Wednesday, May 26, 2010

Price of Coffee to Rise; Leaf Rust in Colombia

LEAF RUST, COFFEE - COLOMBIA: SPREAD
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A ProMED-mail post

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International Society for Infectious Diseases


Date: Wed 19 May 2010
Source: Dow Jones Newswires [edited]



'Rust disease' is latest threat to Colombian coffee crop
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The trees here [in Narino department], normally a lush green, are
yellow and spotty, as a virulent fungus compounds the woes of
Colombia's southern coffee-growing belt. Colombia is the world's
largest grower of high-quality arabica coffee beans. The provinces
accounting for about a third of that output are being hit by one of
the worst attacks of a fungal disease the region has ever seen.

This latest outbreak in southern Narino province is tied to a string
of weather problems caused by El Nino, which has warmed the Pacific
Ocean and led to unseasonal and excess rains followed by drought.
This appearance of rust disease follows a severe drought and an
outbreak of the broca pest [coffee berry borer] in another of the
country's main coffee-growing regions. Colombia's National Federation
of Coffee Growers, or Fedecafe, recently cut its forecast for output
in the first half of 2010.

[Byline: Maja Wallengren]

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Communicated by:
ProMED-mail


[Coffee leaf rust (CLR; also called orange rust) is caused by the
fungus _Hemileia vastatrix_, one of the most feared pathogens of the
crop. Of the 2 coffee species grown commercially, _Coffea arabica_
(arabica or highland coffee) and _Coffea canephora_ (robusta or
lowland coffee), it affects only arabica varieties and has completely
destroyed coffee industries in several countries. The disease is
characterised by yellow-orange powdery lesions on the underside of
leaves, where it attacks through stomata, but rarely occurs on stems
or fruit. CLR can lead to complete defoliation with death of the host
plant. Spores are spread by wind and rain.

Disease management relies mainly on multiple fungicide applications
during the rainy season. Rust-resistant cultivars exist, but the crop
is generally of poorer quality. More than 30 races of the fungus have
been detected, making it particularly difficult to establish durable
host resistance.

In Colombia, CLR outbreaks were reported in 2009 from several
departments including Caldas, Tolima, and Antioquia, but appears to
have spread further south. It has been said that severe CLR outbreaks
were last seen in the country over 25 years ago, and the possibility
of an emerging new, more aggressive fungal strain is being
considered. Cercospora leaf spot caused by the fungus _Mycosphaerella
coffeicola_ (ProMED-mail post 20100222.0595) and coffee berry borer
(_Hypothenemus hampei_; ProMED-mail post 20091008.3490) currently
exacerbate the situation in some parts of the country.

Maps
Colombia:
and

Colombia departments:

Early worldwide spread of coffee rust (pre-1990):


Pictures
CLR symptoms:
,
, and

Cercospora leaf spot and berry blotch:
,
, and

Coffee berry borer:

Berry borer damage on coffee beans:


Links
Coffee rust information and background:
,
, and

CLR resources:

_H. vastatrix_ taxonomy:

Information on cercospora leaf spot of coffee:
and via
,
, and

Coffee berry borer:
and

Arabica coffee varieties:
. - Mod.DHA]

[see also:
Coffee & cocoa diseases - Central Africa: update 20100421.1289
Cercospora leaf spot, coffee - Colombia: (QD) alert 20100222.0595
2009
----
Leaf rust, coffee - Colombia (02) 20091008.3490
Leaf rust, coffee - Colombia: (TO, CL) 20090225.0773
2008
----
Fungal diseases, coffee - East Africa 20081226.4072
2007
----
Leaf rust & berry disease, coffee - Kenya 20071108.3631]
...................................dha/mj/lm

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