Needs undivided attention Corn behind wheat demanding

Altheimer, Ark., farmer Felix Smart could barely hide his excitement. He was standing in an 18-acre field of corn nearly 12 feet high. That's good growth for any planting date, but this corn was planted June 6, the day Smart harvested a wheat crop from the field.

Smart, who farms 1,300 acres of corn, 3,000 acres of rice and 1,800 acres of soybeans with his father, Felix Smart Sr., and brother, Jack, believes the program could be a good alternative for soybeans behind wheat, especially with corn yields of 150 bushels or more.

“We have not put a pencil to it, yet. But for our bean yields behind wheat, 50 bushels to 55 bushels is about as good as we can do. And that's pushing them pretty hard. I'm not as sure about that with $9.50 soybeans, but making four insecticide sprays on soybeans like we did this year can eat a whole lot of that price.”

Other advantages to corn behind wheat are reduced costs and simplicity versus early corn. Smart applied about 150 units of nitrogen to his June corn, which thrived in the warm conditions. “When you plant corn in June, it's growing so rapidly that you can use every unit. You plant it and it's up in four days. It doesn't ever quit growing. Everytime I drove by it this summer, it looked like it had grown another 6 inches.”

Smart also liked the low herbicide cost of the practice — one application of 2 quarts of atrazine and 30 ounces of Roundup, put out three days after planting, June 10.

Pioneer agronomist William Johnson, who arrived at the field on a late September morning to tabulate yields for Smart, added that the wheat stubble, the corn's fast growth and the quickly closing canopy of 30-inch rows has a suppressing effect on weeds.

Johnson advises growers not to wait too long to apply atrazine on late-planted corn. In Arkansas, “If you put out 2 quarts of atrazine after June 15, you can only follow with corn. You have to look at that label.”

Corn behind wheat requires five important inputs — water, fungicide, the right genetics, timely management and Bt technology.

Bt corn is essential for corn planted after April 5 (for central Arkansas), according to Johnson.

Smart planted Pioneer 31G71 (HX1, LL, RR2), which contains Herculex for corn borer and the LibertyLink and Roundup Ready traits, at 31,000 plants per acre into wheat stubble behind a combine with a stripper header. Wheat averaged 45 bushels per acre, significantly lower than expectations of around 70 bushels, due to damage from an Easter freeze. HBK Ranger was the wheat variety, planted around Nov. 1.

Johnson noted that the LibertyLink trait (which is a marker for the Herculex gene) can be helpful for corn producers facing replants. In replant situations where a Roundup Ready hybrid was originally planted, “if the grower is still within his 50 percent Bt requirement, he can plant a Herculex hybrid, go over-the-top with Liberty to kill existing weeds and take out any Roundup Ready corn still left in the field.”

A drought-resistant hybrid like 31G71 is essential, too. “It's amazing that seed companies have been able to develop the genetics in the hybrids where they can take the heat. These are some robust hybrids,” Smart said.

According to Johnson, look for drought resistance of between 7 and 8 on a (Pioneer) scale of 9. “With a drought-resistant hybrid, the silks are down in the canopy, and the temperature is a lot lower there. You have three times more pollen falling than you need to fertilize the entire ear. As long as the corn doesn't wilt, you're going to get good pollination.”

Because the environment was so conducive to growth, Smart's June-planted corn had almost 100 percent emergence.

Another important input is an application of water every four to five days. The Smarts water down every middle on their late-planted corn rather than every other middle on early corn. “With the stubble and the varmint holes, I've noticed it's really helped,” Smart said. “And with that wheat stubble there, the soil temperature is still really cool down there.”

Since the hybrid is more likely to be exposed to late-season disease, a fungicide is also a requirement. Smart experimented with several fungicide programs, and left out an unsprayed check. He's almost been afraid to walk into it.

When Smart, Johnson and Pioneer sales assistant Dale Smith harvested sections of the 18-acre field, plots with fungicides yielded 185 to 195 bushels per acre, compared to a little under 150 bushels for the check. All of the programs consisted of two applications of a curative and a preventive fungicide.

Stalks in rows where fungicides were applied were much greener and healthier than where no fungicides were applied. That may or may not always translate into a yield advantage, but Smart pointed out that standability is a good hedge against an extended harvest.

“As the crop gets higher in value, the fungicide becomes more of a customary application,” he said.

Smart believes his fungicide program still needs some fine-tuning, “so we can make one well-timed fungicide application.”

“We have a hybrid coming out next year, 31P42 (HX1, LL, RR2), that has a lot higher rating on rust than this one. It has lower ear placement and just as good or better heat tolerance, and has better standability,” Johnson added. “With that hybrid, I think one application of a fungicide is all you need.”

Smart's overall corn crop was one of the best he's ever had. “We've filled all our contracts and still have 170 acres to cut.”

He would like to expand the corn behind wheat practice next year, and plans to expand wheat plantings to about 600 acres. He'll likely go with 400 acres of corn behind wheat with the remainder in soybeans behind wheat.

That decision is based on pump capacity and the fact that some fields have half-mile rows, “so we have to water every other row. On those fields, we'll go with soybeans.”

Perhaps the most important input was Smart's own timely management of the crop, a commitment he made before any seed ever went into the ground. “I made up my mind early that corn behind wheat would get my undivided attention. Not letting it stress is the key to making it work.”

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