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Serving: IA
Iowa Corn & Soybean Crops Are Moving Rapidly Toward Maturity

Iowa Corn & Soybean Crops Are Moving Rapidly Toward Maturity

Extended period of dry and hot weather the past week or so has helped corn and soybeans progress rapidly toward maturity. Weekly USDA survey released August 30 shows 8% of Iowa's 2010 corn crop has already reached maturity.

Corn and soybeans throughout Iowa progressed rapidly toward maturity this past week. "The extended period of dry and hot weather has helped crops move along," notes Harry Hillaker, state climatologist with the Iowa Department of Agriculture. "Western Iowa received light rain showers last week, while a majority of the state was dry. For much of Iowa, the past week was the longest span without rain during the 2010 growing season."

The weekly weather and crop conditions survey released August 30 by the Iowa office of USDA's National Ag Statistics Service shows 8% of Iowa's corn crop has already reached maturity. It shows 77% of the crop has started to dent, and 94% has entered or reached dough stage. Corn condition has improved slightly with 69% of the state's crop now rating "good to excellent."

Soybeans as of August 30 have begun to drop their leaves in some fields. Pods have now been set on virtually all of the state's soybean acres, and 14% of Iowa's soybean acres have turned color--which is ahead of last year's 4% and the 5-year average of 13% at the end of August. Soybean condition statewide for this year's crop is rated 69% "good to excellent" as of August 30.

About 8% of this year's Iowa corn crop has now reached maturity

The complete report is available on the Iowa Department of Agriculture's site at and on USDA's site at

Kevin Ross, a farmer from Minden in Pottawattamie County in southwestern Iowa says corn and soybean crops look good in his area just outside Council Bluffs in the hills. "There are some farmers around home who are itching to get in the field this week to pick a little high moisture corn which they feed. I don't know what their preliminary yields are, but overall, things look pretty good around my area."

He adds, however, "I have to say I'm glad I'm not farming land in the Missouri River bottoms this year. That's because the yields are going to be pretty tough in those areas. With a lot of rain they have drowned out places in fields and fields in those areas have generally really been crippled."

Corn harvest in much of Iowa will be here before you know it

Is the corn in his area maturing rapidly now, as it is in other parts of the state? "Yes," says Ross. "We've had hot, dry weather recently and the dry breezes really matured the corn and have helped dry it down in the field. Corn harvest is going to be here before we know it. I think you'll see some farmers getting in to begin harvesting their fields in a big way soon."

Driving from southeast Iowa to the Farm Progress Show site at Boone in central Iowa yesterday, farmer John Kinnick of Davis County saw a lot of soybean fields with dead and dying areas due to Sudden Death Syndrome. He notes that the corn crop also seems to be maturing quite rapidly.

Roger Elmore, Iowa State University Extension agronomist, says top die back and other issues on corn plants in the past week have changed the maturity of the crop dramatically. He says there are some yield concerns with this rapid maturity of the corn plants.

Expect to see lighter kernel weights and lighter test weights this fall

"If you think back to the heat we had in July and August, that really speeded up crop development," says Elmore. "It pushed the corn to an earlier maturity date than we had last year for certain, and probably for the last several years. That's not positive for yields, in my view. I would guess we're going to have lighter kernel weights and possibly lighter test weights because of that."

What should corn growers do as they approach harvest? Last year some farmers waited almost too long and didn't end up harvesting some of their corn fields until this spring. "The earlier maturity we are seeing right now is a positive, if you are looking for a silver lining in this situation," says Elmore. "We'll have corn reaching black layer stage earlier than normal, and in fact some of that is occurring this week in some fields across the state."

He adds, "This situation gives us the whole month of September for the corn to dry down in the field. We have longer and warmer days in September, normally, than we do in October in Iowa. Last year the cooler than normal weather conditions dragged corn maturity out to the end of September. We had a frost after that and then we had cool damp weather during October and also November in Iowa. It doesn't look like that will happen this year."

How will this year's corn respond to continued heat in September?

The genetics of corn hybrids have been improved in the past 5 to 10 years. Will the potential yield loss from this rapid dry down of corn in the field in late August and early September of 2010 be minor--given that the genetics have improved? "Probably not," says Elmore. "The improvement in genetics hasn't been clear, in terms of increasing yields. We're seeing about a 2 bushels per acre per year increase in the average corn yield. So for the past five years, that means we're talking about a 10 bushel per acre increase in yield potential over that period."

He adds, "I don't think that the physiology of the plant has changed to the point where the warmer weather we experienced this summer in July and during the seed filling period in August would change the ability of today's modern corn hybrid to respond differently. Certainly, corn yields today will be higher this year than if you had a 10 year old hybrid to compare it to. But I think yields this year will still be hampered by the heat and fast-paced movement of the corn crop toward maturity that we are experiencing."

With 77% of Iowa's 2010 corn crop having reached dent stage and 8% of the crop already reaching maturity as of August 30, Elmore's observation is "This means the Iowa crop is now almost mature. So if we get continued heat in September it will speed up the dry down rate of the corn grain in the field, but it won't necessarily further reduce yield."

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