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: Fri 24 Mar 2017
Source: Page One [edited]
<http://pageone.ph/php17-87m-initial-damage-reported-in-samar-rice-pest-disease-infestation/>
Damages have been incurred from widespread pest and disease infestation in Northern Samar and Eastern Samar provinces. The Department of Agriculture said there is 4000 hectares [9884 acres of] rice farms reportedly plagued by the destructive bacterial leaf blight (BLB) [and] brown plant hoppers.
The response team has validated 648 hectares [1601 acres] affecting 745 farmers. BLB has been causing havoc in Northern Samar while plant hoppers have been attacking Eastern Samar. "The DA is now seeking the help of the municipal agriculture officers as well as the farmers to adopt mitigating measures."
[BLB] infestations have been recorded in Northern Samar since early January [2017]. The DA advised affected farmers to continue monitoring rice fields [and] immediate harvesting of the remaining unaffected matured crops, among others.
--
Communicated by: ProMED-mail <promed@promedmail.org>
[Bacterial leaf blight (BLB) of rice is caused by _Xanthomonas oryzae_ pv. _oryzae_. In Asia, millions of hectares of rice paddies are severely affected every year, with reported yield losses of up to 60 per cent. 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 favoured 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 seed borne 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 or by high insect activity).
Disease management usually 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. Control of insect populations by insecticides may help reduce the unspecific spread of bacteria via their scratching and sucking wounds. Antibacterial sprays containing antibiotics are rarely used because they often provide little benefit, and agricultural application of antibiotics is strictly regulated in most countries. The related _X. oryzae_ pv. _oryzicola_ causes bacterial leaf streak of rice.
The brown planthopper (BPH; _Nilaparvata lugens_) is one of the worst pests of rice in the Australasian and Pacific Island region. It is a vector of viruses that cause serious diseases of the crop (such as _Rice grassy stunt virus_ and _Rice ragged stunt virus_; for example, see ProMED-mail posts http://promedmail.org/post/20100628.2155 and http://promedmail.org/post/20100409.1145). High vector populations are often associated with outbreaks of these viruses. In its own right, BPH causes yellowing, browning and drying of plants ('hopper burn') and leaves small injuries exposing the plant to fungal and bacterial infections.
Maps
Philippines:
<http://www.worldatlas.com/webimage/countrys/asia/lgcolor/phcolor.htm>
and
<http://healthmap.org/promed/p/15501>
Philippine provinces and regions:
<https://www.worldofmaps.net/typo3temp/images/provinzen-philippinen.png>
Pictures
BLB symptoms on rice leaves:
<http://agropedia.iitk.ac.in/sites/default/files/uas%20raichur/diseases%20of%20paddy/blb00.jpg>
and
<http://www.knowledgebank.irri.org/images/stories/bacterial-leaf-blight-4.JPG>
BLB affected rice plants:
<http://www.apsnet.org/edcenter/K-12/TeachersGuide/PlantBiotechnology/Article%20Images/fig34.jpg>,
<http://www.invasive.org/images/768x512/0162039.jpg>, and <http://www.invasive.org/images/768x512/0162037.jpg>
BLB affected rice field:
<http://www.apsnet.org/edcenter/advanced/topics/EcologyAndEpidemiologyInR/ModelingDispersalGradients/PublishingImages/BacterialBlight.jpg>
Droplets of bacterial exudate on leaf:
<http://www.invasive.org/images/768x512/0162038.jpg>
Brown rice hoppers:
<http://www.dpvweb.net/dpv/showfig.php?dpvno=320&figno=03> and <http://www.saigon-gpdaily.com.vn/dataimages/original/2010/02/images178238_Raynau.jpg>
Links
BLB of rice, disease information:
<http://www.knowledgebank.irri.org/decision-tools/rice-doctor/rice-doctor-fact-sheets/item/bacterial-blight>,
<http://www.cabi.org/isc/datasheet/56956> (with distribution map), <http://www.apsnet.org/publications/PlantDisease/BackIssues/Documents/1993Articles/PlantDisease77n01_5.pdf>,
and via
<http://www.oisat.org/pests/diseases/bacterial/bacterial_leaf_blight.html>
_X. oryzae_ pv. _oryzae_ taxonomy:
<http://www.uniprot.org/taxonomy/64187>
Brown planthopper information:
<http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/insects/item/planthopper>
(with pictures)
- Mod.DHA]
[See Also:
2016
----
Bacterial leaf blight, rice - India: (TN)
http://promedmail.org/post/20161228.4729157
Bacterial leaf blight, rice - Bangladesh: (RJ)
http://promedmail.org/post/20161101.4598659
Bacterial leaf blight, rice - Viet Nam: (Mekong Delta)
http://promedmail.org/post/20161014.4558824
Bacterial leaf blight, rice - Peru: (PI)
http://promedmail.org/post/20160405.4138616
2015
----
Bacterial leaf blight, rice - India: (TN)
http://promedmail.org/post/20151216.3868035
Bacterial leaf blight, rice - Bangladesh: (DA)
http://promedmail.org/post/20151009.3702001
Rice diseases - Malaysia: (western) emerging strains
http://promedmail.org/post/20150108.3080315
2014
----
Leaf blight & sheath rot, rice - Bangladesh: (RJ)
http://promedmail.org/post/20141017.2872718
Blast disease & bacterial blight, rice - Viet Nam: Mekong Delta, alert
http://promedmail.org/post/20140216.2282042
2012
----
Multiple diseases, rice - India: (AR)
http://promedmail.org/post/20120911.1287862
2010
----
Tungro, blast, bacterial blight, rice - India: (TN, OR)
http://promedmail.org/post/20100912.3299
Multiple disease, rice - Viet Nam (03)
http://promedmail.org/post/20100816.2835
Bacterial leaf blight, rice - India: (PB)
http://promedmail.org/post/20100726.2504
Ragged & grassy stunt viruses, rice - Thailand
http://promedmail.org/post/20100628.2155
Ragged & grassy stunt viruses, rice - Indonesia: (JB)
http://promedmail.org/post/20100409.1145
and older items in the archives]
Topics
Species
