GIBBERELLA EAR ROT, MAIZE

Grahame Jackson

Sydney NSW, Australia

For your information

2021-02-16T22:19:00.0000000Z

GIBBERELLA EAR ROT, MAIZE - USA: (OHIO)

ProMED
https://promedmail.org/

Source: Urbana Daily Citizen [abridged, edited]
https://www.urbanacitizen.com/news/79274/some-ohio-corn-showing-signs-of-ear-rots
If you had damaged corn or were rejected at an elevator because your vomitoxin levels were too high, you are not alone. This was a widespread issue across Ohio. Vomitoxin is [due to] _Gibberella_ ear rot. Like with most ear rots, there have not been clear results on management strategies. Harvesting early is very important, getting the grain cooled down and dry can stop the spread. Some hybrids are more resistant than others, but this often is not indicated. Some fungicide studies have been conducted but it has been difficult to draw conclusions. Traditional aerial applications are not as effective because the fungicide needs to reach the silks [fiber bundles at the top of ears - Mod.DHA]. Drop nozzles to the silking level were the most effective.

There are 4 different ear rots common in Ohio: _Fusarium_, _Gibberella_, _Diplodia_, and _Trichoderma_. _Gibberella_ is the only one that produces vomitoxin. This is confusing because fusarium head blight (scab) can produce vomitoxin in wheat. _Fusarium_ in corn produces fumonisin which can be toxic, especially to horses. [For] _Diplodia_, no known mycotoxins are associated with disease. [For] _Trichoderma_, mycotoxins are generally not a major concern. While these 3 do not produce vomitoxin, they can reduce yield and weight so it is still important to prevent occurrences. Crop rotation is encouraged, burying residue can reduce inoculum that survives through the winter.

[Byline: Amanda Douridas]
--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[Several species of fungi originally classified in the genus _Fusarium_ are causing a number of diseases or disease complexes in grain crops. The diseases include head blights, stalk rots, seedling root rots, and ear rots of wheat, maize, barley, rye, oats, and other crops. Pathogens affecting these hosts may be different phylogenetic species or strains which are often limited to particular regions of the world. While some of the pathogens have now been re-classified into different genera, the associated diseases are often still collectively referred to as 'fusarium diseases'.

For maize, _Gibberella zeae_ (previously _Fusarium graminearum_) causes an ear rot ("red" ear rot), but other fungi from the 'fusarium disease' group may be responsible for different ear, stalk, and kernel rots. Maize ear rots are often associated with insect damage to ears or kernels which provides easy entrance points for the fungi.

Depending on the fungal species or strains involved, as well as on environmental factors during plant growth and grain storage, fusarium diseases may also contaminate the grain with mycotoxins, for example DON (deoxynivalenol, also called vomitoxin), which can seriously affect livestock. The total crop may be lost if grain is rejected because of toxin levels. The fungi persist and multiply on infected crop residues. During moist conditions, 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. Disease management generally includes timely fungicide applications, crop rotation with non-hosts and crop varieties with reduced susceptibility. Use of certified clean seeds is essential.

New fungal strains are emerging worldwide. The re-emergence of some fusarium diseases is thought to be driven mainly by changes to climate and agronomic practices (see for example, ProMED post 20100726.2497). In Canada, the emergence of a new fusarium head blight (FHB) strain of wheat with increased mycotoxin levels has been reported (ProMED post 20091210.4211). Continuing breeding programmes for new resistant (or tolerant) crop varieties are needed to stay ahead of pathogen evolution.

Maps
USA:
https://www.mapsofworld.com/usa/large-us-map.html and
http://healthmap.org/promed/p/237
Individual states via:
http://www.mapsofworld.com/usa/usa-state-and-capital-map.html

Pictures
Ear rot symptoms on maize:
https://www.ent.iastate.edu/images/plantpath/corn/fusarium/fusarium_insect_inj.jpg,
http://farm5.static.flickr.com/4074/4910982623_9af03e37ab.jpg, and
http://farm5.static.flickr.com/4137/4910983061_a7e22b3c11.jpg
Comparison of different maize ear rots:
http://www.beckshybrids.com/Portals/0/SiteContent/Becks-Blog/Steve/Becks_Corn_Disease_Comparison.png and
https://d31029zd06w0t6.cloudfront.net/wp-content/uploads/sites/36/2021/02/web1_CornWoes.jpg
Fusarium disease on maize seedling:
http://farm6.static.flickr.com/5095/5427580172_281af25dcf.jpg

Links
Gibberella ear rot and other fusarium diseases in maize:
http://www.thompsonslimited.com/2015/09/03/gibberella-ear-rot-in-corn/,
https://www.farmersweekly.co.za/farm-basics/how-to-crop/dealing-with-gibberella-ear-rot/,
https://www.extension.purdue.edu/extmedia/BP/BP-77-W.pdf, and
http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0016/113623/fusarium-cob-rot-of-corn.pdf
Gibberella ear rot, disease cycle:
https://www.pioneer.com/CMRoot/pioneer/US/images/agronomy/library_corn/diseases/ear_rot/gibberella_ear_rot_disease_cycle.jpg
Mycotoxins in maize:
http://www.fao.org/docrep/X2100T/X2100T05.HTM
Fungal taxonomy and synonyms via:
http://www.indexfungorum.org/Names/Names.asp
- Mod.DHA]

GIBBERELLA EAR ROT, MAIZE - USA: (OHIO)

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