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 12 May 2020
Source: Times of India [edited]
<https://timesofindia.indiatimes.com/city/mysuru/after-lockdown-woes-onion-farmers-hit-by-twister-blight/articleshow/75663463.cms>
Onions on hundreds of acres in Chamarajanagara district have been infected by the twister blight [which] twists the leaves of the crops, causing the onions to decay rapidly.
"This is the 1st time that the disease has damaged crops in such a large scale. It has affected the entire district [where] onions are one of the major commercial crops. [The] horticulture department claim that moisture in the soil is causing the damage, but we have had good yield for years despite heavy rainfall," said [a local official].
[A] farmer leader said, "Farmers, without assistance, cannot identify the pesticides to be sprayed for different diseases. To grow good crops, there should [be] agri-clinics with technical assistants, who can guide farmers. The current scenario calls for a survey of the onion crop loss."
[Byline: Lakshmikantha BK]
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Communicated by: ProMED-mail <promed@promedmail.org>
[A number of fungi have been found to be associated with the anthracnose-twister disease complex (ATDC) of onion and other allium crops. Pathogens generally include _Glomerella_, _Colletotrichum_ and _Gibberella_ species. The latter are thought to be primarily responsible for distortion and twisting of leaves. Symptoms may also include water-soaked, pale yellow spots on leaves, which expand lengthwise until covering the entire leaf blade, followed by shrivelling and drooping of affected leaves. Severe crop losses of up to 100 percent have been reported due to ATDC.
The fungi survive on crop debris. Spread occurs mainly with infected plant material and by mechanical means. Disease management may include removal of infected crop debris to reduce inoculum, crop rotation, fungicides (although effectiveness may be limited), biocontrol organisms (for example _Trichoderma_) and cultural measures (reduction of moisture in the crop). Some resistant or tolerant onion cultivars are being developed.
Maps
India (with states):
<http://www.mapsofindia.com/maps/india/india-political-map.htm>
Karnataka districts:
<https://www.mapsofindia.com/maps/karnataka/karnataka.htm>
Pictures
ATDC symptoms on onion:
<https://seminisus.s3.amazonaws.com/app/uploads/2014/11/Screen-Shot-2020-02-13-at-2.35.24-PM.png>
<https://static.vikaspedia.in/media/images_en/agriculture/crop-production/integrated-pest-managment/ipm-for-vegetables/ipm-strategies-for-onion/twisterdiseaseimg.jpg>,
<https://tuyisengemoses.files.wordpress.com/2017/05/img_20170505_102611.jpg>,
<https://plantdoctor.eastwestseed.com/sites/default/files/styles/diagnosis/public/pic%20027.jpg>
and
<https://plantdoctor.eastwestseed.com/sites/default/files/styles/diagnosis/public/EW_%20014.jpg>
Links
Information on onion ATDC:
<https://plantdoctor.eastwestseed.com/diagnostic-key/anthracnose-twister>
(with pictures),
<https://vikaspedia.in/agriculture/crop-production/integrated-pest-managment/ipm-for-vegetables/ipm-strategies-for-onion/diseases-and-symptoms>,
<https://www.seminis.com.au/resources/disease-guides/onions/twister/>,
<https://pnwhandbooks.org/plantdisease/host-disease/onion-allium-cepa-twister>
and via
<https://tuyisengemoses.wordpress.com/2017/05/25/oniononiononiononion-disease/>
ATDC aetiology and risk assessment
<https://doi.org/10.20546/ijcmas.2018.712.413>,
<https://eagronfiles.wordpress.com/2009/05/28/scientists-identify-two-anthracnose-pathogens-attacking-onions/>,
<https://link.springer.com/article/10.1007/s41324-018-0229-4> and <https://www.bar.gov.ph/index.php/news-and-events/925-2009-06-pathogens>
Fungal taxonomy and synonyms via:
<http://www.indexfungorum.org/Names/Names.asp>
- Mod.DHA]
[See Also:
2016
----
Anthracnose & purple blotch, onion - Philippines: (IN)
http://promedmail.org/post/20160729.4378522
2011
----
Purple blotch & anthracnose, onion - India: (MH)
http://promedmail.org/post/20110103.0024
2010
----
Purple blotch & anthracnose, onion - India: (MH)
http://promedmail.org/post/20110103.0024
2009
----
Fungal blight, onion - India: (MH)
http://promedmail.org/post/20090103.0024
and additional items on anthracnose diseases in the archives]
Topics
Species
