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: Tue 28 Apr 2009
Source: AgWeb [edited]
<http://www.agweb.com/Blogs/BlogPost.aspx?src=SouthernView&PID=a4934cc5-1f5f-4cb1-9dd7-a5bc272ace41>
Asian rust spots increase in Brazil
Mato Grosso [MT] state is reaching 100 percent of soybeans
harvested, and registers 9 percent more rust foci than for the
last crop. In the whole of Brazil, so far there were 2810 sites
with Asian rust registered. This is 34 percent more than last
year.
In MT the number of samples submitted to laboratories increased
by 70 percent, and in the whole country the monitoring program
was also intensified on the same scale.
But the Ag Eng. Carlos Bortolini Jr warns the rust is getting
more resistant each year, and so producers need to expend more
investments in fungicide. In his point of view, Asian rust must
be handled as an epidemic to be defeated.
--
Communicated by:
ProMED-mail
<promed@promedmail.org>
[Leaf rust (also called soybean rust, Asian rust) caused by the
fungus _Phakopsora pachyrhizi_ can result in yield losses of
soybean crops of up to 70 percent. It is widespread in Asia and
Africa and spreading in the Americas, but data are lacking on
its establishment in Europe. Besides soybean, over 30 other
species in the family of _Fabaceae_, including kudzu (_Pueraria
lobata_), can also be affected and may serve as pathogen
reservoirs.
Spores are spread locally by splashing rain, or by wind over
long distances. Several epidemic cycles may occur in one
cropping season. Fungicides may be used in disease management,
but timing of applications is considered important. Partially
resistant soybean lines are available. However, new fungal
strains with increased virulence and fungicide resistances are
emerging, as is being reported above from Brazil.
While the related species _P. meibomiae_ is also found in South
America and the Caribbean causing similar symptoms, this species
is less virulent and is not referred to as 'Asian' rust. The
item above refers to _P. pachyrhizi_ which has been established
in Brazil since 2002.
Maps of Brazil
<http://en.18dao.net/images/9/96/Map-Brazil.jpg>
and <http://healthmap.org/r/008S>
Pictures
Leaf rust on soybean:
<http://www.ent.iastate.edu/images/plantpath/soybean/asianrust/asian_soyrust_lesions.jpg>,
<http://www.state.nj.us/agriculture/plant/soybeanrust.jpg>
and
<http://www.wbhm.org/pics/features/soybean-icon.jpg>
Electron microscopy of leaf rust spores:
<http://www.wbhm.org/pics/features/soybean-spores.jpg>
Links
Information on soybean rust:
<http://www.eppo.org/QUARANTINE/Alert_List/fungi/PHAKPA.htm>,
<http://ohioline.osu.edu/ac-fact/0048.html>,
and
<http://nt.ars-grin.gov/taxadescriptions/factsheets/index.cfm?thisapp=Phakopsorapachyrhizi>
Disease history and background (with pictures):
<http://www.apsnet.org/online/feature/rust/>
History and evolution in Brazil:
<http://www.scielo.br/scielo.php?pid=S1415-47572008000500020&script=sci_arttext>
and
<http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=157028>
_P. pachyrhizi_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=121037>.
- Mod.DHA]
[see also
in the
archive:
Leaf rust, soybean - USA: update 20090428.1594
Leaf rust, soybean - Australia: (NSW) alert 20090407.1351
2008
----
Soybean diseases - USA: (LA) 20081012.3231
Asian soybean rust - USA, Mexico: update 20080928.3070
2007
----
Asian soybean rust - USA: 2007 final report 20071230.4184
Asian soybean rust - Canada: 1st report, (ON) 20071120.3751
Asian soybean rust - Congo DR: 1st report 20070917.3086
Asian soybean rust - Ghana: 1st report 20070820.2710
2006
----
Soybean rust, Asian strain - Brazil 20060611.1628
Soybean rust - Mexico: 1st report 20060219.0546
2005
----
Soybean rust, Asian strain - Uruguay 20050819.2435
Soybean rust - Argentina (Santa Fe)(02) 20050816.2397
Soybean rust, Asian strain - Argentina (Santa Fe) 20050617.1715
Soybean rust, Asian strain - Americas: alert 20050528.1476
Soybean rust, Asian strain - Argentina 20050119.0185
2004
----
Soybean rust, Asian strain - Brazil 20041222.3374
Soybean rust, Asian strain - Brazil (multistate) 20041209.3266
Soybean rust, Asian strain - Brazil (PR) 20041129.3186
Soybean rust - USA: 1st report 20041110.304
Soybean rust - Colombia (Cali) 20040827.2393
2003
----
Phakopsora pachyrhizi, soybean - Brazil 20031119.2873
Soybean rust - Brazil 20030426.1022
Soybean rust - Brazil (Mato Grosso & Bahia) 20030415.0917
Soybean rust - Brazil (Sao Paulo State) 20030124.0214
and older items in the archives]