A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>

Date: 9 October 2008

[1] Leaf & sheath blights, undiagnosed rot - Bangladesh
[2] Bacterial leaf blight - Pakistan: (Punjab), alert

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[1] Leaf & sheath blights, undiagnosed rot - Bangladesh
Date: 9 Oct 2008
Source: The Daily Star [edited]
<http://www.thedailystar.net/story.php?nid=57870>

The prospects of aman [a group of lowland rice varieties] paddy seem bleak in Kurigram and Lalmonirhat districts, as paddy plants on vast areas of land are affected by disease. Farmers and rice dealers in the 2 districts are anxious about a possible shortfall in aman production due to diseases and have expressed apprehension that the yield of aman paddy will decrease by almost half compared to last year [2007].

However, Agriculture Extension Department (AED) officials said the problem is not so grave and that only 5 percent of aman plants in the district were attacked by sheet blight and rot blight. Kurigram AED Deputy Director Mohshin Ali said, "Heavy rainfall in the last 5 days helped plants recover from the attack of leaf blight disease."

Several farmers of Lalmonirhat district, however, refuted the versions of AED officials and said about 60 percent of aman paddy plants in the district have been attacked with sheet blight and rot blight. "Aman paddy plants on 34 acres of my land were attacked with diseases," said Reazul Hoque Patwari of Lalmonirhat Sadar upazila [subdistrict]. Abdur Rahman of Rajarhat upazila in Kurigram district said aman paddy plants on 23 acres of his land are becoming yellowish. "I cultivated aman paddy on 20 acres of land. Plants got yellowish, and within 7 days they got dried. I can hardly get 20 maunds [ca. 746 kg] of paddy from the land," Motahar Hosen, a farmer of Lalmonirhat Sadar upazila said.

[Byline: Rafique Sarker]

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ProMED-mail <promed@promedmail.org>

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[2] Bacterial leaf blight - Pakistan: (Punjab), alert
Date: 11 Oct 2008
Source: The News International [edited]
<http://www.thenews.com.pk/daily_detail.asp?id=140300>

The Pest Warning Wing of the Agriculture Department, Punjab has warned growers of late-[planted] rice varieties to keep a vigil on their crop, as an attack of Bacterial Leaf Blight (BLB) might occur in some areas. Director General Pest Warning Dr Ijaz Parvaiz during a press briefing by the Punjab Agriculture Minister Malik Ahmad Ali Aulkah told newsmen that symptoms of the disease have been reported in 25 percent of areas of those regions where rice was sown late.

He said these areas include Hafizabad, Kamoke, Gujranwala, Sialkot, Okara, Nankana Sahib and Baddo Malhi. He said that the farmers should remain vigilant in these areas, and, as soon as a symptom of attack of the disease is found, they should spray copper-based fungicide on their crop to save it. He said that this disease appears in patches and could be controlled in its initial phase. "It is hard to control this disease at later stages," he said.

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[Bacterial leaf blight (BLB) of rice is caused by _Xanthomonas oryzae_ pv. _oryzae_ and has been reported from Asia, northern Australia, Africa, and the USA. The pathogen causes yellowing and drying of leaves, wilting of seedlings, and reduces yield. Yield losses of up to 60 percent have been reported in Asia. The bacterium is short-lived in soil and suspected to be seed-borne, and it is spread mainly by windblown rain and mechanical means. Disease management includes phytosanitation, cultural measures, and use of resistant crop varieties. For more information on BLB, please see previous ProMED-mail posts and links below.

Sheath blight (called "sheet blight" in report [1]) is caused by the fungus _Thanatephorus cucumeris_. Symptoms include expanding lesions on sheaths of leaves near the water line during the late tillering or early internode elongation growth stages. Infection spreads rapidly in the field by runner hyphae or plant-to-plant contact. Yield losses of up to 50 percent in highly susceptible cultivars result from poorly filled grain heads and from reduced plant vigour. Fungal sclerotia survive for long periods in the soil and float to the surface of flooded rice fields causing infection in the next crop.
The fungus can also attack a number of weed hosts, which can serve as reservoirs. No reliable source of genetic host resistance has been identified so far. Disease management includes cultural and phytosanitary techniques and foliar fungicides. For further information see ProMED-mail post 20070718.2300.

The name "rot blight" mentioned in item [1] is not commonly used for any rice disease, and it is not clear which pathogen is referred to.
We would be most grateful for information from anyone familiar with this term.

Maps
Bangladesh:
<http://www.lib.utexas.edu/maps/middle_east_and_asia/bangladesh_pol96.jpg>  and <http://healthmap.org/promed?v=23.8,90.3,5>
Bangladesh districts and cities:
<http://www.mapsofworld.com/bangladesh/bangladesh-political-map.html>
Pakistan:
<http://www.lib.utexas.edu/maps/middle_east_and_asia/pakistan_pol_2002.jpg>  and <http://healthmap.org/promed?v=30,69.4,5>

Pictures
BLB symptoms on leaves and whole plants via:
<http://www.invasive.org/browse/subject.cfm?sub=11182>
Comparison of BLB effect on resistant and susceptible cultivars:
<http://www.tari.gov.tw/tarie/photos/introduction/introduction_PPD_02.jpg>
Sheath blight symptoms:
<http://www.knowledgebank.irri.org/RiceDoctor/projectImages/image168.jpg>

Links
BLB disease information:
<http://www.knowledgebank.irri.org/RiceDoctor/Fact_Sheets/Diseases/Bacterial_Leaf_Blight.htm>
and
<http://www.oisat.org/pests/diseases/bacterial/bacterial_leaf_blight.html>
Comprehensive BLB review:
<http://www.ias.ac.in/currsci/dec101999/REVIEWARTICLE.PDF>
Genus _Xanthomonas_ taxonomy and species list:
<http://www.bacterio.cict.fr/xz/xanthomonas.html>
Sheath blight disease information:
<http://www.ncipm.org.in/sheath%20blight.htm>
_T. cucumeris_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=306777>
Information on rice diseases, including leaf and sheath blights:
<http://msucares.com/pubs/publications/p1840.htm>
Description of all major diseases of rice via:
<http://www.knowledgebank.irri.org/RiceDoctor/default.htm>
List of rice diseases and pathogens:
<http://www.apsnet.org/online/common/names/rice.asp>
Details of rice varieties:
<http://dacnet.nic.in/rice/Rice%20Varieties%20-%2008.htm>
- Mod.DHA]