Big Yields and Tiny Aphids in Crosshairs

April 6, 2016 01:00 PM

Ear to the ground, Kent Winter knew an army of millions was set to roll across his Kansas farm.

In late July 2015, the invasion began. A wave of white sugarcane aphids settled across his grain sorghum, threatening to destroy yield and turn the fields into a sticky, honeydew mess capable of clogging combines. He steadied his crop nerve, placed chemical crosshairs on the aphids, and waited for a clear shot. When Winter, 60, squeezed the trigger, he didn’t know he was protecting bin-busting grain: the best sorghum crop of his life.

Strategies for Sorghum Success

Similar to many areas across the Midwest during the 2015 planting season, Winter’s Sedgwick County farmland was pounded by extreme rains at the end of May and into early June. Typically, he begins planting grain sorghum June 10, but the heavy moisture pushed planting to June 20. Unlike soybeans, grain sorghum isn’t daylight-sensitive, and with plenty of Kansas heat units bearing down in mid-summer, the late planting wasn’t a negative issue. With his soil's moisture profile filled to the brim, Winter bumped his planting population to 45,000 seeds per acre on 30” rows, protected by a Concep lll treatment.

Winter goes with a single sorghum variety across full-season, dryland acreage, and planted Pioneer 85G03 in 2015. He also planted limited double-crop acres with Pioneer 86G32--no-till sorghum behind wheat in standing stubble.

Winter treats grain sorghum as a first-rate provider, no different from any other crop. “We try to manage sorghum just as aggressively and effectively as other crops,” he notes. On fertility, Winter adheres to 1.2 lbs. of nitrogen required per bushel of expected yield and adjusts the application rate according to carryover nitrogen found in soil tests. Usually, he puts on anhydrous ammonia with a chisel in mid-spring, but the rains forced a change and he chose to spread urea the week before planting.

Timing of nitrogen is a huge key to grain sorghum success, says agronomist Michael Speer, Farmers Coop Elevator Co., Mt. Hope, Kan. “Two weeks before Kent’s grain sorghum headed out, we hit it with another 35 to 40 lbs. of nitrogen. When he plants, he’ll put down 6 or 7 gallons of 28% liquid UAN,” Speer describes. “On double-crop grain sorghum, he’ll also come back later and top-dress with urea.”

Grain sorghum roots reach deep into Winter’s past as a fifth-generation farmer. In 1957, his father began planting grain sorghum in rotation with wheat. Stretched across 1,500 nearly level to gently rolling acres, Winter’s operation lies 20 miles northwest of Wichita. His acreage is mainly dryland, and the majority of Winter’s ground is silty loam in a minimum tillage set-up. Half the land is in wheat and half is split between alfalfa, corn, grain sorghum, and soybeans.

Grain sorghum is Winter’s “ace in the hole” for enduring the hot and dry conditions common in Kansas during mid and late summer. It is more forgiving than corn and soybeans at critical stages and will wait longer for moisture, Winter says. He relies on the added diversity of grain sorghum in his mix of summer crops because it spreads risk and workload, especially at harvest time. “It also brings another seat to the rotation table, which enhances overall yields of all my crops due to the change-up, along with interrupting weed, insect and disease cycles,” he adds.

'I Don't Think We're in Kansas Anymore'

As the growing season headed into July, Winter kept seeing favorable skies carrying buckets of rain. Most years, Sedgwick County is battered by a hot and dry punch combo, but timely moisture was available much of the summer. Winter knew the rain could translate to substantial yield gains. “I looked out my window at the surrounding countryside several times and said to my wife, ‘I don’t think we’re in Kansas anymore.’”

Yet, there is no crop management without wrinkles. Sugarcane aphid jumped into Louisiana grain sorghum in 2013 and spread to surrounding states at a quick march. Winter had been given ample warning by Kansas State University (KSU) Extension personnel to be on the lookout for sugarcane aphid blowing in from the south.

Zach Simon, KSU Extension, watched the map light up south of Sedgwick County as the aphid advanced into Kansas. Simon used email, websites, Facebook, Twitter, and word-of-mouth through co-ops and seed dealers to advertise an early August meeting with only a 20-hour window of notice for growers. “We tried not to cause panic, but still wanted to emphasize the severity of the situation,” he explains. “We told growers to scout, figure the percentage of a field’s infestation, and then treat.”

When the aphids reached Winter’s farm, 100-degree Fahrenheit temperatures enhanced the insects' rate of reproduction. Sticky, shiny residue was beginning to form in fields as Winter held back until colonies were at 20% infestation rate, and then he unleashed a ground-rig sprayer at the beginning of August. He hit the aphids with 4 ounces of Sivanto and 20 gallons of water per acre to ensure adequate coverage. Timing was spot-on and the single application carried the day. “Kent did well,” Simon recalls. “Other growers got smoked. Due to aphid damage, there were a few fields that weren’t harvested, period.”

“We jumped on sugarcane aphids earlier than others and it worked,” Speer says. “I don’t know about next year. Experts tell us we needed a hard winter to keep them south, but we’ve had mild weather. Everyone is certainly a little nervous the infestation may be worse in 2016.”

Winning the Aphid Battle

And when the smoke cleared after the aphid battle? Winter’s November fields were waiting with the best sorghum yields of his career. Even after moisture shrink, he hit dryland milo yields of 150 bu. per acre, compared with his typical yields in the 90 to 105 bu. per acre range. His double-crop sorghum also was outstanding, tallying 127 bu. per acre. “I attribute the big yields to God’s blessing with timely, beneficial rains during the growing season,” Winter explains.

Based on a lifetime experience with grain sorghum, he stresses fertility as the premier agronomic factor for strong yields. “Never cheat on fertility. You’ve got to have adequate nitrogen to get strong bushels. It doesn’t matter which form, but it must be timely.”

On the heels of fertility, Winter emphasizes weed control. A clean first month of growth is vital, until the canopy and shade take over to carry the crop. Anything less and weeds will dog the sorghum until harvest. Glyphostate-resistant Palmer amaranth is a constant worry for Winter and is a significant driver of crop rotation. In 2015, he sprayed Lumax pre-emergence on his full-season sorghum and gained excellent control.

Resistant pigweed troubles began on some of Winter’s fields in 2013 and the problem has exploded. “With milo, get the pigweeds early or you’re in trouble, as there are very limited options to come back over the top of milo to control weeds,” Speer warns. “Resistance to Roundup has gone crazy. In 2015, we got barely any management out of Roundup at all.”

As for marketing opportunities, Winter has a modest amount of grain bin storage to catch markets in the offseason, but says the best chances come when bushels aren’t in hand. “When a window opens, we have to be ready to make a bushel commitment and lock in the income. Every grower has his own expenses and his own ideas about where the break-even line rests.”

As the 2016 season rolls in, a humble Winter will be watching for sugarcane aphid and hoping to catch a few more timely rains on Kansas farmland originally purchased by his grandfather. "I'm just blessed to be in a good area with fine neighbors. There are many excellent sorghum growers nearby, and we learn from each other. New challenges come with every growing season and we have to step up and give it our best shot."

What have you used to fight aphids in your fields? Let us know in the comments.

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