sealPurdue News

September 13, 2002

Purdue experts: Harvest wetter to avoid more yield loss

WEST LAFAYETTE, Ind. – In a year of extreme weather patterns, Purdue University agronomists advise farmers to harvest their grain wetter than usual.

Drought conditions have severely stressed much of the corn crop in many parts of Indiana, causing stalks to weaken and some plants to die prematurely. In order to avoid additional problems, agronomists say this may be the year to harvest the crop at a higher grain moisture content than normal and pay to dry the corn crop with grain dryers.

"The risk of further stalk damage and yield loss while crops are allowed to dry in the field may offset the additional expense of mechanical drying this fall, particularly when corn prices are about $1 per bushel higher than one year ago," said Tony Vyn, professor of agronomy.

Indiana farmers typically harvest corn at 15 percent to 20 percent moisture content – that's after the corn has had time to dry from 30 percent moisture at maturity, Vyn said. Under normal conditions, crops usually dry about 0.5 percent per day.

"This year we suggest harvesting corn at about 25 percent moisture," Vyn said. "That will help minimize yield loss due to corn stalk lodging and ears dropping to the ground."

Vyn said the stalks are weak because dry weather late in the growing season caused the plants to transfer material from the stalks to the developing ears. Weak stalks tend to lodge, or fall over, and also are prone to stalk rot disease.

"You can test to see how weak the corn stalks are by pushing against them," he said. "Harvest those fields first that are prone to lodging."

Weakened roots from soil compaction, typical of a crop planted under wet conditions like those found last spring, also contribute to lodging and stalk rot.

Extension agronomist Bob Nielsen said projected corn yields are already down due to various stresses, and harvesting wet may protect from further mechanical harvest losses.

"The key is that farmers can harvest corn that is wetter than normal without a lot of machine damage to the kernels," he said. "The downside to waiting is that you might lose everything on the ground if stalk rot sets in."

It's dry now, but should the rains return, new problems can occur.

"Last fall, harvest was interrupted by a rainy October," Nielsen said. "When farmers got back in the fields in November, stalk rot had set in."

In some of the drier regions of Indiana, the corn harvest is already under way.

"There's a sense of urgency about this year's harvest," Vyn said. "In pockets around the state there are some good crops, but for many farmers, the sense is that they better get their crop out of the field while they can in order to prevent any additional yield losses."

In addition to the corn crop, soybeans stressed by drought are dying prematurely and should also be harvested early.

Vyn said stressed soybeans are at risk of pod shattering.

"It varies by variety, but the heat and dry weather during the pod filling stage stresses the plants, making it more likely that the seed pods will break, dropping the seeds to the ground," Vyn said.

"Due to delayed planting, and this summer's dry conditions, many soybean fields will mature late and have a great deal of seed moisture and yield variability to them. I suggest farmers try to harvest the most mature fields first, even if that means harvesting only partial fields and leaving the less mature areas for later harvesting."

For other harvest related information, check out Purdue Extension's Harvest 2002 Web site.

Writer: Beth Forbes, (765) 494-2722;

Sources: Tony Vyn, (765) 496-3757;

Bob Nielsen, (765) 494-4802;

Related Web sites:

Bob Nielsen's Chat 'n Chew Café corn information Web site

Purdue News Service: (765) 494-2096;

* To the Purdue News and Photos Page