.

[1] Ergot, cereal crops
[2] Stripe rust, wheat

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[1] Ergot, cereal crops
Date: Sun 24 Jun 2007
Source: Billings Gazette, Montana State University (MSU) News Service report [edited] <http://www.billingsgazette.net/articles/2007/06/24/news/business/49-fungus.txt>

Montana's cool, wet spring conditions have led to a fungus in cereal crops and grasses that can lead to livestock poisonings, says a Montana State University (MSU) plant pathologist. The fungus is ergot and can poison any livestock, but reports are a bit more frequent when horses or young calves are involved, said MSU's Barry Jacobsen. As little as 0.1 percent ergot in rations can have adverse effects on livestock health and performance.

While MSU has had some reports of infections already, most ergot infections won't be reported for a few more weeks when grasses and cereal grains have headed. "With the conditions we've got, we're going to find it everywhere that it has been wet, and there are only a few places in Montana that have not been wet," Jacobsen said.

While ergot is most common in rye and triticale, it also occurs on wheat and occasionally on barley. It is relatively uncommon in oats, Jacobsen said. Grasses commonly infected include quackgrass, brome grass, red top, feather grass, foxtail, rye grass, orchard grass, crested wheat grass, and timothy. In many cases, ergot produced in
native grasses is the major source of infection for wheat and other cereal crops. Jacobsen said pastures should be checked for ergot infections. If ergot is widespread, the grass heads should be cut and left to dry several weeks before grazing.

The ergot fungus, _Claviceps purpurea_, forms hard purple to black masses that replace individual grains or seeds. These "sclerotia" vary from 1 inch [2.5 cm] long on rye, to less than a quarter-inch on some grasses. In most cases, the sclerotia will be similar or slightly larger than healthy seeds. Soon after infection, a yellowish-white or orange sticky fluid exudes from infected flowers. This is the "honey-dew" stage of the disease. The sticky fluid contains spores of the ergot fungus, which are spread by insects or rain splash to other grass flowers. Infections can take place as long as pollination is occurring. Warm to hot dry weather is unfavorable for infection.

The only treatment for ergot poisoning of animals is to remove the contaminated feeds or remove animals from contaminated pasture. If advanced symptoms are present, a veterinarian should be consulted about supplemental therapy.

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

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[2] Stripe rust, wheat
Date: Sun 24 Jun 2007
Source: Billings Gazette, Montana State University (MSU) News Service report [edited]
<http://www.billingsgazette.net/articles/2007/06/24/news/business/53-rust.txt>

Stripe rust has been confirmed in Gallatin County on susceptible hard white winter wheat varieties. "Conditions have been extremely favorable for stripe rust development, and if it remains cool and wet, we may see this disease blow up very quickly," said Mary Burrows, Montana State University (MSU) Extension plant pathologist.

Germination of the spores is best between 41 and 59 deg F [5 - 15 deg C]. Fungicide application is appropriate through flowering, but once the crop is in the grain-filling stage, fungicides are unlikely to be economically reasonable, Burrows said.

Wheat growers who have planted a variety known to be susceptible to stripe rust need to scout their fields and look for the yellow pustules that occur in stripes, she said. To some extent, the symptoms vary with wheat variety. Symptoms generally are more severe in the bottom of the plant canopy where there is more moisture.

The fungus can affect both winter and spring wheat. A range of wheat varieties is available with different degrees of resistance to stripe rust. A resistant to moderately resistant variety can develop lesions but generally does not have to be sprayed. Moderately susceptible varieties may experience yield losses under severe disease.

If symptoms are seen, and the stand is a susceptible variety with yield potential high enough to justify the cost, fungicide should be sprayed at the 1st appearance of symptoms, Burrows advised. Most registered products have a 45-day waiting period between application and harvest, so grain growers need to consider the interval to crop
maturity.

Stripe rust symptoms can be confused with leaf rust, which also is very prevalent in the Great Plains this summer [2007], though no reports have been received of it in Montana.

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

[The parasitic ergot fungus _Claviceps purpurea_ inhabits northern temperate regions, but it can be found also in subtropical regions. It has a wide host range of grasses (_Graminaea_) with rye being the most frequently affected crop. The species has variable morphology and can be separated into 3 discrete groups based on host species and toxins produced. Sclerotia ("ergots") left behind in the field serve as sources of infection of the next season's crop. Infection reduces grain yield and the fungus produces mycotoxins contaminating the harvested crop.

