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 22 Aug 2019
Source: The Western Producer [abridged, edited] <https://www.producer.com/2019/08/chickpea-disease-confounds-experts/>
A mysterious disease is plaguing chickpea crops in southern Saskatchewan. Blighted and diminished plants are being found, [and the] disease confounds growers and agronomists. [The] unusual outbreak swept across wide swaths of the Canadian chickpea crop in July [2019].
"The issue went across pretty much all of Western Canada and the northern (United States)," said Sherrilyn Phelps, Saskatchewan Pulse Growers. CDC Orion [chickpea cultivar] seemed to be more affected than other varieties, which could mean its resistance to ascochyta may be breaking down. "We saw that happen about 15 years ago when Sanford was the most popular variety, but over about a 3-year period it's tolerance to ascochyta was broken down," she said. "The same thing could be happening right now with the Orion."
Ascochyta was present in some of the fields, but Phelps said the blighting wasn't ascochyta in a lot of cases. "It seems to be related to some sort of stress, and it just made the crop more susceptible to the symptoms," Phelps said. "Overall, no one specific factor seems to be consistent," she said.
Samples have been sent to be evaluated for foliar disease, fungicide resistance, [and] to see what root diseases are present. The extent of damage the disease caused won't be known until the chickpeas are harvested. Chickpea is the main pulse in southern Saskatchewan, so this outbreak has many growers on edge. "Hopefully we'll have some answers prior to next year (2020)."
[Byline: Robin Booker]
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Communicated by: ProMED-mail <promed@promedmail.org>
[Ascochyta blight (AB) of chickpea is caused by the fungus _Mycosphaerella rabiei_ (previously _Ascochyta rabiei_) and is considered the most important disease of chickpeas worldwide. The pathogen attacks all aerial portions of the plant and is specific to chickpeas. Disease development is favoured by cool, wet conditions.
Symptoms may include spots and lesions on leaves, stems and pods, which may lead to partial wilting, or the whole shoot may break off and the plant will die. Infected seeds are shriveled, spotted and discoloured.
The pathogen can survive on infected plant material for at least 2 years under dry conditions, but viability is lost rapidly in high humidity. It is seed borne at a high rate of 50% to 80%. Seed transmission is the primary mode of spread both locally and worldwide.
Disease management includes cultural methods, seed treatment, preventative fungicide applications and use of varieties with improved resistance.
Fungal strains with increased virulence that have broken host resistance in currently used cultivars have emerged elsewhere, for example, in Australia (ProMED-mail post
http://promedmail.org/post/20150925.3669437) where they are considered a threat to the national chickpea industry.
AB of lentils is caused by the fungus _Didymella lentis_ (previously _Ascochyta lentis_). The 2 pathogens are now classified into different genera, but the same common name derived from their previous classification is still used for both diseases.
Maps
Canada (with provinces):
<http://mapsof.net/uploads/static-maps/Canada_Provinces_and_territories_map.png>
Pictures
AB symptoms on chickpea:
<http://www4.agr.gc.ca/resources/prod/img/pmc/img/1247678986193_img1.gif>,
<https://www.plantmanagementnetwork.org/pub/php/research/2009/chickpea/image/chickpea1sm.jpg>,
<http://agriculture.vic.gov.au/__data/assets/image/0007/274291/3.jpg>
and
<http://www.pulseaus.com.au/storage/app/uploads/public/568/07f/6cd/thumb_244_360x240_0_0_crop.jpg>
AB affected chickpea field:
<http://agriculture.vic.gov.au/__data/assets/image/0003/274287/1.jpg>
Chickpea varieties, comparison susceptible vs. resistant to AB:
<http://www.forestryimages.org/browse/detail.cfm?imgnum=5475102>
Chickpea AB, photo gallery:
<http://www.forestryimages.org/browse/subthumb.cfm?sub=14270>
Links
Information on chickpea AB:
<http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/plant-diseases/grains-pulses-and-cereals/ascochyta-blight-of-chickpea>,
<http://www.pulseaus.com.au/growing-pulses/bmp/chickpea/ascochyta-blight>,
<https://www.researchgate.net/publication/248909930_Ascochyta_blight_of_chickpea_Infection_and_host_resistance_mechanisms>,
<https://www.plantmanagementnetwork.org/pub/php/research/2009/chickpea/>,
<http://www.northernpulse.com/uploads%5Cresources%5C722%5Chandout-chickpeaascochyta-nov13-2011.pdf>,
<http://oar.icrisat.org/184/1/24_2010_IB_no_82_Host_Plant.pdf> and <http://www.publish.csiro.au/paper/AR04143.htm>
_M. rabiei_ disease cycle:
<http://tinyurl.com/jfsqzna>
_M. rabiei_ taxonomy and synonyms:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=466036>
and
<http://www.speciesfungorum.org/Names/SynSpecies.asp?RecordID=466036>
CDC Orion chickpea cultivar:
<http://washingtoncrop.com/crops/cdc-orion/>
- Mod.DHA]
[See Also:
2016
----
Ascochyta blight, chickpea - Australia: (SA) new strains
http://promedmail.org/post/20160826.4442540
2015
----
Ascochyta blight, chickpea - Australia: (VI) new strain
http://promedmail.org/post/20150925.3669437
2014
----
Ascochyta blight, chickpea - Australia: (SA, VI)
http://promedmail.org/post/20140604.2518241
2010
----
Ascochyta blight, lentil - Australia: (SA)
http://promedmail.org/post/20100927.3496
Ascochyta & undiagnosed disease, chickpea - Australia
http://promedmail.org/post/20100903.3145
Ascochyta blight, chickpea - Australia: (NS)
http://promedmail.org/post/20100802.2589
2008
----
Ascochyta blight, chickpea - Australia (02): (QLD)
http://promedmail.org/post/20081008.3186
Ascochyta blight, chickpea - Australia: (QLD)
http://promedmail.org/post/20080828.2698
2007
----
Fungal blights, wheat, corn & chickpea - USA (NB, MT)
http://promedmail.org/post/20070621.2000
2003
----
Ascochyta blight, chickpea - Chile
http://promedmail.org/post/20030604.1368
2002
----
Ascochyta blight, chickpea - USA (Nebraska)
http://promedmail.org/post/20020710.4714
1999
----
Chick pea disease (ascochyta blight) - Australia http://promedmail.org/post/19990731.1298]
Topics
Species
