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 Jun 2009
Source: The Jakarta Post [edited]
<http://www.thejakartapost.com/news/2009/06/09/pests-diseases-attack-crops-central-java.html>

Pests and diseases have attacked at least 1600 hectares of rice fields in 4 regencies in southern Central Java [Jawa Tengah], causing major losses to local farmers.

Tri Gunawan, head of the Banyumas regency's Agricultural Pest and Disease Laboratory, said that farmers in Banyumas, Purbalingga, Cilacap, and Banjarnegara have been suffering from the attacks. "The biggest losses are caused by rats and bacterial blight disease. The other attacking pests are stemborer moths, rice ear bugs and mealy bugs," he said.

The laboratory also recorded a sharp increase in cases of bacterial blight disease, caused by high humidity during the dry season, which created perfect conditions for the bacteria to grow.

--
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ProMED-mail <promed@promedmail.org>

[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. In Asia, millions of hectares of rice paddies are severely affected every year, with reported yield losses of up to 60 percent. The pathogen causes yellowing and drying of leaves and wilting of seedlings. Blight lesions caused by severe strains elongate over the entire length of the flag leaf, giving a striped appearance. Severe strains may also affect panicles. Mild strains cause only small leaf lesions and may not lead to any detectable yield loss. Various saprophytic fungi may invade the lesions, contributing to the damage. Field patches infested with bacterial blight have a whitish, ragged appearance.

BLB is favored by rain, high levels of fertilizer, high humidity, standing pools of water, and warm temperatures. The bacterium is short-lived in soil and suspected to be seedborne but also to be short-lived in seeds. Grassy weeds, infected plant material such as rice stubble or ratoons, and contaminated irrigation systems are thought to be the primary pathogen reservoirs. The disease spreads by windblown rain and mechanical means (for example when transplanting seedlings), and the high insect activity reported above from Central Java may assist in the spread of the bacteria. Disease management includes phytosanitation (control of weed and volunteer rice reservoir hosts, removal of contaminated materials), cultural measures (optimal plant spacing and fertilizers), and use of resistant crop varieties.

Maps
Indonesia:
<http://images.nationmaster.com/images/motw/middle_east_and_asia/indonesia_rel98.jpg>
and
<http://healthmap.org/r/007g>
Indonesian provinces:
<http://www.indonesiamatters.com/images/indonesia-map.gif>

Pictures
BLB symptoms on rice leaves:
<http://www.invasive.org/images/768x512/5390468.jpg>
BLB affected rice plants:
<http://www.invasive.org/images/768x512/0162039.jpg>  and <http://www.invasive.org/images/768x512/0162037.jpg>
Droplets of bacterial exudate on leaf:
<http://www.invasive.org/images/768x512/0162038.jpg>
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>
Information on rice diseases, including BLB:
<http://msucares.com/pubs/publications/p1840.htm>
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>
- Mod.DHA]