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Improving the Odds

Tuesday, January 1, 2008
filed under: Planting Systems

Bruce Due suggests putting the issue of evenly spaced sunflower plant stands in perspective: “It’s important. But is it as important as in corn? Absolutely not. With sunflower, you can have a double or a skip, and there are negatives associated with that. Yet it’s not like having a double in corn.”

Fair enough. But having made that point, there’s no doubt Due would still like to minimize uneven plant spacing in sunflower fields — especially when it comes to the number of doubles or triples. “I’ve been in stands where 70% of the [seed] drops are doubles or triples,” says the Breckenridge, Minn.-based Mycogen Seeds agronomist. “Good for the seed company; really bad for the grower!”

Any sunflower producer or seed company representative knows first-hand the benefits of a consistently spaced plant stand:

• More-efficient use of moisture, sunlight and nutrients.

• Improved weed suppression (superior plant canopy).

• Similar pace of plant development (aids in insect management).

• Uniformity of head and seed size.

• More-even plant drydown across the field.

• Better final yield and crop quality.

Sunflower has long been touted for its ability to compensate for inconsistent spacing within the row. Plants adjacent to skips, for instance, will —assuming sufficient moisture and nutrients — produce larger stalks, bigger heads and more seed weight. Though that’s a positive attribute, it’s not, however, what growers strive for — nor should they.

No Need to Overplant

Proper planter equipment, calibration and operation are critical to the final outcome. But achieving the desired plant population starts with the seed bag — and that can be a little tricky in itself. Tim Petry, field production manager for Dahlgren & Company, points out that seed tags commonly understate germination because state regulations require the tag to list the “minimum” germination percentage .

“If the bag says 85% germ, that’s the minimum it can be. The majority [of seed lots] actually run in the low to mid-90s. So some guys tend to overplant,” says Petry, who believes excessive populations are one of the most common mistakes in confection sunflower production. “The perception is that overplanting is how to obtain the optimum yield. Really, it just adds risk. If you don’t have an ideal growing season, if you have dry conditions or disease, you leave yourself at a higher risk. Any benefit you may gain in drydown time doesn’t offset the downside.” The increasing use of Cruiser® seed treatment on sunflower in recent years has further widened the gap between the germination percentage on the tag and what often occurs in the field, Petry adds, since Cruiser’s activity on insects aids emergence levels.

In the Red River Valley area, for growers planting confections in 30” rows, Dahlgren typically recommends a seed drop of around 18,000. “If a guy is in 22” rows and looking at good moisture conditions, though, our target may be a little higher,” Petry indicates. To the west, under more-arid conditions, a seed drop of 16,000 is more standard with confections, he says.

Kevin Wall, sales manager for Breckenridge-based Seeds 2000, says he favors an oil-type sunflower seed drop within the 18,-22,000 range in higher-rainfall areas (or for irrigated fields), with 16,-18,000 more appropriate for drier areas. Wall has customers in the arid western Dakotas who are pulling in 1,000- to 1,200-lb yields — which is profitable for that area — with a 12,- to 13,000 seed drop.

Recommended populations vary considerably in the High Plains, where a significant percentage of the sunflower crop (especially confections) is irrigated.

The High Plains Sunflower Production Handbook suggests oil-type populations under dryland conditions run between 14,000 to 22,000, depending on moisture conditions and one’s yield goal. It also references a Nebraska study in which yields were similar with populations of from 11,000 to 20,000 plants per acre. (But the 11,000 population averaged 300 more seeds per head and a 2.0 lbs/bu lower test weight.)

The university-recommended range for irrigated oil populations in the High Plains runs between 17,000 to 22,000 final plants per acre, while that for irrigated confections typically is from 15,000 to 18,000. For dryland confections, it’s closer to 12,000.

What population justifies replanting? Some situations have an obvious answer, but “I’ll argue with growers in late spring about whether to replant,” muses Bruce Due. “If they’re adamant, you can’t stop them. But we have lots of data to show what sunflower will do for yield at reduced populations. In my estimation, 14,-15,000 plants are just as capable of a [given] yield as 20,000 plants— up to 2,300 or 2,400 pounds.”

Growing What You Sow

Everyone knows “seed drop” and “final plant stand” are two different animals. Not all seeds will germinate, and not all germinated seeds will emerge and grow into healthy plants. Some-times nine out of 10 will; at other times — due to unfavorable soil conditions, planter problems, disease, insects or other factors — the percentage will be considerably less.

