Grain sorghum is more than a “catch crop” for Southwest farmers — but to take full advantage of the crop’s profit potential, producers have to provide more than minimal management.
Advantages, compared to other High Plains crop options, include potentially lower production costs, says Texas AgriLife Extension Agronomist Jourdan Bell at Amarillo, who spoke at the recent Red River Crops Conference at Altus, Okla., a joint venture of Texas AgriLife and Oklahoma State University Extension.
Farmers should consider hybrid selection, planting date, plant population, fertility, pest management (especially for the sugarcane aphid), herbicides, tillage, and moisture management (in dryland and irrigated systems), Bell says.
“Commodity prices are down for all crops, so input costs are a No 1 priority. Sorghum has some lower input costs. Seed costs are lower, as are some herbicide options. Now, you may need to pencil in some insecticides for controlling sugarcane aphids. Also, grain sorghum is more drought tolerant than other High Plains crop choices.”
Grain sorghum is an exceptional companion crop with cotton, she says. Planting cotton into sorghum residue adds carbon to the soil and reduces moisture loss. “Managed effectively, grain sorghum may promote better cotton yields the following year — and there is no reason grain sorghum can’t be profitable as well.”
Grain sorghum requires from 22 to 23 inches of moisture to produce 200 bushels of grain per acre from rainfall, irrigation, or stored moisture.
PEST MANAGEMENT ISSUES
Controlling weeds is a critical aspect of effective management, Bell says. She recommends ample volume — 10 gallons per acre, applied at 20 pounds per square inch of pressure at 5 miles per hour ground speed for the spray rig. “With aerial application, volume will decrease. Coverage is important.”
Farmers often plant grain sorghum behind a failed crop, she says, and may get behind on controlling weed populations. “But you have to manage weeds to make the yield — start clean and stay clean.”
She cautions growers to read product labels to determine which herbicides require a waiting period before planting, and also to identify those that require either rainfall or irrigation for activation.
A relatively new product, Lumax, offers good control of pigweed, kochia, marestail, lambsquarter, and witchgrass, among others, and provides three different modes of action. “Lumax should not be used on sandy soils, and should be used at a lower rate on loamy soils,” she says. “Do not apply to emerged grain sorghum. The label permits application up to 21 days before planting. Applying within 7 days of planting may increase risk of injury.”
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Tests last year at Bushland showed no crop injury, on clay loam soils, applied at 21 days and 14 days before planting. At 2.5 quarts per acre, Lumax would cost about $46 per acre, including application costs, Bell says.
Other herbicide options include Roundup or paraquat for burndown; Atrazine, Milo-Pro, and Sharpen, in addition to Lumax, for soil residual activity.
Pre-emergent herbicides targeting broadleaf weeds and some grasses include metolachlor products Dual II Magnum, Cinch and Parallel; demethanamid, Outlook; alachlor, Micro-Tech; and acetochlor, Warrant.
Warrant is now available in an encapsulated form, Bell says, which provides a little longer soil activity. She cautions that Warrant should be applied before grain sorghum reaches 11 inches in height to prevent injury. It is labeled for either preplant or early postemergence activity, but seed must be safened for preplant use.
Target weeds include johnsongrass, Texas panicum, volunteer wheat, purslane, and pigweed. Cost is estimated at about $19 per acre.
Bell listed several preemergent products with broadleaf weed and grass activity. Atrazine products include Bicep II Magnum and Cinch ATZ. Also available are atrazine plus diemthenamid (Guardsman Max); atrazine plus alachlor (Bullet or Lariat); atrazine plus metolachlor plus mesotrione (Lumax); and safluenacil plus dimethenamid (Verdict). “You must use Concep III treated seed,” Bell cautions.
Dicamba preplant herbicides products Banvel and Clarity may be mixed with glyphosate as a burndown treatment, Bell says, but must be applied 15 days prior to planting.
She reports on a weed control trial at Bushland using Huskie (16 ounces per acre) postemergence for 100 percent control. Treatment included atrazine at 1 pint per acre, AMS, 1 pound per acre, NIS at 0.25 percent, and iron chelate at 13 ounces per acre. Treatment cost was $21.36 per acre, assuming a $5 per acre application cost. She recommends early treatment, 4-inch weeds, for best results.
“If there is kochia pressure, mix Starane NXT (5 ounces per acre) with Huskie.” She says Huskie has a nine-month plant-back restriction for cotton.
ALS herbicide-tolerant grain sorghum may find a place in production systems, Bell says. “This is not a GMO product, but rather a gene identified and introduced into grain sorghum by Kansas State University. It is marketed by Pioneer and Advanta, labeled with Zest herbicide.” Seed could be widely available in 2017, and researchers are looking at yield potential.
“Zest is the only herbicide labeled for use on this seed,” she says. “Johnsongrass is a main target.” She says a test on a farm with a heavy infestation of rhizome johnsongrass showed surprisingly good results. “A second application was needed, and they will see johnsongrass again next year in this field, but the treatment did reduce seed production.”
Herbicide costs cover a wide range, Bell says, and may add significantly to production expenses. “So, does it pay to select generic products over brand names? With commodity prices low, producers may wonder if they should spend more money for the brand name.”
In some cases, it may be justified, she says. “Clarity, for instance, is the generic of Banvel. There are a lot of good generic products on the market. But look at the label — generics may cost less by volume, but do they have the same active ingredients, and are they backed by the manufacturer? Not always.”
Producers may need to apply higher rates of generic herbicides to achieve the same level of control, Bell points out. “The formulation may be different,” she notes; different isomers of an active ingredient work differently. A generic may work. but not as well as the branded product.
She recommends checking labels on generic glyphosate products, “especially the salts, which can affect tank mixes. Also look at stabilizers, emulsifiers, additives, and other inactive ingredients, which may affect handling and mixing properties.
“Herbicide investments may be money well spent,” she says.
Managing sugarcane aphids has also become a crucial production practice, she says. “Sugarcane aphids moved in with full vengeance and have affected High Plains production to a high degree.” Damage includes potential for significant yield loss, as well as harvest and storage problems from the sticky honeydew secretions deposited by large populations.
“We are working in test plots to identify insecticide options,” Bell says. “We’re also working with consultants and producers on scouting techniques.”
Identification is the first step. The sugarcane aphid is similar to the yellow aphid, a pest that’s been around for years. The yellow aphid can be distinguished by two dark cornicles on its back. Sugarcane aphid populations build rapidly, going from 50 per leaf to more than 500 per leaf within two weeks. Bell says timing of infestation is important. “If they come in pre-boot, injury could be 80 percent to 100 percent without treatment.”
Currently, control recommendations rely on Sivanto insecticide. Some harsher insecticides have spiked aphid populations because they wipe out beneficial insect populations early. Transform, which has been available for the past few years on a Section 18 Emergency Use label, is currently being “held up in the courts,” Bell says.
Sivanto application expense ranges from $20 to $25 per acre. “But consider the cost of a complete crop failure,” she says. “We have seen significant yield boost in the High Plains with treatment.”
Researchers are assessing the aphid’s ability to overwinter in the High Plains. Current opinion is that eggs may survive, but not the aphid. If the aphid can overwinter south of Lubbock, Bell says, it can get into the High Plains pretty fast. Johnsongrass is another host for the sugarcane aphid, another reason for effective weed control.
Current High Plains soil moisture levels, and predictions for above average precipitation through spring, could set the stage for an exceptional grain sorghum crop in 2016, Bell says. But farmers have to manage for profitable yields. “Don’t lose yield potential and profit by neglecting weeds and sugarcane aphids,” she says.