COLUMBUS – Early-planted corn in Ohio is germinating or, in some cases, already emerging. Those signs could indicate that the crop escaped serious disease problems brought about by cold, wet conditions in late April.
However, the plants aren’t out of the woods yet, said Extension specialists at Ohio State and Purdue universities.
“If the weather takes a turn to wet again, even if it warms up, I can see some pretty severe seedling blight diseases developing,” said Pat Lipps, an Ohio State plant pathologist.
Weaker root systems. Growers are concerned about the development of seedling blight diseases – Pythium, for example – which thrive under saturated soil conditions and can kill young seedlings that are slow to germinate in cool conditions.
“We have to remember that corn is a tropical plant. It likes warm weather and grows quicker in warm weather,” Lipps said.
“When you have saturated conditions and the temperatures are cold, the seed may germinate, but the roots don’t grow very much. This leaves an opportunity for fungi to develop and kill the seedlings.”
Pythium is a water mold. It produces swimming spores attracted to sugars “leaked” by seeds and roots.
The spores infect the plant by colonizing the cells of roots and seedling crowns. When the crown of a seedling is colonized, the plant dies.
Other seedling blight diseases, such as Fusarium and Rhizoctonia, function in a similar manner.
Don’t rush to replant. Some corn growers concerned with their early-planted crop might be ready to start over. That could be a mistake, said Bob Nielsen, Purdue Extension corn specialist.
But the recent warmer temperatures will not only hasten the pace of crop development, but will also better enable growers to assess the condition of their early-planted fields.
Patience. Give fields time to visually indicate whether they will recover, Nielsen urged.
Under “normal” circumstances, three to five days after a damage event is sufficient to make this determination, he said.
“This time around, it is requiring closer to 14 days to confidently assess stand health.”
Replanting does not occur without cost. Replant expenses – including seed, fuel, herbicide, labor, etc. – easily can outweigh the uncertain value and an uncertain yield gain, and can reduce a grower’s net dollar return.
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