Giving Sunflower The Care It Is Due
Wednesday, January 2, 2013
filed under: Optimizing Plant Development/Yields
If you look at maps showing where the Dust Bowl of the 1930s was most severe, the highlighted area covers the Panhandle district of northern Texas and western Oklahoma, along with southwestern Kansas. That region also lies above what has been, in recent decades, one of the biggest drawdown sections of the Ogallala Aquifer.
Joel McClure, whose great-grandfather came to southwestern Kansas in 1908 and spent his first winter living in a covered wagon box, farms near Hugoton in Stevens County. The area’s annual precipitation averages around 18 inches, but it has been considerably less than that the past three years. The situation makes McClure’s center-pivot irrigation systems more critical than ever — and likewise puts even more pressure on him to use every inch of water as efficiently as possible.
Sunflower — specifically, confection sunflower — helps McClure accomplish that objective. He contracts his crop with Red River Commodities based out of Colby, Kan.
McClure is well known in the region’s sunflower circles for his clean fields, excellent yields and high quality. His yield goal ranges between 2,500 to 3,000 lbs/ac on his irrigated confections. Couple that with a very high percentage of large seeds (90%-plus in most years), and it’s apparent why he is enthusiastic about this crop’s performance and potential on his farm.
Of course, not every year produces those kinds of numbers. But McClure follows several key management principles that he believes increase his odds considerably.
• No Tolerance for Weeds — McClure farm team leader Troy Coen puts it this way: “Joel’s threshold on weeds is very, very low. There’s no tolerance.”
While no weed species get a break on the McClure farm, he’s particularly insistent on reining in Palmer amaranth and kochia — to the point of even manually hoeing out some irksome patches of resistant kochia this year. “I have 16 hoes, and this past season there were 16 of us out there hoeing” a total of about 15 acres in one field, he says.
McClure’s first rule for sunflower weed control is to place the crop on fields (typically following wheat or corn) where the weeds have been well managed the previous year. “Then, about two to two and a half weeks prior to my planned sunflower planting date, I’ll put down a tank mix of glyphosate, 2,4-D and possibly one more herbicide option,” he explains. “I don’t want anything left standing.”
Two to three days after that tank mix is applied and the weeds are taking up the chemicals, McClure puts on 3.0 to 4.0 oz of Spartan, depending on the field’s soil type. If a timely rainfall doesn’t arrive, he’ll incorporate the Spartan with the center pivot.
Immediately prior to planting, another application of glyphosate alone will be made, followed by 2.5 to 3.0 oz of Spartan in a tank mix with 1.5 to 2.0 pints of Dual for grass control. In 2012 he also spot-treated with Prowl for some puncturevine patches and achieved very good control.
Does this regimen cause any crop injury to the sunflower? “We have had some on the sandier soils,” McClure says. “So if the sunflower is into good moisture and coming on strong, we won’t water them. Just let them work their way through it.”
• 20-Inch Rows — Planting his confections in 20-inch rows rather than 30s has several benefits, according to McClure — one of which relates to weed control. “You canopy a lot sooner compared to 30s,” he notes, “and that helps suppress any small weeds that may have survived.”
The shade from the tighter plant canopy of the 20s also reduces moisture loss at the soil surface, which was the primary reason McClure went to 20-inch rows in the first place. “So the water we’re applying gets to stay with the plant longer.”
Plant population is another key benefit. “On a 30-inch row, [seed companies] talk about how they’d like to have the plants 14 to 16 inches apart on confections. That’s about 16,500 plants per acre. But we can take that up to 22,000 on 20-inch rows and still have that 14- to 16-inch spacing in the row. That’s a big increase in yield potential for irrigated confections.” The more-equidistant spacing also reduces plant competition, contributing to better plant health and more-efficient use of moisture and nutrients, McClure adds.
The only “downside” to 20-inch rows — if you can call it that — is the challenging of navigating through the tight-canopied field during the bud stage and beyond. “I’ve never crawled through a jungle, but I’d assume this is kind of how it’s like,” McClure quips. “I have crawled down those rows rather than walk.”
• Stand Establishment — To aid good seed-to-soil contact and plant stand establishment, McClure strip tills his sunflower ground in the spring with a DMI unit. “The way our strip-till rig is set up, it probably fractures a 10-inch wide zone; but the band that looks tilled is closer to only four inches,” he says. “I don’t build soil berms, but just use the unit’s berm disks to catch the soil that explodes away from the knife and contain it.”
Planting date in the southern High Plains can be tricky in an exceptionally hot year like 2012. While he and other area growers prefer a later planting date to help avoid the stem weevil, McClure had one field — planted the last week of June — that was not harvested. The reason? Very poor germination and emergence due to extreme soil temperatures. “Right in there was when we had temperatures of 100 degrees-plus for 14 to 18 days,” he explains. McClure’s top fields this year were planted in late May and early June, and he’ll likely trend toward that time period again in 2013.
• Water, Water, Water — “I understand that to grow a good sunflower crop takes water,” McClure says. “Used to be, I thought we could apply nine inches or so of irrigation water and raise a decent crop. But yields are directly related to the amount of water I can apply — up to a point. You can apply 24 inches of water, and you’re not going to gain much more crop than you will with 16 inches.”
That said, McClure is adamant about using whatever water he applies as efficiently as possible. “Every inch of water is more precious than it was a year ago, 10 years ago,” he emphasizes. “We need to make use of every drop of water we pump. It’s a ‘one-time harvest.’ Every inch we pump where we don’t get the best that can be done with that acre inch of water, we’re taking away from our children, our grandchildren.”
To help with his irrigation timing and set length decisions, McClure employs an AquaSpy™ soil moisture sensor system. A five-foot-long probe buried in the field provides real-time moisture and salinity readings at four-inch increments. Those data, updated every few minutes, are available for review and analysis at any time on a secure Internet site.
“Two years ago, my crop consultant told me there was enough water in the profile to turn off the sprinkler,” McClure recounts. “That monitor told me ‘no,’ I needed more. I watered for three more weeks, and my yield went up 800 lbs over what I’d traditionally been doing there.”
• Insect Control & Plant Health — The sunflower head moth and the stem weevil are McClure’s two main insect challenges. The stem weevil insecticide (Asana in 2012) goes on via a ground rig in a tank mix including a grass herbicide (Select). Stem weevil control was excellent this past season, except in parts of one field where he only spot sprayed due to grass weed pressure being very low across most of the field.
He’ll typically spray twice for the head moth, once when about 10% of buds are opening and the second five to seven days later. He also adds a fungicide (usually Headline) to the first treatment for plant health purposes and rust control, should that disease be threatening the crop.
“Maintaining plant health all the way through the season is very important,” he says, “and putting the fungicide on while we’re already applying the insecticide is a lot cheaper than making a separate pass.”
In what was an extremely dry 2012 season, McClure still came through with a very good confection sunflower crop. His lowest field (other than the one planted in extreme heat) yielded 2,550 lbs/ac, while his top yielder produced more than 3,100 lbs. His overall percentage of plump seeds averaged 88%.
In the end, it’s all about giving the crop what it needs — including intensive management, this successful High Plains confection producer emphasizes. “There’s a direct relationship between the amount of effort put into a sunflower crop versus what you get out of it,” Joel McClure states. “If you treat it like a stepchild, it will turn out that way. But if you treat it right, it will do the same for you.”
— Don Lilleboe