a serious problem which can turn into an epidemic.
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[Target spot of sorghum is caused by the fungus _Bipolaris sorghicola_. Other than grain sorghum (_S. bicolor_), it can also affect other species in the genus, including Johnson grass (_S.
halepense_) and Sudangrass (_Sorghum_ hybrid). Symptoms may include oval purplish or yellowish leaf spots, depending on host species and cultivar, followed by leaf necrosis and death of the affected leaves.
The disease reduces plant vigour and affects grain yield and quality.
It is favoured by warm temperatures.
Spores are carried on seed and other plant parts. Sorghum grasses may serve as pathogen reservoirs for grain sorghum crops. Disease management may include fungicide sprays, seed treatments (hot water, fungicides), removal of pathogen reservoirs, crop rotation with non-hosts, and use of resistant crop varieties.
Maps
Argentina:
<http://media.maps.com/magellan/Images/ARGENT-W1.gif> and <http://healthmap.org/r/1yJb> Provinces and regions of Argentina:
<http://www.zonu.com/argentina_maps/Argentina_Regions_Map_2.htm>
South America, overview:
<http://www.worldatlas.com/webimage/countrys/samerica/printpage/samainp.htm>
Pictures of target spot symptoms on sorghum:
<http://img.springerimages.com/Images/Springer/JOU=00122/VOL=2011.123/ISU=1/ART=1572/
MediaObjects/WATER_122_2011_1572_Fig1_HTML.jpg>
and
<http://www.agromanual.cz/userfiles/image/clanky/kuthan_1_2012_choroby_ciroku/08.jpg>
Links
Information on sorghum target spot via:
<http://extension.missouri.edu/publications/DisplayPrinterFriendlyPub.aspx?P=G4356>
and
<http://www.naro.affrc.go.jp/org/nilgs/diseases/contents/de5.htm>,
and
<http://www.agromanual.cz/cz/clanky/ochrana-rostlin-a-pestovani/choroby/choroby-ciroku.html>
(in Czech)
_B. sorghicola_ taxonomy:
<http://www.indexfungorum.org/names/NamesRecord.asp?RecordID=108722>
- Mod.DHA]
[See Also:
2013
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Fungal diseases, rice - USA, India 20130905.1926343
2012
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Multiple diseases, rice - India: (AR) 20120911.1287862
2009
----
Spot blotch, wheat - Pakistan: (PB, SD) 20090606.2094
2005
----
Wheat stem-base disease - Iran (Hamadan): 1st report 20050430.1203]