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Date: August, 2007
[1] Stripe rust, wheat - Australia (South Australia)
[2] Chocolate spot, faba bean - Australia (South Australia)

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[1] Stripe rust, wheat - Australia (South Australia)

Date: Thu 16 Aug 2007
Source: Australian Broadcasting Corporation, Rural [edited] <http://www.abc.net.au/rural/news/content/2007/s2006869.htm>

Stripe rust has been found in a crop in the lower north of South Australia. The fungal disease affects wheat crops and can halve crop yield.

Agronomist Bill Long says the affected crop is well developed and farmers should be looking out for other outbreaks. "Experience with stripe rust in the past is that it can spread quite quickly, given the right conditions, and I guess we've had a slightly warmer July and early August [2007] than we've thought," he said. "With a little bit of moisture I would expect that this disease could move reasonably rapidly throughout the cropping districts."

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

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[2] Chocolate spot, faba bean - Australia (South Australia)

Date: Wed 15 Aug 2007
Source: Australian Broadcasting Corporation, Rural [edited] <http://www.abc.net.au/rural/news/content/2007/s2005861.htm>

Rainfall in early September [2007] may spell disaster for some pulse crops in South Australia.

_Botrytis fabae_, otherwise known as chocolate spot, has been identified in some faba bean crops in South Australia. The disease is a mouldy fungus, which spreads in humid conditions and if there is a wet spring it has the potential to wipe out large areas of pulse crops.

The South Australia Research and Development Institute's Jenny Davidson says the disease was not expected this early. "Chocolate spot likes to have warmish wet conditions. While these faba bean crops were relatively humid, because of the cold weather we've been seeing we hadn't anticipated that chocolate spot would be underway so we're a little bit surprised."

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

[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 percent. 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.

Chocolate spot caused by the fungus _Botrytis fabae_ is an important disease of pulses (annual leguminous crops) including faba bean (_Vicia faba_; also called broad bean, horse bean, Windsor bean, field bean, winter bean). It is 1st seen as brown spots appearing on lower leaves. This is its 'non-aggressive' phase, which is thought to have little effect on crop yield. If warm, humid conditions persist for several days, the disease will spread quickly and be termed 'aggressive'. It is one of the most destructive diseases in the region of the Nile Delta and other African regions, such as Ethiopia.

The disease progresses with blighting of leaves, defoliation and loss of flowers and pods. Stems can weaken with a strong tendency to collapse. Flowers and pods may also develop lesions, although affected seeds are still edible. The fungus may produce a plant toxin thought to be responsible for the damage to the host tissue. A strong relationship exists between disease infection in the podding region and seed yield. Disease management includes burning of plant residue at the end of cropping, wide spacing of plants, limiting the amounts of nitrogenous fertilizers, crop rotation, use of clean seed, control of volunteer plants, and fungicides. Host cultivars with varying levels of tolerance are being developed.

The related, more virulent species _B. cinerea_ affects a similar range of crops intermittently, and is usually confined to the flowering season. Other species in the genus affect a range of crops, and many have a worldwide distribution.

Cultivated faba bean is used as food (important in many developing countries), animal feed, and sometimes grown for green manure and crop rotation. Faba bean straw is used for brick making and as fuel and considered a premium cash crop in Egypt, Ethiopia, and Sudan.

Maps
Australia:
<http://www.ga.gov.au/image_cache/GA4073.jpg>
South Australia:
<http://www.ozhorizons.com.au/sa/map.htm>

Pictures
Stripe rust, wheat leaf symptoms:
<http://www.ars.usda.gov/Main/docs.htm?docid=9918&pf=1&cg_id=0>
Chocolate spot on faba bean leaves:
<http://www.inra.fr/internet/Produits/HYP3/images/6030610.jpg>
Symptoms on whole faba bean plant:
<http://www.inra.fr/internet/Produits/HYP3/images/6030616.jpg>
Chocolate spot on faba bean, various plant parts:
<http://www.winter-beans.co.uk/Disease/chocimg.asp>

Links
Information on wheat stripe rust:
<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>
_P. striiformis_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=427989>
Information on chocolate spot:
<http://www.winter-beans.co.uk/Disease/choc.asp>,
<http://www.inra.fr/internet/Produits/HYP3/pathogene/6botfab.htm>,  and <http://www.dgsgardening.btinternet.co.uk/chocolate.htm>
Information on faba bean and its diseases in Australia:
<http://www.agric.nsw.gov.au/reader?MIvalObj=18818&doctype=document&MItypeObj=application/pdf&ext=.pdf>
Diseases of faba bean:
<http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm7810>
_B. fabae_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=264556>
_B. cinerea_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=217312>
Phylogeny of genus _Botrytis_:
<http://mbe.oxfordjournals.org/cgi/content/full/msi020?ijkey=42Y3fBaCgcqCM&keytype=ref>. 
- Mod.DHA]

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

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