A number of important medical discoveries have come from the study of ergot. Generally, ergot produces vasoconstriction and psychoactive effects. One of the psychoactive components of ergot fungus is the alkaloid ergine (d-lysergic acid amide), better known as natural LSD. Historically, ergot has been used to control hemorrhage during childbirth, and in 1935 the alkaloid ergonovine was identified and associated with this effect. The alkaloid ergotamine has been used extensively to relieve migraine headaches. Ergot for use in various prescription drugs is grown commercially.

Ergot poisoning ('ergotism') of humans has been implicated in epidemics causing thousands of fatalities in the Middle Ages. Ergot-induced gangrene is called St. Anthony's Fire. One of the reasons for the Salem witch trials is thought to have been abnormal behaviour caused by ergot. It has also been said that the Russian army lost a major battle due to large scale poisoning by rye bread containing ergot while their Turkish opponents were eating
uncontaminated wheat.

Animals may be affected by eating small amounts of ergot over a long period of time, or eating greater quantities in a short period of time. Chronic toxicity by field exposure is the most common scenario with symptoms showing within several weeks of ergot consumption. Ergot may also cause spontaneous abortions in animals.

A related fungus, _C. africana_, causes ergot of sorghum.

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.

Leaf rust, also called brown rust, of wheat is caused by the related fungus _P. triticina_.

Map of US states:
<http://www.census.gov/geo/www/us_regdiv.pdf>

Pictures
_C. purpurea_ fungus:
<http://www.apsnet.org/online/feature/ergot/top.html>
Ergot sclerotia on rye:
<http://botit.botany.wisc.edu/toms_fungi/images/clav1.jpg>
Close-up of ergot sclerotia:
<http://botany.cs.tamu.edu/FLORA/schoepke/sec_ce_2.jpg>
Stripe rust, wheat leaf symptoms:
<http://www.ars.usda.gov/Main/docs.htm?docid=9918&pf=1&cg_id=0>
Leaf rust, wheat leaf symptoms:
<http://www.hgca.com/hgca/wde/IMAGES/brown%20rust1.JPG>

Links
Information on ergot disease:
<http://www.entheology.org/edoto/anmviewer.asp?a=37&z=5>
Ergot and its effects on animals:
<http://vet.purdue.edu/depts/addl/toxic/plant14.htm>
Information on ergot strains:
<http://www2.biomed.cas.cz/~pazouto/purpurea.htm>
Ergotism and the Salem witches:
<http://botit.botany.wisc.edu/toms_fungi/oct99.html>
_C. purpurea_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=162059>
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>
High Plains Integrated Pest Management Guide:
<http://www.highplainsipm.org>
General information on wheat diseases and pathogens:
<http://www.apsnet.org/online/common/names/wheat.asp>.  - Mod.DHA]

[see also in the archive:
Stripe rust, wheat - USA, Australia 20070614.1950
Fungal pathogens, wheat - United Kingdom: new races 20070523.1652
Wheat diseases - USA (KS): crop loss 20070518.1574
Wheat stripe rust, wheat - China 20070413.1230
2005
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Stripe rust, wheat - Australia 20051031.3173
Wheat stripe rust - USA (FL) 20050601.1521
2004
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Wheat stripe rust - Australia (NSW) 20040928.2683
Ergotism, bovine - New Zealand 20040916.2576
Wheat stripe rust - Australia (NSW): alert 20040810.2215
Wheat stripe rust - China 20040429.1191
2003
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Wheat stripe rust, new strains - Australia (SA) 20030930.2465
Wheat stripe rust - Australia (WA) 20030624.1553
Wheat stripe rust, 1st report - USA (Florida) 20030516.1220
2002
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Wheat stripe rust - Australia (Western): alert 20020831.5198
2001
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Wheat stripe rust - USA (Great Plains) 20010715.1366
Wheat stripe rust - USA (Central) 20010629.1236
1999
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Panting syndrome, cattle - Mauritania (02) 19990421.0666
1996
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St Vitus' Dance disease: Correction 19961022.1785]

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