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College of Food, Agricultural, and Environmental Sciences


Tips Help Corn Growers Diagnose Emergence Problems

May 9, 2006

WOOSTER, Ohio -- Corn growers are being encouraged to scout their newly planted corn fields for any emergence problems as a way of quickly identifying solutions and developing successful replant plans, if warranted.

"Diagnosing emergence problems early is critical to the overall performance of the plant," said Pierce Paul, an Ohio State University plant pathologist with the Ohio Agricultural Research and Development Center. "We haven't seen any emergence problems so far in the state and I doubt we'll be anywhere near where we were last year as far as replanting goes, but it's always good to be looking for specific conditions that could be the cause of emergence problems."

Potential corn emergence problems include:

• No seed present, which may be due to mechanical malfunction or bird or rodent damage.

• Plant shoot unfurled and leafing underground. Unfavorable weather conditions, premature exposure to light in cloddy soil, planting too deep, soil compaction, or extended exposure to herbicides under cool, wet conditions could all be contributing factors.

• Poorly developed shoots with brown or yellow tips. Seed rot or seed with low vigor may be to blame. "You want a nice, creamy white root system," said Paul, who also holds an Ohio State University Extension appointment. "Seeds and seedlings that are brown in color, are soft and fall apart easily while digging are obviously dead or dying. Seeds and seedling roots or shoots that have a weft of white to pinkish mold growing on them are likely victims of fungal attack and will likely die."

• Seed has swelled but not sprouted, most often caused by poor seed-to-soil contact or shallow planting.

• Skips associated with discolored and malformed seedlings. Herbicide damage could be the cause.

• Hollow seeds. The condition could be a sign of seed corn maggot or wireworm.

• Uneven emergence. Contributing factors include poor seed-to-soil contact, soil crusting, and soil moisture and temperature variability.

According to the Ohio Agricultural Statistics Service, over 40 percent of the corn crop has been planted, compared to nearly 60 percent this time last year.

"Growers have been reluctant to plant early because of the late wintry weather last spring that caused multiple emergence problems and forced many growers to replant their crop," said Paul. "Despite their worries, we encourage growers to have their crop in the ground by May 10. Corn can still emerge without problems even under unfavorable soil conditions."

Corn can take up to four weeks to emerge when soil conditions are not optimal. This situation was observed last year when corn planted in mid-April did not emerge until the first part of May. In most cases, delayed emergence has no negative impacts on corn yields, as long as stands are not greatly reduced.

Candace Pollock
Pierce Paul