Even if a grower achieves his targeted per-acre population, some of those emerged plants are likely to be spaced unevenly within the row. It’s not a perfect world out there, regardless of the crop — and even less so for ’flowers. Sunflower seeds are odd creatures: irregular in shape, much flatter than corn or soybeans, lengthy (especially the new ultra-long confection varieties), and just plain tougher to plant. Toss in the fact that today’s planters were designed for crops like corn — whose seeds are rounder and sown at a much higher population — and it’s little wonder the average sunflower grower deals with skips and doubles.

Again, while a field’s per-acre plant population may be on target, the issue is the distribution of those plants. “The key word is ‘even,’ “ emphasizes Kevin Wall. “If I have an even stand of 15,000 with confections, I’m going to have a pretty good crop with uniform seed size, uniform drydown. It’s the blanks (skips) and doubles that get you in trouble.”

In general, Mycogen’s Bruce Due views doubles or triples as much more of a yield-impacting factor than skips. “They (doubles and triples) are more damaging from a disease standpoint, from a harvest loss standpoint,” he says. “They’re thinner stemmed, so if you’re going to have plants breaking over, they’ll be the ones. And I’ll guarantee you that if one plant in a clump of three gets Sclerotinia, they all will.”

Due sees other effects as well — ones that may not be so apparent to growers. “If you have a lot of doubles and triples and you examine those plants, most likely you’ll find some of the seeds rubbed out of the heads.” When the wind blows, the heads of the “cozy” plants tend to rub against each other. “Over time, that will actually wear seeds right out of the head.”

Seedset can also be affected. During pollination, heads jostling against each other “will rub off anthers, will rub off the female portion of the pistil,” Due notes. “So you end up with heads that don’t set seeds normally.”

Long, consecutive skips down a row obviously are not a good thing — from either a weed control or final yield standpoint. But for Due, the occasional, sporadic skip is not worrisome. “Sure, we’d like to see uniform spacing of every plant out there,” he observes. “But realistically, if I was to count 100 plants and find I have 85 placed ‘normally,’ I can live with that. The nearby plants will try to compensate.”

Optimizing Seed Placement

John Smith, agricultural engineer with the University of Nebraska at Scottsbluff (see article on page 8p) recounts a conversation he recently had with a grower who used a John Deere vacuum planter to seed confection sunflower. “He said, ‘You know, I’m just not happy with my planter.’

“He was using the [flat] plate that Deere recommends for confections. But then I asked him where he had his doubles eliminator set at. And he replied, ‘What’s a doubles eliminator?’“

After discussing that topic, the grower next asked Smith what vacuum setting he was using in his Scottsbluff tests with the Deere vacuum meter for confection ’flowers. Smith indicated he had experimented with a wide range and settled on 12” water vacuum. The grower responded that he had been running at just 1” vacuum.

In Smith’s view, that conversation underscored the core problem inherent in many inconsistent plant stands: inadequate information as to the right equipment and settings for planting sunflower — and confection ’flowers in particular.

“This grower was used to the Deere cell plate-type planter,” Smith points out. For whatever reason, the grower didn’t realize that when using the flat plate, he had to include the doubles-eliminator mechanism. “He installed the [flat] plate, dumped in the seed and started down the field —and of course, he was getting [numerous] doubles,” Smith explains. “So he backed his vacuum way down to where [the monitor told him] he had the right plant population. Well, in the meantime, he was ending up with long skips — and still some doubles.”

Calibrate, Calibrate, Calibrate

“Sunflower is one of the hardest crops to calibrate for,” Bruce Due affirms. “Every hybrid is different. Some of have wide shoulders and narrow points; others have narrow shoulders and are very pointy. Plus, the length of the seed varies so much from hybrid to hybrid.”

Seed company agronomists commonly recommend that growers recalibrate their seeding systems whenever changing not only varieties, but also seed lots within a given variety — especially if there’s a seed weight change. “Every lot number, as long as it has a significant difference in [per-pound] seed count, should be a reason for the grower to check to see if something changes,” Due advises.

“If the [new lot] has only a 200- to 300-count difference and it’s of the same hybrid, it’s not likely to change anything. But if you go to a different seed lot — same hybrid, same seed size — and there’s a 1,200-seed-per-pound difference, I'll guarantee you there’s a change taking place in how your planter is planting that particular seed lot.

“The ‘one size fits all’ approach — for a grower to calibrate his first seed lot and then turn ‘er loose and keep dumping in seed — just doesn’t work," he states.

