A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases <http://www.isid.org>

[1] Snow mold - Canada (Ontario)
[2] Leaf rust - USA (Kansas)

******
[1] Snow mold - Canada (Ontario)
Date: Wed 16 Apr 2008
Source: The Mitchell Advocate [edited]
<http://cgi.bowesonline.com/pedro.php?id=56&x=story&xid=393021>

Peter Johnson, a Ministry of Agriculture crop specialist, says farmers are counting on warm temperatures and dry weather before the first seeds are planted, which could be as early as this week or as late as the beginning of June [2008].

"There's no question that we have some snow mould in some early planted wheat and that's a disease that, the longer it's under snow, the worse the disease gets, but in the fields that I've looked at, it looks like most of the plants are still alive," he says.

It's too early to tell if disease or insects will be a problem. White grubs are already making their presence known in larger fields and Johnson says the pests can be quite damaging. Additionally, snow mould is at higher levels this year [2008] than in the past decade due to a continuous snow cover over the winter. "We're not out of the woods by any means," he says.

[Byline: Dan Schwab]

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


[2] Leaf rust - USA (Kansas)
Date: Thu 17 Apr 2008
Source: KTKA 49 News, K-State Ag Today report [edited] <http://www.ktka.com/news/2008/apr/17/kstate_ag_today_producers_should_watch_out_leaf_ru/>

Leaf rust has made its 1st appearance in Kansas this year [2008]. The wheat disease was recently detected in Riley and Barber counties.
K-State Research and Extension plant pathologist Erick DeWolf says recent rains could trigger more outbreaks. Producers that have planted Jagger, Jagalene, or Overley, the 3 top wheat varieties in Kansas, should be especially vigilant.

DeWolf says if producers think they might want to apply a fungicide, they should start crunching the numbers now. "Those most effective fungicides are applied between flag leaf emergence up to flowering, when most of the fungicides we have labels for here in Kansas, would cut out," he said.

[Byline: Jeff Wichman]

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

[Snow molds of wheat include several fungal species. Pink snow mold is caused by _Monographella nivalis_ var. _nivalis_. It attacks plants during wet, cool weather, but is not dependent on snow and can also cause seedling and head blights of cereals. Pink snow mold produces masses of microscopic spores on pink growth. Speckled snow mold is caused by several _Typhula_ species, some of which are restricted to areas with prolonged deep snow cover. Speckled snow mold is grey-white and affected plants tend to bleach and shatter easily. The speckling is due to dark sclerotia (fungal bodies) and may or may not be present.

The snow molds survive in dead leaves of affected plants, or as sclerotia in soil, and generally affect a number of cereal and grass hosts. The pathogens are most aggressive at low temperatures.
Symptoms are most apparent in early spring when the snow first melts.
Plant vigour may be markedly reduced, and in severe cases, the crowns are killed. Surviving plants recover slowly and are sensitive to additional stresses. Disease management includes cultural practices, fungicide applications, and the use of host cultivars suitable to the region, which also have increased levels of resistance or tolerance to the snow molds.

Leaf rust, also called brown rust, on wheat is caused by the fungus _Puccinia recondita_. It reduces the photosynthetic potential of the plant and can cause serious yield losses. Symptoms include brick-red pustules on leaves, stems, and later on heads. As the crop ripens, black spores are produced. The fungus overwinters on volunteer wheat, barley, and certain wild grasses and is spread by wind, mechanical means, and with contaminated plant material. Disease management relies mainly on timely fungicide applications and choice of crop cultivars.

Maps
Canada:
<http://www.lib.utexas.edu/maps/americas/canada_pol_1986.gif>  and
<http://healthmap.org/promed?v=55.4,-101.9,4>
Ontario:
<http://atlas.nrcan.gc.ca/site/english/maps/reference/provincesterritories/ontario/referencemap_image_view>
USA:
<http://www.mapsofworld.com/usa/usa-road-map-enlarge-view.html> and <http://healthmap.org/promed?v=40,-97.6,4>
US states:
<http://www.census.gov/geo/www/us_regdiv.pdf>

Pictures
_Typhula_ snow mold in wheat field:
<http://plant-disease.ippc.orst.edu/plant_images/WheatTyphulaSnowMoldField.jpg>
Snow mold on winter wheat plants:
<http://www.omafra.gov.on.ca/french/crops/facts/90-008f6.jpg>
Leaf rust on wheat:
<http://www.hgca.com/hgca/wde/IMAGES/brown%20rust1.JPG>

Links
Information on snow molds:
<http://www.omafra.gov.on.ca/english/crops/facts/83-046.htm#SNOWM>,
<http://pnw-ag.wsu.edu/smallgrains/Snow%20Mold.html>  and
<http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=1148>
_M. nivalis_ var. _nivalis_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=445552>
Genus _Typhula_ taxonomy:
<http://www.indexfungorum.org/names/genusrecord.asp?RecordID=18704>
Information on wheat leaf rust:
<http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=1138>  and <http://www.hgca.com/hgca/wde/diseases/Brown%20rust/Brhost.html>
_P. recondita_ taxonomy and synonyms:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=145187>.  - Mod.DHA]

[see also in the archive:
Fungal pathogens, wheat - UK (England) 20080319.1055
2007
----
Seedling blight, cereals - UK 20071130.3860 Fungal head blights, wheat - UK 20070816.2674 Fungal pathogens, wheat - United Kingdom: new races 20070523.1652 Rust diseases, bean & wheat - UK: alert 20070512.1515
2006
----
Leaf rust, wheat - Russia (Irkutsk) 20060815.2287
2005
----
Leaf rust, wheat, resistance change - India 20051201.3462 Leaf rust, Septoria spp., wheat - Kazakhstan: corr. 20050825.2509 Leaf rust, Septoria spp., wheat - Kazakhstan 20050823.2488]