I have had dozens of questions about corn on corn management the few weeks.

Interesting commodity pricing, combined with the erratic yields of both corn/corn and corn/beans has generated nearly as much interest in corn on corn as we had last fall. This entry won’t address all the issues, but will give us food for thought for asking questions of local dealers, seed agronomists and at ISU meetings this winter.

A Few of the Big Corn on Corn Issues

In light of the predictions of several climatologists, we may want to consider choosing hybrids with good drought tolerance. Several researchers have shown that late summer drought conditions increase yield losses more in corn on corn compared to corn on beans. Work with your Local Dealer to pick the right hybrids for corn on corn, based on stress emergence, high residue/cool wet soil tolerance, stalk and root strength, leaf and stalk disease resistance, seedling disease resistance to name a few. Most major seed companies have a pretty good scoring system that your Local Dealer can utilize to help select hybrids.

No magic bullet here, corn on corn will require more N. N is high priced this fall, and I’d bet a beverage that it’ll be higher come spring; but don’t skimp on rates. Talk with your Local Dealer and look together at the ISU N Rate Calculator.

As you all remind me, it is imperative to have your P, K and pH levels at optimum for corn on corn as well. Work with your Local Dealer on picking the better fertility fields for corn on corn or bring up the low testing fields before heading into corn on corn.

Rootworms! Several choices here; granular insecticides, liquids, insecticide seed treatments (IST’s) and the new biotech rootworm resistance events. I think we can all agree that for the non-refuge acres, a resistance event is the top choice. I wish I had a better answer for you on refuge acres than granulars or IST’s, but we don’t. In my professional experience, there are some significant differences in performance in the insecticide market. Talk with your Local Dealer and your ISU Field Agronomist for more performance info.

We typically face higher disease pressure in corn on corn. Gray Leaf Spot, Pythium, Diplodia, Anthracnose as well as several other diseases that I can’t spell tend to cause more problems in corn on corn, so work with your Local Dealer to choose hybrids with disease ratings that will give you good protection against at least these diseases.

Planter performance will need to be more closely monitored in corn on corn. The increased levels of trash and “root balls” will make managing planting depth, seed spacing, and seed to soil contact challenging. Uneven distribution of heavy corn residues often leads to variable soil temperature and moisture levels, which can lead to uneven emergence. In looking at seed company and university research, uneven plant spacing and emergence has been shown to combine for yield losses as great as 7-15 bu/acre according to some work. Proper planter care and field by field adjustment can minimize these issues. “Great paper pertaining to this issue.”http://www.agry.purdue.edu/ext/pubs/AGRY-91-01_v5.pdf

I have worked with a wide array of seed firmers, many coulter systems, spade closers, toothed closers, single vs double closers, crowfoot closers, smaller inside diameter gauge wheels, many trash whippers, and a bunch of other stuff I have forgotten about. Most of the time, the grower who had them made them work pretty well under good conditions. A common theme was that not much worked when the soil was wet. It is easy this time of year to say something like “plant only when soil conditions are dry enough to prevent sidewall compaction and/or soil buildup/movement by coulters and gauge wheels.” In reality, there is no easy answer; some growers plant corn on corn fields after corn on beans, so soils have a chance to warm up. Some growers plant non HEL soils to corn on corn and use a tillage program. Some find other unique ways to deal with these issues. Talk to local growers who are successfully raising corn on corn and see if they have some locally useful tips to share.

Weed control; usually more challenging in corn on corn. My recommendation is almost always some type of residual herbicide applied slightly ahead or after planting, followed by scouting and a post emerge application based on what is in the field and what is expected to possibly emerge in the near future. Several Midwest researchers have shown that two pass corn programs consistently give better weed control and higher yields than one pass programs. Yes, my former customers will tell you I am biased against one pass programs, especially in corn on corn, so get another opinion from your Local Dealer.

Soil management- if possible, pick soils with good structure and be careful to avoid compaction. While there are varying opinions on tillage programs and no-till, no matter what your system it is probably important to clear trash from the row area.

Good luck sorting out all the agronomic information above, analyze the government program and crop insurance issues, input costs, output per acre, and match your abilities and fields to the crop rotation that will make you the most money.

SOURCE: ISU’s Clarke McGrath

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