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 24 Dec 2015
Source: Hivisasa [edited]
<http://www.hivisasa.com/kiambu/agriculture/104624>
Onion farmers in Kiambu have been advised to seek agriculturists' attention over the outbreak of stemphylium leaf blight onion disease.
An agriculturist officer noted that the disease is caused by heavy rains and needed serious attention before destroying the crop. He warned that the crops can wither a month after discovery of the disease if not [treated] immediately.
He noted that [in] the whole [of] Gatundu North Sub County, onion farmers might have been affected and urged them to apply treatment as early as they discover the disease to avert loss of yields.
[Byline: Matthew Ndung'u]
--
Communicated by: ProMED-mail <promed@promedmail.org>
[Leaf blight and stem rot of onion is caused by the fungus _Stemphylium vesicarium_. It is a serious disease of the crop that can lead to yield losses and severe damage to seed crops. Symptoms include water soaked lesions on leaves with yellow streaks extending along the leaf blade; leaves may become completely blighted, and coalescing lesions may girdle and kill leaves and seed stems. Bulbs are not normally affected, but yield losses are due to weakening of the plants. Symptoms are similar to and may be confused with purple blotch (caused by _Alternaria porri). Disease development is favoured by warm, humid conditions and extended periods of leaf wetness (as mentioned above). The pathogen can also affect a number of other hosts, including crops like tomato, asparagus, soybean and even trees like pear and mango, but symptoms vary on different hosts.
The fungus survives between crops in plant debris or soil. It is spread with contaminated plant and soil material, water, and by mechanical means. Disease management is difficult and mostly relies on cultural methods, phytosanitation (removal of crop debris and reservoir hosts) and fungicides.
Other species in the genus are associated with blights or rotting diseases in a range of crops, such as leaf spot on sugar beet and apple core rot.
Maps
Kenya:
<http://www.ogiek.org/photo-gallery/kenya-map-big.jpg>
Kenya counties:
<http://softkenya.com/county/wp-content/uploads/sites/107/2015/05/Counties-in-Kenya.jpg>
Kiambu sub-counties:
<http://kenyacountyguide.com/home/wp-content/uploads/2014/09/kiambu-map.jpg>
Pictures
Stemphylium leaf blight on onion:
<https://onvegetables.files.wordpress.com/2012/07/fig1_slg-e1341539192196.gif?w=500&h=247>,
<http://www.apsnet.org/edcenter/K-12/NewsViews/Article%20Images/stemphylium.jpg>,
<http://vikaspedia.in/agriculture/crop-production/integrated-pest-managment/ipm-for-vegetables/ipm-strategies-for-onion/leafblightimg.jpg>
and via
<http://www.invasive.org/browse/subimages.cfm?sub=17885> (photo
gallery)
_S. vesicarium_ conidia (microscopy):
<http://media.padil.gov.au/species/143077/51297-large.jpg>
Links
Information on stemphylium blight:
<http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=42014>,
<http://aggie-horticulture.tamu.edu/extension/newsletters/vpmnews/may01/art5may.html>,
<http://www.apsnet.org/publications/phytopathology/backissues/Documents/1989Articles/Phyto79n03_301.PDF>
and via
<http://nhb.gov.in/bulletin_files/vegetable/onion/oni002.pdf>,
<http://vikaspedia.in/agriculture/crop-production/integrated-pest-managment/ipm-for-vegetables/ipm-strategies-for-onion/diseases-and-symptoms>
and
<http://www.actahort.org/members/showpdf?booknrarnr=358_43>
Description of _S. vesicarium_:
<http://www.padil.gov.au/maf-border/pest/main/143077/51298>
_S. vesicarium_ taxonomy:
<http://www.indexfungorum.org/names/NamesRecord.asp?RecordID=339660>
- Mod.DHA
A HealthMap/ProMED-mail map can be accessed at:
<http://healthmap.org/promed/p/174>.]
[See Also:
2014
----
Stemphylium leaf spot, sugar beet - UK: 1st rep (England)
http://promedmail.org/post/20141015.2864444
2009
----
Fungal blight, onion - India: (MH)
http://promedmail.org/post/20090103.0024
2005
----
Apple core rot - India (Himachal Pradesh) http://promedmail.org/post/20050808.2313]
Topics
Species
