Rediscovering Grain Sorghum

Corn Growers Look at Grain Sorghum in Regions Where Drought is Common

Corn growers are taking another look at grain sorghum in regions where drought is a common problem. (Progressive Farmer photo by Des Keller)

Midway through the final field of grain sorghum harvest last fall, North Carolinian Jason Rhodes dumped a portion of the dark brown BB-sized seed from his combine hopper into a small trailer hitched behind a pickup. A local hunting club was using the sorghum to attract and keep quail on their property.

"Anytime you can sell like that," Rhodes says, "there is added income for me. I wish there were more of that." He and his wife, Shelley, received about $5 per bushel—20 cents more than the thousands of bushels he sold the previous day to the large hog-production company Murphy-Brown LLC. And Rhodes had to haul the grain three hours to make that delivery.

He isn't complaining, though, as $4.80 is fair competition to growing corn in his corner of the world, provided he can get sorghum yields near or above 100 bushels per acre. This was Rhodes first year growing sorghum. He plans to increase production from 100 to 225 acres this year.

SUDDEN GROWTH

During the last several years, grain sorghum has gained traction in parts of the country like North Carolina as an alternative to corn that can better resist weather extremes, particularly drought. U.S. production was about 416 million bushels in 2013, way up from 247 million bushels in 2012. USDA reports the average national yield last year was about 62 bushels per acre.

"Sorghum gives the farmers some herbicide rotational options," says Don Nicholson, a regional agronomist with the North Carolina Department of Agriculture and Consumer Services. "There has been lots of trouble with pigweed/Palmar amaranth in soybeans. You can hammer pigweed with broadleaf controls in grain sorghum."

If pigweeds are controlled in grain sorghum for two or more years, the population of glyphosate-resistant pigweeds is reduced in a following soybean crop. Three years of excellent weed control in sorghum nearly eliminates the resistant-weed population.

MANAGE SCN

"Additionally," Nicholson says, "where we are in eastern North Carolina, there is a lot of lighter soil. Corn doesn't yield consistently well on light land without irrigation." In rotations that are heavy on soybeans, the area has considerable soybean cyst nematodes (SCN). Grain sorghum is a good rotational crop for managing nematodes, he adds.

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Rhodes is growing sorghum near the South Carolina border, southwest of Charlotte. "We typically have a bad weather pattern for corn where we are," he says. "We will get too hot for too many days or weeks with very little rainfall. If corn pollination falls in one of those bad periods, you can produce 80- to 100-bushel corn rather than 160 bushels. I don't see a lot of income in that."

Certainly, growing 200-bushel corn generates more profit than 100-bushel grain sorghum. "But on a regular basis, we can produce 100-bushel sorghum more consistently than corn at 120 bushels or more," Rhodes says. Grain sorghum prices generally track 75 to 80% of corn prices.

The addition of grain sorghum gives Rhodes what he calls a "true rotation." Until now, he would grow soybeans after winter wheat then might let the field lay fallow for a season -- or plant a cover crop to gain nutrients. Last year, he planted grain sorghum following late-harvested winter wheat. Additional weather delays meant he was still harvesting into December.

LESSONS LEARNED

This year, Rhodes planted full-season, not double-cropped, grain sorghum in late April/early May. He's counting on a slight yield increase as a result and a potential premium for the crop if he can harvest by September. In 2012, however, North Carolina State University field trials showed double-cropped grain sorghum outyielding the full-season crop, 89 to 72 bushels per acre.

To move into harvest more quickly, Rhodes will desiccate, or kill, the crop using glyphosate or carfentrazone (Aim) seven to 10 days prior to combining. Last year, Rhodes wanted to save the time and expense of desiccation but won't repeat that mistake. Continued harvest delays due to the weather last fall caused some grain sorghum stands to topple over.

He's also hoping to benefit from a yield bump in soybeans from 4 to 10 bushels per acre. That's generally been the expected increase in soybeans following grain sorghum.

"We need this rotation," Rhodes says, even if they didn't make "a whole lot of money" from sorghum in 2013. "We haven't figured it out yet."

Last year, Rhodes drilled grain sorghum into wheat stubble. Planting was followed with a simultaneous application of a preemergence herbicide to kill existing weeds. Fertilizer was applied prior to planting. "We didn't do split applications even though that's what a lot of the literature recommends," Rhodes says. "Right now, I'm just not set up to do that."

FIGHTING RESISTANCE

Under ideal circumstances, the grain sorghum will thrive ahead of the weeds. Rhodes didn't have to spray for broadleafs during the season but did use a fungicide.

"We want to change the herbicide chemistry to help combat resistant weeds," Rhodes says. "I was starting to see pigweed that was showing some resistance to glyphosate. The way those weeds multiply -- in the hundreds of thousands of seeds -- seeing even one of those plants is really too many."

At present, there are no herbicides that can be used on grain sorghum to kill grasses. In 2010, though, Kansas State University licensed its so-called Inzen technology to DuPont Crop Protection. As a result, Inzen Z sorghum varieties will be tolerant to the company's new ALS grass herbicide Zest. Another version, Inzen A II sorghum, will tolerate Assure II. According to DuPont, those traits are being made available to seed companies.

APHIDS POSE NEW THREAT

Just as grain sorghum acres are increasing in the U.S., an aphid previously believed to feed on only sugarcane may have added sorghum to its diet. The sugarcane aphid first appeared in Florida in the late 1970s. It was 20 years before the pest arrived on farms in southern and coastal Texas and Louisiana in 1999. All the while, the aphids fed on only sugarcane.

Now, in the span of a year, the aphid appears to have begun devastating sorghum fields and was found feeding hundreds of miles north in Oklahoma. Additionally, there is no surefire pesticide to fight the aphid.

"Right now, the only thing I can tell you is that it will move farther north," says Raul Villanueva, an entomologist at the Texas A&M AgriLife Research and Extension Center, in Weslaco. "We're not totally sure if it's a new invasive pest or if it just switched hosts from sugarcane to grain sorghum."

Mild winters have likely helped the aphids spread. And strong winds are probably what carried the aphids north to Oklahoma, Villanueva explains. When high numbers of aphids congregate on the leaves of a plant, the bugs develop wings to use to find additional food.

At the moment, there is no insecticide registered for use on grain sorghum that can handle the aphid, Villanueva says. Transform WG has shown effectiveness. The Texas Department of Agriculture has asked the federal EPA to approve an emergency exemption for its use on grain sorghum to control the aphid in the state. Villanueva and colleagues are also exploring biological controls. However, as the sugarcane aphid populations grow so quickly, he's not sure how effective those materials will be.

(BAS)

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