Are yields better than expected?

Corn harvest is well under way in Iowa as I write this, and perhaps completed by the time you read it. Many farmers already report corn and soybean yields are “better than expected.” Does that mean the crop is turning out better than they expected at planting, in early July, in early August?

It depends on the baseline. In early July I heard many talk about being in the “garden spot,” things were looking really good! But then the straight-line winds of July 11 flattened corn across a wide strip of central, eastern and northeast Iowa. Later, hail and windstorms decimated more of our corn in other parts of Iowa.

Then, with such a hot July we were very concerned about poor pollination. The high temperatures certainly sped up crop development to where it was pushing growth stages faster than we would have liked. Of course, it could have been worse.

Some farmers are harvesting badly lodged corn, and they’re getting quite a bit less yield than they would have had if the corn had not gone down. Some fields were flooded out; some were dried out. Yields in 2011 are across the board from “lower than expected” to “higher than expected.” The current state yield forecast (October USDA estimate) is for 169 bushels per acre. If realized, that is 4 bushels above last year but eight below the 30-year trendline.

Tremendous yield variation

Regional differences are obvious this year. For example, the current estimate of 178 bushels per acre as the average for the northwest Iowa district is about 7 bushels below that of 2010, but the 135-bushels-per-acre estimate for southeast Iowa is 37 bushels above that of 2010!

Is there anything farmers should take away from their 2011 corn growing experience? What can farmers learn from this year and do differently next year to try to improve their yield?

There are always things to learn; I’m always on the learning curve. We need to keep thinking, comparing and learning year to year.

This year with the extremely high heat during most of July, I’m not sure we could have avoided a yield reduction, even with good hybrid selection, management practices, etc. In any case, it’s wise to plant a diverse set of hybrids so your crop silks at different times.

By planting a diverse set of hybrids, you can avoid the consequences of a week or several days perhaps of stress occurring during the pollination period.

But when we have three or four weeks of extremely hot weather like we did in July this year, there’s not much you can do to avoid that. Always plant a diversity of corn hybrids in order to spread out the silking dates and maturity dates.

What about Goss’s wilt?

Goss’s wilt, a foliar bacterial disease, hammered some fields pretty hard in 2011; it was fairly hybrid-specific. Pay attention to hybrid selection for next year if you had a problem with this disease this year. Hybrids vary in their resistance to Goss’s wilt. And please remember, since Goss’s wilt is bacterial, foliar fungicides do not control it at all!

Expect more Goss’s wilt in 2012 based on what Alison Robertson, ISU Extension plant pathologist, has observed. The pathogen that causes Goss’s wilt survives in crop residue and is also borne by the air. That means wind can spread it from field to field. If you had this disease in 2011 and you plant a susceptible hybrid in 2012, you are likely to have Goss’s wilt again. It’s an important consideration, especially for continuous corn.

Better than expected — that’s something to be thankful for at Thanksgiving. Let’s try to do what we can, to do much better than expected next year!

Elmore is the Iowa State University Extension corn agronomist.

This article published in the November, 2011 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.