March 21, 2006
From: ProMED-mail<promed@promedmail.org>
Source: USDA Cereal Rust Bulletin 2006: Number 1 [edited]
<http://www.ars.usda.gov/Main/docs.htm?docid=9757>
Cereal Rust Bulletin, Report No. 1
- Wheat leaf rust is present at low levels in
fields and plots in the southern U.S.
- Wheat stripe rust is present at low levels in fields and plots
in the southern U.S.
- Traces of oat stem rust were found in Louisiana plots.
- Oat crown rust is present at low levels in the southern U.S.
- Barley stripe rust was found in Arizona plots.
- Wheat stem rust has not yet [March 2006] been reported in the
U.S. in 2006.
By early March [2006], cultivars growing in plots in southeast
Louisiana had up to 70 percent leaf rust severity. The high leaf
rust infections were observed on cultivars that were not
vernalized properly and are not commonly grown in Louisiana.
Stripe rust development in Texas is at a much lower level than
last year [2005] on the same date.
--
ProMED-mail
<promed@promedmail.org>
[There are 3 main rust diseases of the cereal crop plant wheat
(bread wheat, _Triticum aestivum_ and durum wheat, _Triticum
turgidum_). These are wheat stem rust (_Puccinia graminis f.sp.
tritici_), wheat leaf rust (_P.
triticina_ aka _P. recondita f. sp. tritici_) and wheat stripe
rust (_P. striiformis f. sp. tritici_), all caused by species of
the fungus Puccinia.
Severe losses that can occur due to wheat stem rust have been
abated in the USA since the 1960's by effective resistance
breeding, though the knowledge of resistance breaking strains of
the pathogen, such as Ug99 in Uganda, is a concern [note "see
also"]. Severe losses are still a possibility with leaf rust. As
recently as 1993, leaf rust destroyed over 40 million bushels of
wheat in Kansas and Nebraska. In 1985, Texas and Oklahoma lost
95 million bushels of wheat to leaf rust. The USDA Cereal
Disease Laboratory St. Paul, MN publishes regular reports on
cereal rusts in the USA during the crop season. 10 were
published between March and September 2005. Each report gives
detailed state-by-state information, including a summary map,
all in pdf file format [see link to main article]. Wheat is not
doing well in early 2006 in southern states because of drought,
e.g. in Texas and Oklahoma. This condition is also not conducive
for leaf rust, which partly explains the low levels of incidence
reported so far [March] in 2006.
Map:
Puccinia spore pathway
<http://www.ars.usda.gov/Main/docs.htm?docid=11301>
Wheat in USA
<http://www.nass.usda.gov/research/atlas02/Crops/Field%20Crops%20Harvested/Wheat/All%20Wheat%20for%20Grain,%20Harvested%20Acres-chor.gif>
Pictures:
Wheat leaf rust
<http://www.cdl.umn.edu/nomenclature/inf_set.jpg>
Wheat stem rust
<http://www.gov.mb.ca/agriculture/crops/diseases/images/fac15s01.jpg>
Wheat stripe rust
<http://www.utextension.utk.edu/fieldCrops/wheat/Wheat_photos/Wheat_StripeRust.jpg>
Links:
<http://www.ars.usda.gov/Main/docs.htm?docid=9854>
- Mod.JAD]
[see also in the
archive:
2005
----
Wheat stem rust, Ug99, new strain - East Africa 20050928.2849
Wheat stem rust, new strain - Uganda 20050912.2698]