Due views planter calibration as a huge factor in laying the foundation for a successful sunflower crop.

“I used to work with a grower who used the old IH Cyclo,” he illustrates. “They were a good planter in their day; but if you didn’t have them calibrated right, they could really do a ‘nasty’ on you. He always told me, ‘I can plant anything through my Cyclo.’ And I believed him, because he knew how to calibrate that planter so it would work perfectly. He’d have to play with it for awhile; but when he got done, it was planting right.”

At the other end of the spectrum, “I’ve seen people take a brand new planter out to the field and have nothing but nightmares,” Due states. “If you don’t know what you’re doing, it can be a wreck.”

While none of today’s commercial planters were designed with sunflower in mind, most can, if properly equipped and calibrated, do a good job with this crop, adds the Mycogen agronomist. “I don’t see problems as being a ‘planter-specific’ issue by type,” he says. “It’s a ‘planter-specific’ issue by planter. If a grower has a planter that hasn’t been calibrated right, if it has worn components, or if it has an operator who’d rather be driving the tractor than calibrating the planter, there are going to be issues.

“Every time you go to a different field, your planting conditions change. And if you go to a different field that had a different previous rotation crop, it changes dramatically.”

Due maintains that one of the biggest issues with planting sunflower is the residue from the prior crop. “I get more service calls based on residue management than I do for any other plantability [issue] in the spring,” he states. The issue boils down to seed-to-soil contact and proper seed placement depth. Unless the planter is equipped with the right residue clearance tools, the sunflower stand will suffer.

Given the excellent 2007 wheat and barley crops in central and western North Dakota, for example, Due expects heavy straw in many fields when planting the ’08 sunflower crop. “If we have a lot of straw, we get a lot of hairpinning — especially earlier in the morning when the knives designed to cut through straw just can’t do it very well because the straw is wet with dew. Sometimes it just comes down to looking at that and saying, ‘I need to wait awhile, because I’m not putting seed down into the soil; I’m putting it into the residue.

“[Inadequate] seed-to-soil contact is one of the biggest reasons for reduced stands.”

Dahlgren’s Tim Petry says seeding depth and good seed:soil contact can be particularly important for confections. “Their thicker hull requires more moisture to absorb through for the kernel to germinate,” he points out. “Also, the woodier, thicker hull requires more vigor on the seedling’s part to break through to the soil surface.

“So seeding depth is critical. If you go too deep, it takes too much energy to get out of the ground.” Petry, who recommends a confection seed depth similar to oils (1.5 to 2”), says the bottom line is to “get it into moisture so germination can take place.” In high-residue situations, that calls for the proper residue managers and down pressure — and good furrow closure afterward.

Air Seeders for Sunflower

Numerous sunflower growers — particularly larger-acreage ones in the central and western Dakotas and the High Plains — have used air seeders or drills for a long time. While some have encountered problems, others have been quite satisfied with the results when using their units to seed this crop. Such growers like the more-equidistant spacing of plants in all directions, the quicker plant canopy, the ability to combine in any direction — and, of course, the competitive yields they’ve been able to achieve.

Again, though, calibration is critical. Using the right seed roller for sunflower and then calibrating seed drop before heading out to the field are essential to a satisfactory stand. Most air seeder/ drill manufacturers have developed recommended procedures for calibrating for sunflower — procedures typically outlined in the operator’s manual.

Given that these planting tools were originally developed for higher-volume crops like wheat or barley, sunflower does provide some challenges, however. “One of the biggest challenges with air seeders is getting the population down to where it needs to be,” says Seeds 2000’s Kevin Wall. “When planting a crop like wheat with probably 2.0 million seeds per acre, you can be off a little and still be fine. But with a crop like confection sunflower, where you’re putting down only 15,- or 16,000 seeds, it’s not very forgiving.

“Generally, with air seeders, I have more problems with people over-seeding,” Wall continues. “If there’s one word we have for growers who use them, it’s calibrate. And if they still have any questions, calibrate again.”

Bruce Due says it stands to reason that a planter that singulates seeds “is just going to do a nicer job” when it comes to leaving a consistently spaced sunflower stand. But, he adds, “I’ve seen some solid-seed design planters that work very well. I’ve seen some solid-seeded fields that were beautiful, with no more doubles than you’d have with a row planter. And I’ve seen others that you just shake you head and walk away from — not just triples or quads, but five or six seeds dumped in the same little spot.

“It’s all about knowing your planter, calibrating it and having the right components to get the job done on sunflower.”

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