Hot, dry weather led to uneven emergence

Corn growers finding marginal stands in their corn fields might be seeing the effects of record rainfall in 2011, a mild winter in 2012 and continued hot, dry weather — all of which potentially are contributing to problems with corn emergence.

Multiple northern Ohio cornfields have had fair to poor stands, according to Steve Prochaska, an Ohio State University Extension educator in north-central Ohio, and member of the university’s Agronomic Crops Team. Stands in those fields ranged from 14,000 to greater than 28,000 plants per acre, he said, noting that the losses are variable and are likely related to the record rainfall last year, combined with the mild winter and early, hot spring the region has experienced in recent months.

“Surface crusting and soil compaction were evident in the fields, as well as soil compaction zone about 2 to 4 inches from the surface,” Prochaska said. “Likewise, corn seminal roots of emerged plants were observed growing laterally along the top of the compaction zone. This may have been exacerbated by the early planting some growers did in the first week of April.

“Corn has been slow to emerge. In some cases it has taken as long as three weeks, and was exposed to the wet weather conditions.”

The problem is that the hot, dry weather has created some of the soil crusting conditions that makes it hard for emerging corn to get out of the ground, said Peter Thomison, an OSU Extension agronomist. The heat is also causing uneven growth and even some mortality.

“It’s a big topic among growers,” Thomison said. “The hot dry weather has had a significant effect, not only in Ohio but in other states including Iowa and Illinois, where poor root development has caused floppy corn where corn has fallen over.”

Prochaska said other possible factors contributing to corn stand loss include:

* Limited rotations without wheat or forage and in some cases multiple-year soybeans now followed by corn.

* Organic matter of soils in some areas of the fields was less than 2% with a corresponding low cation exchange capacity, or CEC, which may be more prone to crusting and compaction.

* Use of pop-up fertilizer applied on corn seed at planting.

* Herbicide injury. Products containing cell growth inhibitors may, under certain environmental conditions, injure corn seedlings.

* Insect injury from a number of insects including wireworms, seed corn maggots and grubs. All have the ability to reduce plant stands.

* Corn seedling diseases caused by various pathogens.

* Malfunctioning corn planter over seedling depth and fertilizer delivery.

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