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<http://www.promedmail.org>
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Date: 30 September 2008
Source: The Daily Star [edited]
<http://www.thedailystar.net/story.php?nid=57145>

Pest attack makes aman prospect bleak

Aman paddy [rice] fields in 5 northern districts have been affected by massive pest attack. Agriculture officials apprehend that the production may fall short of the target by around 5 lakh [500 000] tonnes in the 5 northern districts.

Fields have been attacked by leaf blight disease and pests including brown plant hopper. Pesticides available in markets are ineffective in controlling the disease and pest attack, farmers said, as they are adulterated. The disease and pest attack, which started about 2 weeks ago, have by now affected about 192 240 hectares [475 035 acres] in the districts of Dinajpur, Nilphamari, Joypurhat, Thakurgaon, and Panchagarh.

Vast areas of aman (lowland rice) fields have been attacked by pest and diseases also in Gaibandha. The fields are turning yellowish and the affected areas are increasing day-by-day, farmers and DAE [Department of Agricultural Extension] officials said. By now, fields in 17 unions in Gobindaganj Upazila have been affected. Agriculture Officers said the pest attack increased this year [2008] due to 'untimely rain'.

[Byline: Kongkon Karmaker]

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Communicated by:
ProMED-mail
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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 (control of weed and volunteer rice reservoir hosts, removal of contaminated materials), cultural measures (optimal plant spacing and fertilisers), and use of resistant crop varieties. For more information on BLB please see previous ProMED-mail posts and links below.

The types of rice grown in the region are 'aman' (lowland rice grown June to November), 'boro' (irrigated, cold-tolerant, cultivated during winter), and 'aus' (rainfed lowland or upland rice, broadcast and transplanted March to September). BLB affecting boro production was reported earlier this year (2008). Recent outbreaks of BLB have also been reported from India.

Brown planthoppers (_Nilaparvata lugens_) are one of the worst pests of rice in the Australasian and Pacific Island region. They are also the vector of _Rice ragged stunt virus_ (RRSV) and _Rice grassy stunt virus_ (RGSV), which can cause severe crop losses. Epidemics of these viruses are usually associated with high vector numbers (more information via ProMED-mail post no. 20080322.1093, see below).
Furthermore, leaf damage by insect activities also increases the risk of bacterial and fungal crop infections.

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>
Districts and cities:
<http://www.mapsofworld.com/bangladesh/bangladesh-political-map.html>

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>
Brown planthoppers:
<http://www.dpvweb.net/dpv/showfig.php?dpvno=320&figno=03>

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>
Information on rice diseases, including BLB:
<http://msucares.com/pubs/publications/p1840.htm>
Genus _Xanthomonas_ taxonomy and species list:
<http://www.bacterio.cict.fr/xz/xanthomonas.html>
Information on brown planthoppers:
<http://www.knowledgebank.irri.org/riceDoctor/Fact_Sheets/Pests/Planthopper.htm>
Details of rice varieties:
<http://dacnet.nic.in/rice/Rice%20Varieties%20-%2008.htm>.  - Mod.DHA]