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Late Planting: Tips from Seed Pros

Monday, March 28, 2011
filed under: Hybrid Selection/Planting

There’s still plenty of snowpack across the Northern Plains as of mid-March, and most prognostications are pointing toward the likelihood of a late, wet spring.

Should that come to pass, it will push back seedbed preparation and planting of early season crops, with a resulting domino effect on the planting of many of the region’s sunflower fields.

A late seeding date typically requires some adjustment in hybrid choice and early season crop management. In response to an inquiry from The Sunflower, a list of recommended shorter-season hybrids, as provided by the various seed companies, is provided on page 10.

What management modifications should Northern Plains sunflower producers consider if 2011 does, indeed, experience an abnormally late spring with excessive soil moisture? Here are some recommendations from two longtime sunflower insiders.

Pat Duhigg, Sunflower Breeder, Seeds 2000 —

Shallower planting is one area to consider, since planting deep to moisture wouldn’t be an issue — but quick germination and emergence would be a priority. “Good moisture at planting time will be key in allowing the grower to plant shallower [than usual] to allow the crop to germinate and emerge quickly,” says Pat Duhigg. “And if possible, seed should be treated with a fungicide and insecticide to get the seedling off to a healthy and vigorous start.”

A starter fertilizer or 2x2 treatment also will help plants get off to a faster, more-vigorous early growth, Duhigg notes. “But fertilizer application shouldn’t be overdone, because it will lead to a more ‘rank’ growth and will likely delay entry into the reproductive flowering/seed production phase,” he adds.

Good weed control is very important to “allow the crop to grow faster and more vigorously, without competition from weeds that will rob the soil of nutrients and moisture,” Duhigg continues. He also suggests planting oil-type hybrids at a higher-than-normal plant population (up to 20-25% above normal), given sufficient moisture. A higher population translates into plants with smaller heads. That means faster drydown and, overall, fewer days from planting to harvest maturity. “Use of a desiccant at physiological maturity could also reduce harvest time by as much as 10 days to two weeks under ideal conditions,” Duhigg points out.

One benefit of a late planting can be an escape from head insects like seed weevil, banded sunflower moth and the sunflower midge; also, avoidance of diseases likely downy mildew and perhaps rust.

The above points are geared toward oil-type sunflower. But Duhigg believes they would apply to confection hybrids as well — with the exception of the higher population recommendation. That would not be advisable, since growers who plant confection hybrids “must produce large seed to be acceptable to processors who purchase the commodity,” he points out, “and higher-than-normal plant populations will result in smaller-sized confectionery seed.”

Jay Bjerke, Sunflower/Canola Product Mgr., Croplan Genetics —

Several items should be considered when faced with a late-planting situation, Jay Bjerke notes. Among them are population level, seeding depth, speed of planting, weed control, starter fertilizer, soil moisture, rotation and the specific hybrid(s) one should plant. He offers these observations:

• Slower planter speeds improve seed-to-seed spacing and depth control in both hard and loose soil as you move across the field. If using an air seeder to cover acres faster, remember that smaller “football-shaped” seeds generally work better than longer, more-pointed seeds in air seeders.

• Starter fertilizer helps young root systems develop faster. But don’t apply too high a rate of nitrogen or salt load with the seed. Also, potential for seed injury increases as soil moisture decreases.

• Keeping a decent interval of years between white mold-susceptible crops benefits sunflower. Do not shorten rotations.

• Soil testing is always recommended. Be careful of very high nitrogen levels following corn. If seeding into that situation, plant lower populations and pick a shorter-stature hybrid.

• Sunflower has good herbicide options that were not available a few years ago, such as the ExpressSun® and Clearfield® systems.

• Out-of-control weeds can cause added challenges beyond yield reduction, like extending a crop’s maturity, increasing dockage, causing storage and marketing problems, and contributing to greater weed pressure in future years.

Planting sunflower late under excess soil moisture conditions can bring a different set of challenges compared to planting late with limited soil moisture. Jay Bjerke provides these observations on the two scenarios.

— Excessive Soil Moisture —

• Planting at higher populations tends to reduce plant head size, helping at harvest time with generally drier ’flowers.

• Higher-population fields will canopy faster, aiding with weed suppression.

• Weed control is very important when planting late, and incorporating a preplant herbicide can be challenging with wet, muddy soils. Consider a pre-emergent herbicide like Spartan Advance after planting to increase the odds of consistent weed control.

• The minimum recommended depth of planting is 0.5 to 0.75” of moist soil covering the seed. Don’t go any shallower.

• One of the last — and perhaps the biggest — of items is hybrid selection. While the calendar cannot be ignored, late planting is not a matter of simply picking the shortest-maturity hybrid; it’s more about picking the right hybrid for your field. That includes the disease resistance package as well as yield and oil potential.

— Limited Soil Moisture —

• Planting at lower populations often is necessary under dry conditions to maximize yield and oil.

• The ExpressSun and Clearfield production systems are even more important when a lower population is combined with a late planting. They allow treatment of late weed flushes caused by rain before the canopy is closed.

• Conservation of moisture through wider row spacing and/or no-till can help you capture those oil premiums.

• It’s important to seed into moisture, to a maximum depth of 2.5” and with good seed-to-soil contact. Consider using openers or coulters to push some dry soil aside.

• Hybrid selection in a moisture-stressed environment has similarities to selection for an excess-moisture situation: It’s not just a matter of picking the shortest-maturity hybrid; rather, it’s about picking the right hybrid for that particular field.
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