Iowa's corn and soybean crops are beginning to mature, but they are running significantly behind normal development, according to the weekly crop and weather survey released September 2.
The Iowa Ag Statistics Service, the government agency that conducts the survey, says the amount of corn at or beyond the milk stage has progressed to 93%, two weeks behind last year and 11 days behind the 5-year average. About 33% of the corn crop is at or beyond dent stage, behind the normal average of 64% for this date.
Lateness of crop is concern
Soybeans setting pods have progressed to 95%, two weeks later than last year and the 5-year average. About 9% of the soybeans are turning color, well behind last year's 26% pace and the 5-year average of 23%.
Corn condition is rated 48% good and 15% excellent. The state's soybean crop is 48% good and 14% excellent. The state's hay crop is two weeks behind the 5-year average, with the third cutting of alfalfa at 50% complete. All hay is rated 40% good and 8% excellent.
Although August rainfall was only about half the normal 4.19 inches, most of the state has adequate topsoil and subsoil moisture, says Harry Hillaker, state climatologist at the Iowa Department of Agriculture.
Aphids still bugging Iowa beans
Each week Iowa State University Extension crop specialists from around the state hold a telephone conference to discuss what's happening across Iowa. This week soybean aphids were again one of the topics. "This insect pest has been a continuing issue across the state this summer," says ISU Extension weed specialist Mike Owen, who coordinates the weekly conference call.
The soybeans that were planted in reasonable time last spring have now generally entered the R5 and R6 stage of development. ISU entomologists Matt O'Neal and Marlin Rice suggest that in these later stages of soybean growth, spraying for aphids isn't going to be very helpful.
But this year Iowa has a lot of later planted soybeans that aren't as mature entering September. Aphids are still an issue in some of these fields. The question is "Should I invest in spraying for those aphids?" That depends on what you think the weather is going to do and when will you get the crop harvested.
Corn yellow, running out of N
More corn plants are turning yellow entering September, as corn is running out of nitrogen. "Particularly where nitrogen fertilizer was applied in the fall for the 2008 crop, we are now starting to see nitrogen stress in the corn. It is running out of N," notes Owen.
Hopefully, the first killing frost won't hit early this fall. Iowa needs a later than normal frost so that the latest maturing corn and soybeans can reach maturity.
"We are also seeing some other issues developing, such as blunt ear syndrome in certain genetic hybrids whose corn ears aren't developing like they should," says Owen. "We really don't know what is the cause of this, but it's pretty widely spread across the Midwest this year. It could be genetics or environment. But it is a real problem."
Diseases and weeds moving in
"We are also seeing a number of diseases in corn and beans in early September this year," says Owen. "And we did lose some nitrogen with all the rain earlier this spring and in June--and that yellow corn we now see showing up in fields is a symptom of the nitrogen loss."
On the knolls and hilltops of soybean fields, the leaves of soybean plants are beginning to turn yellow and drop off. A lot of that has to do with diseases.
"My concern is weeds, since I'm a weed specialist," says Owen. "Those wet holes that were flooded in fields are really allowing a lot of weeds to grow this year. Farmers need to be look at those spots in fields when harvesting the crop this fall. Be sure you make adjustments with your management in 2009 for that increased weed population."