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: April 8, 2008
Source: China View [edited]
<http://news.xinhuanet.com/english/2008-04/08/content_7938467.htm>
China gears up to battle wheat, rape diseases
China is enhancing its efforts to battle plant diseases
spreading in the country's wheat and rape plantations.
As of 1 Apr [2008], 9.52 million mu (634 667 hectares) of the
country's wheat has developed stripe rust, a serious disease
caused by a soil-borne fungus, according to Ministry of
Agriculture statistics released on Monday [7 Apr 2008].
Meanwhile, 17.33 million mu of [oilseed] rape have been affected
by a devastating disease called sclerotinia. The situation might
get worse as the April-June period is a season prone for plant
diseases and insect pests with warm weather and frequent
rainfalls expected.
According to a ministry forecast, the current disease reports
would only account for 24 and 39 percent of the total areas of
wheat and rape plantings, respectively, that could develop such
diseases this year. However, the ministry did not say the
proportion of the disease-affected area in the sown area. The
ministry has told local governments to beef up their control of
the spread of such diseases and intensify monitoring. Local
governments were required to quickly report new infections to
higher-level authorities.
[Byline: An Lu, editor]
--
Communicated by:
ProMED-mail
<promed@promedmail.org>
[Wheat stripe rust
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
(wheat/rye hybrids), and a number of grass species. Spores are
wind dispersed in several cycles during the cropping season.
Since the fungus interferes with seed development, infection
early in the crop cycle is more damaging than infection after
seed fill has concluded.
Spores are dispersed by wind and mechanical means. 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. New pathogen strains
with increased virulence have been reported from several wheat
growing areas. Disease management includes the use of resistant
varieties, fungicide applications, and control of volunteer
cereals. Disease monitoring, which according to the above report
is now being undertaken by the Chinese authorities, is important
so timely action can be taken to limit the spread of the
pathogen as well as build-up of inoculum.
Oilseed rape sclerotinia
Sclerotinia of oilseed rape (also called stem rot, white mold),
is caused by the fungus _Sclerotinia sclerotiorum_. This
soil-borne fungus is among the most nonspecific, omnivorous and
successful of plant pathogens and is present worldwide in a wide
range of climates.
Almost 400 host species are known, including many broad leaved
crops.
The pathogen is primarily soil-borne and has a complex disease
cycle.
Normally, spores must first germinate on dead plant material
such as dead leaves or fallen flower petals caught in between
the stems and leaves, before they can invade healthy tissues.
Cool, wet weather favours the disease providing enough moisture
for infection. On oilseed rape, infected leaves collapse around
the stem, then stem lesion showing a typical bleached appearance
develop. Infections high on the stems result in contamination of
the seed with sclerotia (hard survival structures).
The fungus can survive in soil as sclerotia and is also spread
by infected plant material, mechanical means and wind-borne
spores. It is thought that it may also survive in the soil by
colonising the roots of other plant species which then serve as
inoculum sources for crops. Risk of crop infection depends on
the previous disease history of a field as well as weather
conditions. Disease management includes cultural practices (such
as long-term crop rotation with non-hosts) and fungicide
applications. A related species, _S. minor_, also causes similar
blight diseases on a number of crops.
Maps
China:
<http://www.chinapage.com/map/map.html>
and <http://healthmap.org/promed?v=36.5,103.9,4>
Provinces of China:
<http://www.sacu.org/provmap.html>
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>
Sclerotinia of oilseed rape:
<http://www.hgca.com/research/OSRWeb/Images/disease.JPG>
and <http://www.agric.wa.gov.au/ikmp/images/sclerotinia_further.jpg>
(stems), <http://www.hgca.com/research/OSRWeb/Images/Control2.JPG>
(leaves)
Links
Information on wheat stripe rust:
<http://pnw-ag.wsu.edu/smallgrains/Stripe%20Rust.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>
Information on sclerotinia of oilseed rape:
<http://www.agric.wa.gov.au/pls/portal30/docs/FOLDER/IKMP/FCP/CO/PW/BULLETIN4406A.HTM#sclerotinia>
and
<http://www.hgca.com/publications/documents/cropresearch/Topic77.pdf>
Information on _S. sclerotiorum_:
<http://www.extento.hawaii.edu/kbase/Crop/Type/s_scler.htm>
and <http://www.cals.ncsu.edu/course/pp728/Sclerotinia/S_sclerotiorum.html>
_S. sclerotiorum_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=212553>
- Mod.DHA]
[see also in
the
archive:
Sharp eyespot, wheat - China 20080325.1119 Stripe rust, wheat -
Denmark: new strains 20080211.0542 Fungal diseases, potato -
Bangladesh 20080107.0091
2007
----
Stripe rust, wheat - Australia (SA): new strain 20070921.3135
Stripe rust, wheat & wheat streak mosaic - Australia (SA, WA)
20070830.2860 Ergot & stripe rust, cereals - USA (MT)
20070706.2144 Stripe rust, wheat - USA, Australia 20070614.1950
Wheat stripe rust, wheat - China 20070413.1230
2005
----
Stripe rust, wheat - Australia 20051031.3173 Wheat stripe rust -
USA (FL) 20050601.1521
2004
-----
Sclerotinia blight, peanut - USA (TX) 20041001.2702 Wheat stripe
rust - Australia (NSW) 20040928.2683 Wheat stripe rust -
Australia (NSW): alert 20040810.2215 Wheat stripe rust - China
20040429.1191
2003
----
Wheat stripe rust, new strains - Australia (SA) 20030930.2465
Wheat stripe rust - Australia (WA) 20030624.1553 Wheat stripe
rust, first report - USA (Florida) 20030516.1220
2002
----
Wheat stripe rust - Australia (Western): alert 20020831.5198
Sclerotinia spp., sunflower wilt - Spain 20020706.4677
2001
----
Sclerotinia shoot blight, grapevine - Chile 20011103.2724 Wheat
stripe rust - USA (Great Plains) 20010715.1366 Wheat stripe rust
- USA (Central) 20010629.1236
1999
----
Stripe rust, barley - Australia (Victoria & NSW) 19991116.2043]
