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Date: Wed 18 Apr 2018 12:38:55 pm BST
Source: United News of Bangladesh (UNB) [edited]
< bangladesh-news/Rice-blast- hits-Boro-corps-in-Sirajganj/ 68519>

Farmers in Sirajganj district [Rajshahi division] are worried of
getting poor yield of [rice] crops due to blast attack, according to
the Department of Agricultural Extension (DAE). Some 20 000 hectares
[about 49 420 acres] have been affected by the disease in the last 3

DAE cancelled the leave of all staff in affected [areas] for bringing
the situation under control as well as to protect the paddy fields
from the attack.

DAE said farmers did not put fertiliser in a proper way. Besides, the
hot temperature in daylight and fall of the same at night has pushed
up the epidemic. [They] advised the farmers to spray medicines.
Communicated by:

[Rice blast is caused by the fungus _Pyricularia oryzae_ (previously
_Magnaporthe oryzae_). It is one of the most destructive diseases of
the crop worldwide, with potential yield losses of more than 50 per
cent. Symptoms include lesions on all parts of the shoot, as well as
stem rot and panicle blight. When nodes are infected, all plant parts
above the infection die and yield losses are severe. When infection
occurs at the seedling or tillering stages, plants are often
completely killed; infection late in the growth cycle generally leads
to less severe damage. Depending on which plant parts are affected,
the disease may manifest itself as leaf, collar, node, or neck blast.
More than 50 species of grasses and sedges can be affected by related
pathogens, but most strains isolated from rice can only infect a
limited number of cultivars.

The fungus also causes wheat blast (for example, see ProMED-mail posts 20170306.4883233 and 20170123.4784298). Although the pathogens
are currently classified as the same species, the wheat blast pathogen
is a distinct population (referred to as _P. oryzae_ Triticum
population) and does not cause disease in rice.

Symptom severity and spread of the blast fungus are influenced by
climatic conditions, including high humidity. The disease is also
favoured by high nitrogen levels (for example from fertilizers, as
mentioned above). The fungus is spread by infected plant debris,
mechanical means (including insect activity), water and wind. Disease
management may include fungicides and cultural practices but relies
mainly on resistant varieties. However, the fungus is highly variable
and this favours the emergence of new strains with increased
virulence. Use of certified clean seed is essential, and farm saved
seed poses a high risk of carry-over of the fungus to subsequent

< maps/bangladesh_map.jpg> and
< p/13276>
Bangladesh divisions:
Bangladesh districts:
< images/bangladesh-map.jpg>

Rice blast symptoms:
<http://www.knowledgebank. blast.jpg>
(different symptomatic forms) and
< raghava/rbpred/lesion.jpg>
Rice fields affected by blast:
< riceblog/blogfiles/22977_ original.jpg>,
< 01105768/b/1/Rice-Blast.jpg>, and
< images/imagethink/ imagethink1411/ imagethink141100067/33260576- rice-blast-Stock-Photo.jpg>
_P. oryzae_ culture:
< AP045K/a-culture-of-the-rice- blast-pathogen-pyricularia- grisea-on-a-pda-nutrient- AP045K.jpg>

Information on rice blast:
<http://www.knowledgebank. pest-management/diseases/item/ blast-leaf-collar>
(with pictures),
< diseases/fungal/rice_blast. html>,
< KnowledgeBank/Datasheet.aspx? dsid=46103>,
< raghava/rbpred/home.html>
Rice blast disease cycle:
< raghava/rbpred/cycle.jpg>
Impact of rice blast (and other fungal crop diseases):
<http://onlinelibrary.wiley. com/doi/10.1111/j.1364-3703. 2011.00783.x/full>
_P. oryzae_ taxonomy and synonyms:
< names/NamesRecord.asp? RecordID=224486>
<http://www.speciesfungorum. org/Names/SynSpecies.asp? RecordID=224486>
- Mod.DHA]

[See Also:
False smut & blast, rice - Bhutan, India 20171102.5419405
Blast disease, rice - India: (JK) 20170725.5202371
Blast disease, rice - Bangladesh 20170428.5000484
Blast & sheath blight, rice - Philippines: (II) 20160915.4489271
Blast disease, wheat & rice - Bangladesh 20160419.4168271
Blast disease, rice - India (02): (JK) origin 20160407.4145967
Blast disease, rice - India: (TN) 20160108.3918812
Neck blast, rice - India: (HR) 20151014.3713941
Blast disease, rice - Spain: (VC) 20150903.3620399
Sheath blight, rice - India: (PB) 20150831.3612426
Blast disease, rice - India: (TN) 20150128.3124545
Rice diseases - Malaysia: (western) emerging strains 20150108.3080315
Blast disease, rice - India: (GA) 20140417..2410154
Blast disease, rice - India: (TN) 20131231.2144256
Fungal diseases, rice - USA, India 20130905.1926343
and older items in the archives]
................................ lm
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