A ProMED-mail post
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International Society for Infectious Diseases
http://www.isid.org

Date: Sun 6 Jun 2021
Source: Nairobi Star [abridged, edited]
https://thenairobistar.com/2021/06/06/farmers-in-narok-staring-at-losses-as-head-smut-disease-ravages-crop/


Maize farmers in Narok [County] are staring at losses in crop yields
following the outbreak of head smut disease suspected to be linked
with fake seeds. Most of the farmers claim to have bought 'genuine'
seeds.

According to a large-scale maize farmer, his crop was lush in the
initial stages up to the production stage when he realised that the
cobs had been affected by head smut. "I did 168 acres [68 ha] of
maize; in every 5 maize plants, 3 had head smuts," he said. "I
purchased my seeds through a renowned agent, but from these yields, I
doubt the seed quality."

[Another farmer] who owns a 10-acre [4 ha] maize farm, is also
experiencing the same problem. "Last year [2020] I harvested 22 90kg
bags per acre, but this year [2021] I will be lucky if I get 5 bags
per acre," he said.

--
Communicated by:
ProMED
promed@promedmail.org

[Head smut caused by _Sporisorium reilianum_ (previously
_Sphacelotheca reiliana_) can affect both maize and sorghum; each of 2
existing strains is restricted to one of the hosts. In maize, it
infects the young seedling systemically, then grows through the plant
without inducing symptoms, until it eventually reaches reproductive
tissues (ears and/or tassels) replacing them with galls producing
masses of black spores. Plants may be stunted, distortion is common,
leafy structures may replace the plant's ears or flowering components
(phyllody). Infection of the host occurs mainly during seed
germination. Cool weather, dry seed bed conditions, and nitrogen
deficiency favour the disease.

The fungus survives in the soil and can be seed borne. Spores can be
spread by wind over long distances and mechanical means (such as on
contaminated materials or tools). Disease management may include
cultural techniques (such as long crop rotation), phytosanitary
measures, and the use of disease-free seed. Some resistant crop
varieties are available.

Although the claim above that contaminated seed is the cause of the
outbreak is plausible, the previous cultivation or head smut history
of the affected fields is not clarified. Therefore, presence of the
fungus in the soil from previous maize crops or infections due to wind
borne spores from other areas cannot be excluded.

Maps
Kenya:
https://www.nationsonline.org/maps/kenya_map.jpg and
http://healthmap.org/promed/p/11462
Kenya counties:
https://maps-kenya-ke.com/img/1200/map-of-kenya-counties.jpg

Pictures
Head smut symptoms on maize:
https://www.pioneer.com/CMRoot/pioneer/us/images/agronomy/field_facts/corn/head-smut-corn-ear.jpg,
https://www.plantwise.org/knowledgebank/factsheetadmin/uploads/factsheets/38cb4f49-3505-4005-a772-27cac089e139.jpg,
https://c1.staticflickr.com/9/8242/8509914135_a0b546d32b_b.jpg, and
https://crop-protection-network.s3.amazonaws.com/articles/Head-smut-2014-Adam-Sisson-1.jpg
Head smut on sorghum:
http://www.agroatlas.ru/content/diseases/Sorghum/Sorghum_Sorosporium_reilianum/Sorghum_Sorosporium_reilianum.jpg
and
https://www.researchgate.net/profile/Christopher-Little-2/publication/230888171/figure/fig5/AS:339686859001863@1457999066452/Characteristic-symptoms-of-sorghum-head-smut-caused-by-Sporisorium-reilianum-A-Stunted.png
Photo gallery of symptoms on both hosts:
http://www.forestryimages.org/collections/viewcollection.cfm?id=742

Links
Head smut information:
https://pnwhandbooks.org/plantdisease/host-disease/corn-zea-mays-head-smut
https://www.cabi.org/isc/datasheet/50937,
https://cropprotectionnetwork.org/resources/articles/diseases/head-smut-of-corn,
https://www.dekalbasgrowdeltapine.com/en-us/agronomy/common-smut-and-head-smut-in-corn.html,
https://agrilifecdn.tamu.edu/amarillo/files/2010/11/HeadSmutCorn.pdf,
and
http://www.agroatlas.ru/en/content/diseases/Sorghum/Sorghum_Sorosporium_reilianum/
Head smut disease cycle:
https://alchetron.com/cdn/sphacelotheca-reiliana-e4cded6a-7f85-4141-b852-92ac172a50f-resize-750.jpeg
_S. reilianum_ taxonomy and synonyms:
http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=323849
and
http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=323849
- Mod.DHA]

[See Also:
2019
----
Head smut, maize - Kenya: (NK)
http://promedmail.org/post/20190913.6671716
2016
----
Head smut, maize - Kenya: (Rift Valley)
http://promedmail.org/post/20160819.4426587
2012
----
Smut diseases, sorghum - Uganda: update
http://promedmail.org/post/20120208.1036622
2011
----
Smut diseases, sorghum - Uganda: (NP)
http://promedmail.org/post/20110729.2276
2008
----
Undiagnosed smut, maize - France (02): (Normandy), U. maydis
http://promedmail.org/post/20081030.3417
Undiagnosed smut, maize - France (Normandy)
http://promedmail.org/post/20080922.2980
Fungal alerts - Middle East http://promedmail.org/post/20080909.2817
2007
----
Smut, sorghum - Uganda: (Karamoja)
http://promedmail.org/post/20071216.4051
2000
----
Smut disease, sorghum - Sudan
http://promedmail.org/post/20000121.0099]

Website: http://www.isid.org

Published: June 9, 2021