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: Thu 16 Apr 2009
Source: The Guatemala Times [edited]
<http://www.guatemala-times.com/technology/science/1021-guatemalas-food-security-situation-according-to-mfews.html>

The food security situation in the country could be affected by an early annual season of food shortages in the west and east. For the north affected by floods, the case is different. After the losses of the 1st harvest, people sowed again hoping to harvest between February and March [2009]. However, the irregularity of rainfall and temperature changes at the end of the year [2008], as well as the humidity, caused the proliferation of fungi called Mancha de Asfalto (_Phyllachora maydis_ and _Monographella maydis_).

Damages due to the Mancha de Asfalto plague have not yet been assessed.
Although no large areas of affected crops were reported, a slight reduction in yields is expected, which would result in lower reserves in homes that were already experiencing problems of food availability.

Prices remaining stable during the next quarter would be expected if the damages by Mancha de Asfalto in the north do not affect the crop significantly. The government has a contingency plan for communities identified as high and very high risk. Maize is the main source of calories and protein in the Guatemalan diet.

--
communicated by:
ProMED-mail rapporteur Susan Baekeland

[Tar spot of maize is a disease complex, which has been known to cause serious yield losses in Central and South America. It is caused by the association of at least 3 fungal species: _Phyllachora maydis_, _Monographella maydis_, and _Coniothyrium phyllachorae_.

Of these, _P. maydis_ is usually the first to cause leaf lesions. While _M. maydis_ is a common benign saprophyte on leaf surfaces, it becomes highly virulent only in association with _P. maydis_ and forms necrotic rings around the _P. maydis_ lesions. _C. phyllachorae_ may be a hyperparasite of the other 2, but its role is not fully understood yet. Leaf lesions may coalesce causing blight and complete burning of the foliage. In addition,
characteristic black, shiny spots ('tar spots') are produced both within lesions and on other leaf areas. Affected ears have fewer kernels, which may germinate prematurely on the cob.

_P. maydis_ is an obligate parasite, its spores are spread by wind, and it produces a potent toxin killing plant tissue. The disease is favoured by cool, humid conditions. Disease management relies mainly on the use of
resistant maize varieties, however little is known about the genetics of tar spot resistance.

Contrary to the claims in the item above that maize yield may not be severely affected, outbreaks of Mancha de Asfalto have been reported earlier in the 2008/2009 season from the northern provinces of Guatemala with estimated crop losses of up to 75 per cent in Alta Verapaz and Quiche, and 50 per cent in Peten (see ProMED-mail post no. 20090220.0710).

Maps
Guatemala:
<http://www.lib.utexas.edu/maps/americas/guatemala_pol00.jpg>  and
<http://healthmap.org/r/009P>
Departments of Guatemala:
<http://www.guatemalaguides.com/about-guatemala/map-of-guatemala-by-departments.php#> 

Pictures of tar spot on maize
Progression of leaf symptoms:
<http://cril.cimmyt.org/gallery/main.php?g2_view=keyalbum.KeywordAlbum&g2_keyword=maize&g2_itemId=383>, 

<http://cril.cimmyt.org/gallery/main.php?g2_view=keyalbum.KeywordAlbum&g2_keyword=maize&g2_itemId=386>, 
and
<http://cril.cimmyt.org/gallery/main.php?g2_view=keyalbum.KeywordAlbum&g2_keyword=maize&g2_itemId=389> 

Affected ear:
<http://cril.cimmyt.org/gallery/main.php?g2_view=keyalbum.KeywordAlbum&g2_keyword=maize&g2_itemId=392> 

Links
Complete source document:
<http://www.fews.net/docs/Publications/Guatemala_FSU_2009_3_final_english.pdf>
Information on tar spot complex of maize:
<http://cat.inist.fr/?aModele=afficheN&cpsidt=3692273>,
<http://www.springerlink.com/content/g0wq78p421737137/>,
<http://cat.inist.fr/?aModele=afficheN&cpsidt=3371810>,
<http://cat.inist.fr/?aModele=afficheN&cpsidt=5320652>,  and
<http://www.informaworld.com/smpp/content~content=a905495708~db=all~order=page> 

Information on maize diseases, including tar spot (with pictures):
<http://www.cimmyt.org/english/docs/field_guides/maize/pdf/mzDis_foliar.pdf>
_Phyllachora maydis_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=167673>
_Monographella maydis_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=104487>
_Coniothyrium phyllachorae_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=178431>.   
Mod.DHA]

[see also in the archive:
Undiagnosed fungus, maize - Guatemala: RFI 20090220.0710
2008
---
Black cross, banana - Philippines: (DAV) 20081203.3795
2005
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Apple core rot - India (Himachal Pradesh) 20050808.2313]