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Around the County

Frequent information updates for agricultural audiences

Corn Ear Rots - from Mike Roegge

Posted by John Fulton -

The weather this year has done more than just delay the maturity of the corn and soybean crop, it has also allowed crop diseases to prosper. In corn, it's not too difficult to find leaf rust, grey leaf spot, northern corn leaf blight, and anthracnose. In addition, ear rots are not uncommon: diplodia and penicillium can be found and fusarium might be present as well. It's doubtful that aspergillus (which can cause aflatoxin) will be present since dry, hot conditions are usually necessary.

Diplodia will cause the ear and kernels to prematurely die, in which case the kernels will be so light they'll not contribute to yield. It's easily identified by the whitish colored mold growing in and among the kernels on the ear. Oftentimes, you'll note the husk will die much earlier than the rest of the plant. Diplodia if oftentimes much worse in continuous corn and when rainfall occurs during pollination. We saw some diplodia last year, but this year we may see more. The only good thing about this disease is that it doesn't produce toxins.

Penicillium can be found in some fields as well. Usually this will occur when the tip of the husk has been exposed, either by the cob extending out through it, or through bird or insect damage. The key symptom of this ear rot would be the bluish/ green mold growing between and on the kernels. This rot may or may not cause toxins. We've seen a number of fields this year in which birds sought out corn during the milk stage to feed on kernels. I think this is the most widespread I've seen bird damage. Ordinarily birds damage ears of corn to get at the insects that are present. That wasn't the case this year as the birds found they could consume the kernels and did so. And in most cases, they didn't really consume many kernels per ear, but numerous visits sometimes caused quite a few ears to be affected. . In doing so, they opened up the ear tip to allow moisture and molds to enter. The high humidities and plentiful rains of August did the rest.

Fusarium ear rot may be the other disease we see this year. Unlike the above two ear rots, I've not seen fusarium yet this year. But like aspergillus, this disease is favored by hot, dry conditions at pollination (so we may escape this particular ear rot). This rot can also produce toxins. Look for orange/pink colored fungal growth.

With all these diseases, the important factor is to get the corn harvested and dried to a moisture content of 15% or below as quickly as possible. Remember that if the bin averages 15% moisture, there will be spots above that. If you plan on keeping the grain, closely monitor the bin for moisture and temperature. If you plan on feeding it, have it tested for toxins. Keep the combine fan speed up to blow out lightweight, fungus infected kernels.

One last thought, I'm wondering if the bird predation we saw this year might be something we will witness regularly in the future. The reason being that the birds have now found out that corn (at milk stage) will satisfy their food needs. Will they be back?



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