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International Society for Infectious Diseases <http://www.isid.org>

Date: 19 September 2008
Source: Reuters India [edited]
<http://in.reuters.com/article/topNews/idINIndia-35560020080919>

Rains bring disease threat to Punjab cotton, rice crops

Unseasonably heavy rains in northwestern India have damaged the cotton crop in some areas and exposed paddy to plant diseases, farmers and scientists said.

Bacterial blight, a disease that dries up a plant's leaves, has been reported in parts of Punjab and the problem could worsen if water is not quickly drained, they said. Punjab accounts for 11 percent of India's rice output.

A farm scientist at the Punjab Agricultural University (PAU) in Ludhiana, Chander Mohan, said blight can reduce yields but added the disease was not so far widespread. "Depending on the severity of disease, yield losses could be around 10 percent in paddy and 5-30 percent in basmati and other superior varieties."

Light rains are forecast in Punjab in the next 3 days. "High temperature and humidity may hasten the spread of blight. However, if the weather clears up in next 3-4 days, the incidence of disease will go down," KK Gill, from PAU's Department of Agricultural Meteorology, said.

[Byline: Ikhhlaq Singh Aujla]

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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. In Asia, millions of hectares of rice paddies are severely affected every year with reported yield losses of up to 60 percent. The bacterium is short-lived in soil and suspected to be seed-borne, and is spread mainly by windblown rain and mechanical means. Disease management includes phytosanitation, cultural measures (removal of weedy reservoirs), and use of resistant crop varieties. For more information on BLB please see previous ProMED-mail post no. 20080416.1364 and links below.

Maps
India:
<http://www.globalsecurity.org/military/world/india/images/IndiaMap_tourism.gif>
Punjab:
<http://healthmap.org/promed?v=31,76,5>
Punjab districts:
<http://www.mapsofindia.com/maps/punjab/punjab-district.htm>

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>

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>
Details of rice varieties:
<http://dacnet.nic.in/rice/Rice%20Varieties%20-%2008.htm>.  - Mod.DHA]