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Date: 20 Sep 2007
Source: FarmOnline [edited]
<http://www.farmonline.com.au/news_daily.asp?ag_id=45541>

South Australian wheat crops are under pressure from the new strain of stripe rust -- with virulence for the Yr17 resistance gene -- discovered in Victoria and New South Wales last year [2006].

SARDI [South Australian Research and Development Institute] pathologist Dr Hugh Wallwork says the new strain of stripe rust could be more damaging than all previous strains, and reminds growers that allowing rust to develop on susceptible wheat varieties increases the rate at which new strains evolve. Stripe rust has recently been identified at a number of sites in SA.

--
communicated by:
J Allan Dodds
former ProMED-mail plant disease moderator <dodds@ucr.edu>

[Wheat stripe rust (also called yellow rust) is caused by the fungus _Puccinia striiformis_ var. _striiformis_ and occurs worldwide mostly in cooler climates. It causes yellow leaf stripes, stunting of plants, and reduced grain number and size on developing heads. Yield losses may vary from 40 up to 100 per cent. It affects wheat, some barley varieties, triticale, and a number of grass species. Spores are wind dispersed in several cycles during the cropping season. The fungus needs living plants to survive between seasons, it cannot survive on seed, stubble, or in soil.
Volunteer plants may generate a "green bridge" providing inoculum to infect new crops. Disease management strategies include the use of resistant varieties, fungicide applications and control of volunteer wheat plants.

Since the fungus interferes with seed development, infection early in the crop cycle is more damaging than infection after seed fill has concluded.
Early discovery of infection at any stage of the crop cycle is important so action can be taken to limit the spread of the pathogen as well as build-up of inoculum.

The Australian Cereal Rust Control Program monitors the occurrence of cereal rust pathotypes each year and in 2003, for example, 6 pathotypes of stripe rust were identified throughout Australia. The new strain reported here has apparently overcome one of the major stripe rust resistance genes used in wheat breeding and may pose a serious problem to farmers in eastern Australia.

Maps
Australia:
<http://www.ga.gov.au/image_cache/GA4073.jpg>
South Australia:
<http://www.ozhorizons.com.au/sa/map.htm>
Pictures
Stripe rust leaf symptoms on wheat:
<http://www.ars.usda.gov/Main/docs.htm?docid=9918&pf=1&cg_id=0>  and
<http://utextension.tennessee.edu/fieldCrops/wheat/Wheat_photos/Wheat_StripeRust.jpg> 

Symptom comparison on resistant and susceptible wheat cultivars:
<http://www.oznet.ksu.edu/path-ext/factSheets/wheat/Wheatimages/wheats1.jpg>
Links
Grains Research and Development Corporation media release at:
<http://www.grdc.com.au/director/events/mediareleases/?item_id=2543CB96D33AC3EA95168CD63636B2C3> 

Information on wheat stripe rust:
<http://www.hgca.com/hgca/wde/diseases/Yellow%20rust/Yrhost.html>,
<http://www.ars.usda.gov/Main/docs.htm?docid=9918&pf=1&cg_id=0>  and
<http://www.oznet.k-state.edu/path-ext/factSheets/Wheat/Wheat%20Stripe%20Rust.asp> 

Stripe rust management:
<http://www.grdc.com.au/uploads/documents/striperustmgt.pdf>
_P. striiformis_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=427989>
General information on wheat diseases and pathogens:
<http://www.apsnet.org/online/common/names/wheat.asp>
Explanation of strains, pathotypes, and races of rusts:
<http://www.grdc.com.au/director/events/groundcover?item_id=publication-issue53&article_id=482B978094DEDBDD18CDA8C0DCD4F6C2>
SARDI:
<http://www.sardi.sa.gov.au>.  - Mod.DHA]


[see also in the archive:
Stripe rust, wheat & wheat streak mosaic - Australia (SA, WA) 20070830.2860
Fungal diseases, wheat & pulses - Australia (SA) 20070821.2729
Stripe rust, wheat - USA, Australia 20070614.1950
2005
---
Stripe rust, wheat - Australia 20051031.3173
2004
---
Wheat stripe rust - Australia (NSW) 20040928.2683
Wheat stripe rust - Australia (NSW): alert 20040810.2215
2003
---
Wheat stripe rust, new strains - Australia (SA) 20030930.2465
Wheat stripe rust - Australia (WA) 20030624.1553
2002
---
Wheat stripe rust - Australia (Western): alert 20020831.5198]

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