This growing season the ISU Extension crops team introduces the Crop Minute, a weekly audio crop update. To start this feature off, Mike Owen, ISU Extension weed scientist, encourages timely application of herbicide during this week's crop minute, telling listeners that moderate to high infestation of weeds can begin to impact crop yield within a couple weeks of emergence.
Look for the weekly Crop Minute on the right side of the ICM News homepage, under More Resources. Owen's report is at mp3 - May 2, 2011.
No-till fields are looking rather weedy, what should you do?
It's amazing how fast corn planting progresses after a few good days of favorable weather with the large corn planters that many farmers have today. Many farmers didn't get started planting their 2011 corn until Monday May 2. That's later than many had finished planting corn last year. As of Monday May 9, some farmers are already done with corn and are starting on soybeans.
"In our area of eastern Iowa I think we will be well over half done with corn planting by May 9 and have a good start on soybeans," says Jim Fawcett, ISU Extension field agronomist based at Iowa City. "Those farmers who planted some corn in mid-April say that the corn in the ground still looks healthy, but it sure isn't growing very fast. Hopefully, we'll get some warmer temperatures soon to help that corn get up and growing."
You may want to reconsider application of 2,4-D as burndown
One problem that is evident in many Iowa areas is that a lot of the planned herbicide applications didn't get made and the no-till fields are looking pretty weedy. If 2,4-D was part of the plan for a burndown, farmers may want to reconsider, since corn and soybeans should not be planted for a week after an application of one pint per acre of 2,4-D LV. Fawcett says he's seen more problems with corn injury from this application than soybeans, but there is also the residue tolerance concern with soybeans.
Some fields are showing a lot of purple flowered weeds, which is a weed called henbit. It's usually more of a lawn weed, but is becoming more common in no-till fields. "It's never a good idea to plant into standing weeds with the idea of coming back later to take care of the weed problem," says Fawcett. "Some weed problems weren't taken care of last year until the corn was over 5 ft. tall, which means that the corn had to eventually grow tall enough to help shade the weeds out somewhat. But the point is, you lose yield when weeds are present in the crop within the first couple weeks after the corn comes up."