'Selling Raindrops' in S.E. Colorado
Through it all, sunflower has been a real bright spot on our farm. I’ve grown this crop continuously since 1995. In only one year — 2002, our worst drought year — did it not come through with a respectable yield. (Nothing worked that year, I should add.) Overall, we’ve been able to maintain a 1,400-1,500-lb average through the years — and that includes 2002, when the drought resulted in an average yield of just 200 lbs/ac. Three years ago, we averaged 2,100 lbs across the entire farm; this past season, we came in above 1,700 lbs.
While our annual precip is low, we are fortunate in that our wettest months typically are May through August. Across the period of 1987-2007, our farm averaged 10.88” of moisture during those four months, whereas the remaining eight months had a cumulative average of 6.5”. Together, July and August provided us with about 5.5” of rainfall during that 21-year period. This timing is obviously excellent for sunflower growth and seed development. We plant in mid- to latter June, so the sunflower is just into the bud stage by early August.
All our ’flowers are grown in a no-till system, following wheat. With our limited moisture, controlling weeds is not just a matter of removing competition for the sunflower; it’s also essential for preserving as much soil moisture as possible.
Our weed management program for sunflower begins right after wheat harvest. We’ll usually spray a quart of Roundup in a tank mix with either dicamba or 2,4-D. We also like Salvan®, another effective broadspectrum product. Typically, we’ll need to do a second fall treatment (occasionally even a third, as we don’t believe in letting anything green grow out there prior to the sunflower crop). If the volunteer wheat is heavy the following spring, we’ll go back in during March with a burndown; if not, we’ll wait until late May/early June and do a final preplant treatment shortly before seeding the sunflower.
We use Spartan preplant, often tank mixed with 2,4-D and Prowl H2O. Also, because of the high pH (7.9 to 8.5) of our soils, the maximum rate of Spartan we’ll use is about two ounces. Russian thistle is one of our problem weeds. Neither Spartan nor Roundup handles it well, so if we have a significant infestation we’ll use preplant 2,4-D or Banvel to eliminate the thistle. Yes, that extra application costs money, but we believe it more than pays.
Devil’s claw can be an ugly weed for us. A single plant will grow to more than three feet in diameter, and its woody, hooked claws (seed pods) can be a real pain during harvest. It’s very common to have devil’s claw in our sunflower; so if this weed is out there after crop emergence/early growth, we’ll knock it down with Roundup between the rows, applied by a hooded sprayer.
The best in-season tool for weed management, though, is a full sunflower plant canopy. That starts with adequate soil moisture, a later planting date (mid-June) — and the appropriate plant population. We were down to a 16,000 seed drop for awhile due to problems with the long-horned beetle (Dectes). Our thinking was that the lower population and correspondingly larger stalk diameter would help us manage losses due to the beetle’s girdling. It did; but now we believe we need to get back up around 18,-20,000 for the tighter plant canopy and overall yield.
I usually fertilize for 1,800- to 2,000-lb ’flowers. We stream on most of our nitrogen (in 20” bands) in January, always adding a little sulfur. Because of the cold temperatures at that time, and because we usually receive enough moisture to get it incorporated prior to warm weather, we lose very little to volatilization.
Some folks in our part of the country still have, in my opinion, some misconceptions about sunflower. For example:
• Sunflower ground is bound to blow. — If you are not into a minimum- or no-till program, there may be some validity to that. But under our no-till system, it simply is not an issue. Plus, those standing sunflower stalks really trap a lot of snow (when it does fall).
• Sunflower will ruin your ground for other crops. — Yes, sunflower will draw out soil moisture and nutrients to depths other crops will not. So you need to be prepared to replace them. Farmers looking to keep their inputs as low as possible should not be planting ’flowers. As noted earlier, we fertilize as needed — and we do what we can to preserve as much soil moisture as possible for the next crop.
• Sunflower is a “forgiving” plant, so a uniform, consistent stand is not essential. — Well, maybe it’s not “essential” — but it’s darned important. Not only will consistent seed spacing and plant emergence optimize yield potential and result in a more-uniform field drydown; it’s also a great asset in weed control. Those blank spots within a row are an open invitation to devil’s claw and other broadleaves.
Sunflower is not an easy crop. It’s not for the “faint hearted” or for those producers who gravitate toward the lowest possible input level. But if you are willing to treat it as a priority crop, it will reward you accordingly. I’ll testify to that.
Burl Scherler farms about 14,000 acres (including fallow and CRP) near Sheridan Lake, Colo. Along with sunflower, he produces no-till wheat, corn and grain sorghum (milo). A director of the Colorado Wheat Administrative Committee and the Colorado Sorghum Producers, he also operates Scherler Sales, a seed sales and ag chemical sales/application business.
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