July 30, 2005
Source: GrandForksHerald.com, 23 Jul 2005 [edited] <http://www.grandforks.com/mld/grandforks/news/12207479.htm>

Crop diseases like scab and root rot, which thrive in wet weather, are showing up in North Dakota after heavy rain.

Farmers and crop scouts have found Fusarium head blight, or scab, in wheat and barley fields in the Red River Valley and other parts of North Dakota, said Marcia McMullen, a plant pathologist at North Dakota State University. Scab is a fungal disease that robs small-grain crops of yield and quality.

"I think it's going to be even a bigger problem than we ever want to think about," McMullen said. Red River Valley farmers said some of their sugar beets are infected with root rot diseases. "We're seeing a lot of it," said Tom Knudsen, an agronomist at the Wahpeton-based Mann-Dark Farmers Cooperative.

The amount of damage caused by root rot and other diseases is unknown because many crops are still developing, officials said. But Knudsen estimates Mann-Dark's growers will lose about 40 percent of this year's
[2005] crop to flooding.

Some of the co-op's sugar beet fields have received as many as 20 inches of rain through June 2005. Southern Richland County has been hit especially hard, he said. In other parts of North Dakota, farmers have been battling
hail damage.

Clay County (Minnesota) farmer Mark SyQuest said storms dumped 11 inches on his farmland in June 2005, damaging some crops and spurring the onset of some scab in his wheat.

Last week [2nd week July 2005], NODS field scouts found small infestations of scab in 36 of 103 wheat fields throughout the state, including some in the Red River Valley, McMullen said. "I think it's going to get pretty
bad," she said. The region's farmers have seen little of scab since 2001.

In an 8-year stretch, from 1993 until 2001, North Dakota's economy lost an estimated USD 3.5 billion to scab outbreaks. During the same period, scab cost Minnesota about USD 1.8 billion in crop losses, an NODS study
completed last year [2004] shows.

David Karnes, a farmer in Clay County, and other farmers have watched their early optimism dissipate and are disappointed, to say the least.

--
ProMED-mail
<promed@promedmail.org>

[Fusarium head blight (FHB), also known as scab or tombstone, is a disease of wheat, barley, oats and other small cereal grains and corn. It is caused by several _Fusarium_ species , primarily _F. graminearum_. FHB causes severe production losses worldwide and may be as high as 50 percent. It is a major cereal disease in Manitoba, Saskatchewan and Alberta. Scab can cause significant yield and quality damage, as well as toxicoses in animals and humans. Damage due to scab in the United States was estimated to be more than USD one billion in 1993 and USD 500 million in 1994. In China, the estimate is that scab may affect up to 7 million ha, and 2.5 million tons of grain may be lost in epidemic years. Diseases related to fusarial mycotoxin in humans have been reported in China, India and Japan, whereas in animals, diseases have been reported in numerous parts of the world.

FHB-infected kernels often contain a mycotoxin called deoxynivalenol (DON), also known as vomitoxin. It is a very mild mycotoxin. When present at high enough levels in the diet (>2 ppm), it causes a reduced feed intake in swine. DON is of limited concern to cattle producers because it is metabolized extensively in the rumen. DON belongs to a family of mycotoxins called tricothecenes. Tricothecenes are protein inhibitors, and it has been
speculated that animals fed high levels of tricothecenes may have a weakened immune system. However, DON is a very mild toxin compared to other tricothecenes. It is also extensively metabolized, poorly absorbed and
rapidly cleared from tissues and fluids in ruminants. There is no evidence to support depressed immune function, even in pigs, which are much more sensitive to DON.

Links:
<http://www.fao.org/documents/show_cdr.asp?url_file=/DOCREP/006/Y4011E/y4011e0j.htm>
<http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex92?opendocument>
<http://www.engormix.com/e_articles_view.asp?art=91>
<http://res2.agr.ca/ecorc/fusarium01/cont_e.htm>
<http://www.ext.nodak.edu/extpubs/plantsci/smgrains/pp804w.htm>
<http://www.cdl.umn.edu/special_rpts/mcvey/McVey.html>
- Mod.DH]

[see also in the archive:
Wheat diseases - India 20050615.1683
2004
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Fusarium graminearum, soybean - Argentina 20040215.0493
2002
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Fusarium head blight, oats - Canada (Manitoba) 20021017.5573 2001
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Fusarium head blight, wheat - USA (Michigan) 20010725.1452
2000
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Fusarium head blight: biological control 20000824.1416
Fusarium head blight, cereal - Canada (Manitoba) 20000823.1405 Fusarium head blight fungicide approved - Canada 20000624.1038 1999
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Scab-resistant wheat, McVey cultivar - USA 19990801.1311
Scab disease, wheat - Canada, USA 19990508.0756]