Wind Plays Havoc with Weed Control This Year

Weekly crop survey shows Iowa corn and beans competing with more weeds than usual.

Farmers across Iowa have had a hard time applying herbicides due to wind the past couple weeks. Corn and soybeans now have to compete with a larger than usual population of healthy weeds.

The weekly weather and crop conditions survey, released by Iowa Ag Statistics Service June 11 and based on results as of June 10, shows that the strong winds have caused some sand blasting of corn and beans. Corn root systems are still shallow but corn plants that have been yellow in many fields due to excess moisture are now beginning to green up. "A wide variation is seen in corn stands across Iowa, depending on the date your crop was planted," observes Roger Elmore, Iowa State University extension corn specialist.

Topsoil moisture rates zero percent very short, 7% short, 77% adequate and 16% surplus across Iowa, according to the government's weekly survey.

About 6% of corn, 5% of beans replanted
An estimated 6% of the Iowa corn crop has been or will be replanted this year. Average corn height as of June 10 is 14 inches. Corn condition across the state is 1% very poor, 4% poor, 18% fair, 56% good and 21% excellent. Soybeans are 93% emerged. About 5% of the state's 2007 soybean acreage has been or will have to be replanted. Soybean condition statewide as of June 10 is 3% poor, 19% fair, 60% good and 18% excellent.

First cutting of alfalfa hay, at 49% complete, is 11 days behind last year's 84% and behind the 5-year average of 59%. All hay condition is 2% very poor, 9% poor, 35% fair, 43% good and 11% excellent.

Windy conditions this past week have helped dry out hay and have allowed hay harvesting to continue. First cutting of hay is showing more weeds than usual due to the hard frost earlier this spring that killed out a significant number of the alfalfa plants. The past week's weather has been good for livestock. Pasture condition rates 1% very poor, 3% poor, 22% fair, 57% good and 17% excellent.

Three different corn crops in Iowa this year
Iowa State University Extension crop specialists, in their June 11 telephone conference, report that Iowa has three different corn crops this year. "Corn that was planted early - such as in mid-April through April 25 or so--looks incredibly good right now," says Paul Kassel, ISU area crop specialist in northwest Iowa.

There is some corn planted in early May that is still struggling because it was planted in soils that were too wet. Then there is the "third crop"--the later-planted corn that is coming on pretty strong now in terms of growth and it is really starting to green-up.

"Weeds have been a huge issue for farmers this year, for a number of reasons," says Mike Owen, ISU Extension weed control specialist. "We didn't get a lot of early herbicides applied because of the wet soils. Also, many farmers are using total postemergence programs in 2007 because they have planted corn and beans that have the resistance traits to certain herbicides--like glyphosate."

Windy weather didn't allow timely spraying
Through May and much of June this year, it's been a lot windier than usual, he notes. "We weren't able to spray the herbicides we needed - in many cases. Consequently, we have a lot of fields that now look rather wild and wooly with weeds," says Owen. "I'm afraid a lot of the weeds have already taken their toll this year regarding reducing the yield potential of corn fields."

He adds: "We also have some people in Iowa who didn't use the best judgment this year when spraying their fields. They went out and made some herbicide applications anyway during that windy weather and as a result, we have been getting a lot of complaints about herbicide drift."

Overall, Iowa's crop conditions could be a lot worse, Owen says. "Some farmers are still replanting the wet holes or drowned-out areas of fields. But in general, corn and soybean conditions in Iowa here in mid-June 2007 aren't too bad."

Farmers are sidedressing more nitrogen
Due to the very wet weather this spring from April into June and the higher than usual amount of nitrogen loss that resulted, there is significant need for sidedressing of nitrogen - especially in western Iowa where it's been quite wet this year. "There is a need to apply some sidedress nitrogen for corn in these fields," says ISU soil fertility specialist John Sawyer. "Farmers had better be applying that N pretty quickly, however, if they need it to get it on."

This year's corn crop is really starting to grow fast. "With the conditions we have right now, the Iowa corn crop varies from going into V-9 stage of growth all the way down to some late-planted corn fields that are just emerging. The corn crop in Iowa is quite variable this year," says Sawyer.

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