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Date: Tue 16 Jun 2009
Source: Country Guide, Western Edition [edited] <http://www.country-guide.ca/West/issues/ISArticle.asp?aid=1000331067&PC=FBC&issue=06162009>

Fusarium also becoming oat growers' problem

Fusarium head blight [FHB], a fungal disease commonly linked to barley and wheat, is "indeed a problem" in Canada's commercial oat fields, a new study shows. "You don't see it in oats as you do in barley or wheat, where the disease is quite obvious in-season," plant pathologist Andy Tekauz said in a release from the Western Grains Research Foundation (WGRF). "So the likely assumption in the past was that oats weren't affected by fusarium."

The WGRF backed a 3-year project. Tekauz was able to demonstrate FHB is "indeed a problem in commercial oat fields, with more than 75 percent of the fields surveyed annually affected." Out of the seed taken from the sample fields, Tekauz said he could isolate fusarium fungi from 10 to 15 percent. Fusarium can be found in most Manitoba oat fields, he said, and it "tends to be more of a problem in the eastern Prairies and becomes less of a problem as you move further west."

Unlike wheat, however, in which "95 percent of the problem" is caused by the species _F. graminearum_, infections in oats involve the same
4 species infecting barley crops: _F. graminearum_, _F. poae_, _F.
sporotrichioides_ and _F. avenaceum_, Tekauz said. "Their proportion tends to change from year to year. So environment or other factors play a role in determining what levels of these fungi will be found on the seed."

Canadian oat varieties and breeding lines, plus material from elsewhere, were then tested for genetic resistance. "Among Canadian oats, there was variability in FHB resistance. We were also able to identify genetic resistance in lines obtained from other countries, particularly South America," Tekauz said. Looking for resistance to FHB based on low accumulation of DON (deoxynivalenol, a mycotoxin) is now a "goal and priority" in Canadian oat breeding programs, the WGRF said. Generally, Tekauz said, oats tend to be more resistant than barley or wheat to fusarium.

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[Fusarium head blight (FHB; also called scab) on wheat is caused by several fungal species originally classed into the genus _Fusarium_, accounting for the common name of this disease. Current names of the fungi mentioned above are _Gibberella zeae_ (previously _Fusarium graminearum_), _Fusarium poae_, _Fusarium sporotrichioides_, and _Gibberella avenacea_ (previously _Fusarium avenaceum_).

FHB causes yield losses of up to 45 percent in small grain crops and reduces the grade of harvested grain. It may also contaminate the grain with fungal toxins, for example DON (also called vomitoxin), which can affect stock and may lead to reduced feed consumption or feed refusal. The total crop may be lost if grain is rejected because of toxin levels. Disease management includes timely fungicide applications and crop varieties with reduced susceptibility.

The scab fungi decompose organic host matter remaining on the soil surface. Minimum tillage practices, which are becoming more widely used in cereal growing areas have contributed to the increase of inoculum and scab emerged as an important disease of crop species previously considered as non-hosts. In 1999 in the south of Brazil, an FHB epidemic was reported for the 1st time on oats.

Maps of Canada:
<http://www.lib.utexas.edu/maps/americas/canada_pol_1986.gif> and <http://healthmap.org/r/007x>

Pictures of FHB symptoms
On oat plant:
<http://www.fao.org/docrep/008/y5765e/y5765e24.jpg>
On oat seedhead and grains:
<http://www.cropdiseasescouncil.ca/image/diseases/fhb-oat.jpg>  and
<http://www.grainscanada.gc.ca/str-rst/fusarium/images/photo-oats-avoine.jpg>
On wheat:
<http://www.nwroc.umn.edu/Cropping_Issues/2005/issue6/FHB_examples.jpg> and <http://plantsci.sdstate.edu/planthealth/other_images/scab.jpg>

Links
FHB information:
<http://www.agriculture.gov.sk.ca/Default.aspx?DN=24a3bb18-a096-4bcd-889c-b1e2c94a03e9>,
<http://www.hgca.com/hgca/wde/diseases/Foliarfus/Sdfuhost.html>,
<http://www.grainscanada.gc.ca/str-rst/fusarium/fhbwc-foc-eng.htm>
(with pictures),
<http://www.apsnet.org/education/feature/FHB/>,  and <http://smallgrains.psu.edu/pdf/FusariumHeadBlight.pdf>
FHB disease and toxin information:
<http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex92>
FHB and mycotoxins in oats:
<http://www.gov.mb.ca/agriculture/research/ardi/projects/00-443.html>,
<http://www.fao.org/docrep/008/y5765e/y5765e0g.htm>,  and
<http://cat.inist.fr/?aModele=afficheN&cpsidt=19886421>
_F. graminearum_ current species complex and FHB information:
<http://www.ars.usda.gov/Main/docs.htm?docid=9821>
Taxonomy and synonyms for all fungal pathogens via:
<http://www.indexfungorum.org/Names/Names.asp>.  - Mod.DHA]