Rain pummels new corn and stops growers from planting or replanting

COLUMBUS – If farmers planted their corn before recent thunderstorms pelted the fields, they were luckier than those who still can’t get into their fields.

Right?

Maybe, says Ohio State University Extension agronomist Peter Thomison.

It depends. Saturated soils and ponding of some fields – localized for much of Ohio – raise questions as to the crop’s condition the crop is headed..

Thomison said oxygen depletion caused by flooded conditions can impair nutrient and water uptake and inhibit root growth.

How bad is it? The extent to which flooding injures corn is determined by several factors including plant stage of development when flooding occurs, duration of flooding and air/soil temperatures.

When you have warm temperatures (above 77 degrees Fahrenheit), corn may not even survive 24 hours, Thomison said.

Hidden problems. Even if the plants survive flooded conditions, there could be problems later in the growing season.

Excess moisture during the early vegetative stages retards corn root development, Thomison said.

As a result, plants may be subject to greater injury during a dry summer because root systems are not sufficiently developed to access available subsoil water.

About 85 percent of the corn has been planted in Ohio, with areas mainly in the north central and northeast regions of the state still waiting to plant.

Planting window closes. Thomison said growers can usually plant corn up through the first week of June, at which time they are encouraged to switch to another crop, like soybeans.

If growers are in a late-planting or replant situation, they may want to take a look at Bt corn hybrids, Thomison said, if the right hybrid maturity is available.

Late-planted fields are more susceptible to second generation damage from corn borer.

Walk those fields. Growers are dealing with saturated soil conditions in their fields should take at look at the regrowth that is occurring.

Cut the plant open and look at the growing point. If it’s dark and mushy, it’s likely the plant will either die or be unproductive, Thomison said.

Sometimes when a plant sits in a saturated condition for prolonged periods, the growing point of the plant dies, but you get suckers that grow from the growing point below-ground nodes.

“I’ve never seen a normal ear develop from a sucker,” Thomison said.

Disease problems. Disease problems that become greater risks due to flooding and cool temperatures include pythium, corn smut, and crazy top.

Despite fungicide seed treatments, pythium root rot contributed to serious stand reductions in many Ohio corn fields last year, Thomison said.

There is limited hybrid resistance to these diseases and predicting damage from corn smut and crazy top is difficult until later in the growing season.