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: 7 October 2008
Source: Queensland Country Life [edited]
<http://qcl.farmonline.com.au/news/state/grains-and-cropping/general/ascochyta-outbreak-in-highlands-chickpeas/1327387.aspx>

Ascochyta outbreak in highlands chickpeas

There is another confirmed outbreak of ascochyta blight (AB) in a Central Queensland chickpea crop located south of Emerald on the Central Highlands. Department of Primary Industries and Fisheries [DPI&F] senior development extension officer, Anne Shepherd, said that while the confirmed infection of this crop is disappointing, growers and agricultural consultants were well informed and well positioned to provide effective ascochyta blight management advice.

Pulse Australia northern region development officer Gordon Cumming said Central Queensland could no longer claim to be AB-free, but remained a low risk location. The 1st reported Central region outbreak was reported in the Dawson-Callide on 22 Aug [2008] [see ProMED-mail post no. 20080828.2698], which currently involves 7 chickpea crops on 5 properties within the same district.

Mr Cumming said growers need to adopt suitable AB monitoring and control strategies in the coming seasons to ensure the region remains at low risk. "This means ensuring that all planting seed is sourced from Central Queensland and that all seed -- especially grower-retained -- is treated with a registered fungicide seed dressing," Mr Cumming said.

Ms Shepherd said the industry's recommended response plan prepared in
2006 by DPI&F and Pulse Australia outlines the AB disease management strategy and has been rigorously adopted by the involved growers.
"Growers and industry consultants are to be congratulated for their quick response," Ms Shepherd said. She urged growers to remain vigilant and inspect all crops that are still green for AB symptoms.

The bulk of this year's estimated 50 000-hectare (123 553-acre) chickpea winter crop is starting to hay off, which will make identification of the brown lesions on AB infected plants difficult.
"Any suspect or confirmed AB infected crops should be harvested last and none of the seed should be graded in Central Queensland or retained for future planting," Ms Shepherd said. "Particular attention should be given to machinery hygiene during the harvest, and equipment must be thoroughly cleaned before entering a new property."

--
Communicated by:
ProMED-mail Rapporteur Susan Baekeland

[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 percent. 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%20020908/$file/020908-regional-boundaries.pdf>
Pictures
AB symptoms on chickpea:
<http://www.icarda.cgiar.org/ICARDA_photogallery/Constraints/Carv12-18b.jpg>
(leaves),
<http://paridss.usask.ca/specialcrop/pulse_diseases/images/CAscoPod1LBThumb.jpg>
(pod),
<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>
(with pictures)
_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]