Grain sorghum can be a profitable crop if farmers pay attention to some basic production practices, especially variety selection, planting date, seeding rate and weed control, according to a Texas Extension agronomist.
Calvin Trostle offered recommendations on sorghum agronomy, hybrids and weed control at the recent Southwest Crops Production Conference in Lubbock.
If a grower plans to plant early, Trostle recommends he check local average frost date and add two weeks, if soil temperatures are up.
For grain sorghum, ideally, the 10-day average minimum temperature at a four-inch depth is 65 degrees,” Trostle said.
Early planting should depend on the soil moisture profile. With a full profile, growers can plant between April 25 and May 3, with soil temperature at 60 degrees or higher. Adequate soil moisture at planting can carry the crop during flowering.
If a grower chooses to plant later, Trostle said cutoff for medium maturity sorghum, which flowers in 62 to 67 days, is June 30. He said September rains can carry the crop through grain-fill after peak summer heat.
Trostle suggests growers choose a variety that has been researched over multiple growing seasons.
“Demand drought tolerance and greenbug resistance,” he said. “A common mistake is planting the cheapest seed you can find. Be willing to spend an extra 50 cents to $1 per acre for a proven hybrid.”
Trostle's research shows NC+ Y363 and 371, DeKalb 41Y, 40Y and 44, Sorghum Partners KS 585 and KS 524 as good choices for dryland production.
Seeding rate depends on available soil moisture, Trostle said. “For early July plantings with low available moisture, reduce target plant population to about 18,000 to 20,000 seeds an acre and plant a medium-early to early, drought tolerant hybrid.”
Under a wide range of conditions, Trostle suggests a common seeding rate of 30,000 to 35,000 seeds an acre, which should produce 20,000 to 25,000 plants per acre. He said seeding to obtain a modest plant population is agronomically and economically less risky than seeding for a higher plant population under droughty conditions.
Trostle's research shows Monsanto DK55 and DK 54, Asgrow A581, A571, A570, Missile; Crosbyton Seed 1489; and Pioneer 84G62 are good choices for irrigated sorghum.
“As with any planting situation, first and foremost check soil moisture. If irrigation is limited but the soil moisture profile is good, plant 50,000 to 55,000 seeds per acre, but if the soil moisture is not adequate, 40,000 to 45,000 seeds an acre may be more appropriate.
“Where irrigation water is adequate, farmers may plant up to 80,000 seeds an acre.
Trostle said new herbicide choices for sorghum are limited.
He warned growers to be careful with 2,4-D or any herbicide containing it.
“Many farmers each year injure their crop. Yields are sometimes hurt, even though the plant did not appear injured. Sprayer equipment, applicators, even labels aren't perfect.”
Atrazine is a good choice, best if applied by emergence.
Trostle also presented Brent Bean and Matt Rowland's Amarillo research on carfentrazone-ethyl (Aim), a contact herbicide with little or no residual activity. Trostle encourages tank mixes.
The research shows that Aim, when used alone, does not provide satisfactory control of palmer amaranth; however, control improved when Aim was tank-mixed with atrazine or Clarity. The research also shows that Aim gave excellent control of velvetleaf.