.

Date: 22 Sep 2007
Source: Susan Baekeland <grolleyog@wanadoo.fr>

I have been noticing more and more maize fields with an infection, whole fields are just brown, with the plants standing, but they are dry. The problem with this diseased maize is that it is drying off prematurely. It is not spotted and the cobs do not look rotten. Here the wheat harvest was well down due to the rain, and straw and hay are in short supply. The maize here is about 2/3 used for silage for winter feed for cattle, and 1/3 for sale in kernels. These dry plants will not make proper silage.

We visited a couple of farms and spoke to the farmers. The outcome is: there is a lot of it about; we have the same disease here in the wheat; they should have sprayed against it in the spring; the local name is 'fusariose', both in maize and wheat. The farmers attribute the outbreaks to plant 'stress' caused by too much rain and then the best part of 7 weeks with no rain.

The infection is caused by one of the 26 isolates of the mycotoxin-producing _Fusarium_. This infects the roots and the epidermis, etc., of the plant. (Reference: 'Impact of the exodermis on infection of roots by _Fusarium culmorum_. Susan A Kamula, Carol A Peterson, Colin I Mayfield. Dept of Biology, University of Waterloo, ON. Canada.) I think there is a good chance we are looking at an infection by _Fusarium culmorum_.

I would say it was much more widespread than in southern Normandy, but I have not been out of the area.

--
Susan Baekeland
Veterinarian
La Meute du Ruisseau,
Le Ruisseau,
50240, Carnet
St James, Normandy, France
<grolleyog@wanadoo.fr>

[Thank you very much to Ms Baekeland for supplying this report.

Several species of the soil- and residue-borne fungal genus _Fusarium_ are causing a number of head blight, stalk rot, seedling root rot, and ear and stalk rot diseases in grain crops such as maize, wheat, barley, rye, and oats. In parts of northern Europe, _F. culmorum_ and _F. avenaceum_ are the prevalent pathogens. These fungi persist and multiply on infected crop residues. During moist weather, spores of the fungi are windblown or splashed onto the heads of cereal crops. Stress conditions and lesions caused by other fungi or insects are known to increase susceptibility of host plants to _Fusarium_.

_F. culmorum_ infection is thought to be monocyclic. Infection of ears is optimal during the period of flowering when fungal spores may land on the exposed anthers and enter the host. The resistance of ears to infection will have increased significantly by the time secondary inoculum is produced. Therefore, fungicide sprays applied late in the crop cycle are unlikely to be of significant benefit.

_Fusarium_ species are capable of producing mycotoxins, which can seriously affect livestock and humans. For any given host species, only certain strains develop toxins. In cereals, mycotoxin contamination is most commonly associated with _F. graminearum_, _F. culmorum_, _F. avenaceum_, and _F. poae_. Zearalenone is a mycotoxin produced by several fungi, including _F. culmorum_ in maize and wheat. The issues associated with _Fusarium_ infections can be reduced through the use of integrated crop management techniques such as avoiding growing cereals after maize, deep plowing rather than minimum tillage, choosing a variety with some resistance to the pathogens and, where appropriate, the use of a suitable azole fungicide.

In the report above, the description of the cobs not showing any signs of rot is somewhat confusing. Maize plants infected with _F. culmorum_ would be expected to show some ear symptoms. However, when the crop is nearing maturity and cobs have largely dried off, early fungal damage may be less obvious. We would be grateful for any further information on the situation.

Map of France:
<http://worldatlas.com/webimage/countrys/europe/lgcolor/frcolor.htm>

Pictures
_Fusarium_ symptoms on maize ear:
<http://www.ent.iastate.edu/imagegal/plantpath/corn/fusarium/fusarium_insect_inj.html>
Pictures of assorted maize diseases and pathogens:
<http://lubbock.tamu.edu/cornIPM/DiseaseImages/index.html>

Links
_Fusarium_ diseases of small grains:
<http://www.apsnet.org/online/feature/FHB/Top.html>  and <http://www.ag.ndsu.edu/pubs/plantsci/smgrains/pp804w.htm>
_F. culmorum_ mycotoxin chemotypes:
<http://www.hgca.com/publications/documents/cropresearch/UK_pathogen_survey_NIAB_2007.pdf>
_F. culmorum_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=196997>
_F. graminearum_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=200256>
Genus _Fusarium_ list of species and taxonomy via:
<http://www.indexfungorum.org/Names/Names.asp>
List of maize pathogens:
<http://www.apsnet.org/online/common/names/corn.asp>.
- Mod.DHA]


[see also in the archive:
Southern rust & ear rots, maize - USA 20070918.3096 Fungal blights, wheat, corn & chickpea - USA (NB, MT) 20070621.2000
2005
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Fusarium head blight, wheat - USA (MN, ND) 20050812.2366 2000
----
Mycotoxins: a review 20001130.2089
Fusarium head blight: biological control 20000824.1416 Fusarium head blight, cereal - Canada (Manitoba) 20000823.1405]

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