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: 26 August 2008
Source: Queensland Country Life [edited]
<http://qcl.farmonline.com.au/news/state/grains-and-cropping/general/ascochyta-outbreak-in-central-qld/1254166.aspx>

Ascochyta outbreak in Central Queensland

Central Queensland's status as the only ascochyta blight-free chickpea cropping area in Australia is under threat following a confirmed outbreak of this fungal disease in a few Dawson-Callide crops. Department of Primary Industries and Fisheries [DPI&F] principal plant pathologist, Dr Mal Ryley, inspected the suspect crops on 22 Aug [2008] with DPI&F pulse research scientist, Col Douglas, and Pulse Australia northern region development officer, Gordon Cumming.

Ascochyta blight (AB) is responsible for serious chickpea production losses throughout southern cropping areas and this 1st confirmed outbreak [in this region] has triggered the industry action response plan only launched in April [2007]. Dr Ryley urged all Central Queensland growers to check their
2008 season crop for any signs of the disease.

Dead leaves and broken stems are usually the 1st indication of infection with the stems often breaking near the lesion. "This year's [2008] Central Queensland chickpea crop covers an estimated 50 000 hectares [123 553 acres] so it is imperative that all regional growers are well informed and well positioned to contain and defuse this confirmed AB outbreak," Dr Ryley said.

The current chickpea varieties grown in Central Queensland are very susceptible to ascochyta blight. Dr Ryley said the recommended AB disease management strategy involves 5 vital steps: farm hygiene; timely fungicide spray applications; crop management; ensuring that no chickpeas are grown in the paddock for 3 years; and making sure that planting seed from this crop is not retained.

Figures:
[1] Ascochyta blight fungal disease stem lesion -- a symptom of the disease found for the first time in Central Queensland's cropping area.
<http://qcl.farmonline.com.au/multimedia/images/full/346827.jpg>
[2] Leaf lesions -- a telltale symptom of ascochyta blight.
<http://qcl.farmonline.com.au/multimedia/images/full/346826.jpg>

--
communicated by:
ProMED-mail
<promed@promedmail.org>

[Ascochyta blight (AB) of chickpea is caused by the fungus _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 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 50-80 per cent. Seed transmission is the primary mode of spread both locally and worldwide. Disease management includes cultural methods, seed treatment, prophylactic fungicide applications, and use of varieties with improved resistance.

_A. rabiei_ has previously caused serious losses to chickpea crops in southern Australia. _A. lentis_ causes a similar blight in lentils and _A. pinodes_ in peas.

Maps
Australia:
<http://www.ga.gov.au/image_cache/GA4073.jpg>  and <http://healthmap.org/promed?v=-25.7,134.5,4>
Queensland:
<http://www.ozhorizons.com.au/qld/map.gif>
Queensland districts (local government areas):
<http://www.mainroads.qld.gov.au/web/AttachStore.nsf/allobjects/New%20administrative%20boundaries%20map/$file/080404-regional-boundaries.pdf> 

Pictures
AB symptoms on chickpea:
<http://www.icarda.cgiar.org/ICARDA_photogallery/Constraints/Carv12-18b.jpg>
(leaves),
<http://www.dpi.qld.gov.au/images/News/AscochytaLesions-OnChickpeaStem-250.jpg> 

(stem lesions)
Chickpea field affected by AB:
<http://www.dpi.qld.gov.au/images/Biosecurity_GeneralPlantHealthPestsDiseaseAndWeeds/Chickpeas-AscochytaInChickpeas-250.jpg> 

_A. rabiei_ emerging from infected seeds:
<http://www.pdsl.ca/images/Chickpea%20-%20Asc,%20Scler.JPG>
Links
Information on chickpea AB:
<http://www.dpi.qld.gov.au/cps/rde/xchg/dpi/hs.xsl/26_4501_ENA_HTML.htm>,
<http://highplainsipm.org/HpIPMSearch/Docs/AscochytaBlight-Chickpea.htm>,  and <http://paridss.usask.ca/specialcrop/pulse_diseases/chickpea/ascochyta.html>
_A. rabiei_ disease cycle:
<http://www.agriculture.gov.sk.ca/adx/aspx/adxGetMedia.aspx?DocID=1016,1009,340,185,81,1,Documents&MediaID=732&Filename=disease_cycle_final.jpg> 

_A. rabiei_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=275994>.  - Mod.DHA]