Iowa's corn crop has advanced to 23% reaching maturity, 17 days later than last year and 2 weeks behind the 5-year average. Thus, nearly one fourth of the state's corn has now reached maturity and is safe from frost.
That's what the weekly crops and weather survey shows, based on results released by Iowa Ag Statistics Service on September 22. Corn condition is rated 61% good to excellent, according to the government survey.
"The warm dry weather that much of the state enjoyed last week was great for continued crop development and was very much needed as both corn and soybeans remain behind normal maturity," says Harry Hillaker, state climatologist at the Iowa Department of Agriculture. "Crops in Iowa continue to look pretty good, but the longer we are able to avoid a frost, the better."
Beans are week or more behind
About 43% of the soybeans are dropping leaves, 32% behind last year and 30% points behind the 5-year average. Soybean condition is 58% good to excellent.
We are looking at a corn crop this year that is late, no doubt about that. But we've had some very good weather since early August. How is the 2008 corn crop doing right now? "This weather is exactly the kind we need," says Roger Elmore, Iowa State University Extension corn agronomist. "The cooler temperatures of a couple weeks ago and then the sunny days have spread out the seed fill period. It's going to add up to some better yields."
You notice that some corn fields are turning brown or golden at the top of the plants and at the bottom, with green in between. Is that normal? "We started seeing that a few years ago," says Elmore. "Certain corn hybrids will do that in certain fields. We call it top dieback. Sometimes it's related to anthracnose, a fungal disease.
Corn heads into homestretch
"We aren't sure if the disease is the primary cause or if it is secondary. You can find anthracnose on the plants. It may just be a symptom of maturation of the corn plant. The corn is translocating nutrients to the seed and it is just one of the phases of maturity. But we really don't know."
What's the corn plant doing now as it heads to maturity? Is it in the process of dying? Is it concentrating all its effort toward the ear? "That's right," says Elmore. "It is concentrating the nutrients that have been stored in the leaves and stalk and moving them into the ear and kernels."
As that happens, the grain increases its weight and is losing its moisture at the same time.
Soybean harvest barely begins
"We are getting close to harvest really beginning in earnest, although a few soybeans were harvested in west central Iowa last week," says Palle Pedersen, ISU Extension soybean agronomist. "We did a few days of combining in our research plots. We have some maturity group zeros and ones we are playing with here in Iowa. We are nearly done harvesting those beans—the plots yielded anywhere from 7 to 60 bushels per acre."
Pedersen has talked to a few farmers around Jefferson and Grand Junction who have been harvesting some beans in fields with lighter soils and they have averaged in the mid-40 bushel per acre range.
Minimize bean harvesting losses
A lot pods are still filling in some fields, and pods on soybean plants this year in general are set very low on the stalks. Seed size of beans in the pods, are smaller than usual this year. "We had to turn down the air on the combine," says Pedersen. "We were running the same setting as last year and we blew the beans out the back of the combine in the plots we began harvesting this past week."
So that's one thing farmers should be concerned about this year, he says. "They need to set their combines accurately. Be sure you don't blow the beans out onto the ground. The beans are small this year. And you have to cut really low to the ground to get those lower than normal pods. With the lack of canopy, particularly if you are planting beans in wide rows, the plants have podded very close to the ground this year. It's going to be difficult to get them all into the combine and not leave beans in the field."
Bean yields lower than expected
Some of the latest planted beans are still green and these fields still haven't dropped their leaves as we head into late September. "There are a lot of green stems on soybean plants this year and particularly the farmers who have combines with straw walkers are going to have a lot of frustration harvesting. The combines will plug up easier with the green stems at harvest," says Pedersen.
Beans are getting close to 13% moisture on the full maturity beans that were planted earliest this year in central Iowa. They are running at 14% to 15% moisture now, if the beans were planted at the optimum time. "I wouldn't be surprised if we see a lot of harvesting begin the weekend of September 27 and 28," he says.
Earlier this summer, Pedersen thought Iowa would see an average soybean yield of 40 bushels per acre in 2008. "I said early-on, just looking at the late planting date for so much of this year's bean crop, I don't see how we can get above 44 bushels. USDA is still forecasting 47 bushels per acre this year for Iowa. I'm three bushels below that and we will see what happens."
"I think there will be a lot of surprises this fall with yield in Iowa," he adds. "I hope they are good surprises. But with weather like we've had the past month or so, with these cool nights, those are not good for soybean yields. It's going to hurt the yield."