Solid Stand Establishment
Ask any child psychologist about the importance of the first few years of life in forming an individual’s personality. They’ll tell you that initial period is critical. If a child enjoys a healthy beginning (good nutrition, proper medical care, plenty of nurturing), he or she is usually off and running on their way to a productive, satisfying life. But should those first years be filled with deprivation and neglect, life becomes much tougher.
It may be somewhat of a “stretch” to correlate that situation with the life of a sunflower field; but there are some similarities: If the hybrid seeds sown in that field germinate and emerge in an environment conducive to vigorous early growth, the odds of the producer harvesting a bountiful crop at season’s end are much better than if the germination/emergence process is delayed, weakened and uneven. Then the crop plays “catch up” the rest of the season — and also must confront other problems stemming from the deficiencies of those days and weeks following planting.
“Solid stand establishment” means not only placing the appropriate population in a field; it also means having those seeds spaced uniformly within rows — and getting them to emerge at the approximate same time. Sometimes Mother Nature throws monkey wrenches into those objectives; sometimes management mistakes can stymie their accomplishment. Whatever the potential obstacles are, the more they can be avoided, the better the odds of attaining a high-yielding, high-quality sunflower crop.
As any veteran sunflower producer can attest, stand establishment problems are not isolated occurrences. Virtually every grower has, at one time or another, dealt with field spots or entire fields where stands have been erratic.
A four-state 1994 North Dakota State University producer survey found, for example, that emergence/stand was considered by 23 percent of Kansas respondents to be their single worst sunflower production problem that year. Nearly 43 percent of the Kansas respondents said it was among their three worst problems that season. Though the percentages were lower in the Dakotas and Minnesota, a significant number of Northern Plains survey respondents also reported trouble with emergence and stands in their sunflower fields.
While the degree of the problem varies from year to year, conversations with High Plains sunflower personnel suggest a fair amount of consensus regarding the more-common causes of erratic stands. They also provide an assortment of suggestions on steps the region’s producers can take to reduce the likelihood of stand establishment problems in their sunflower fields.
• Field Choice — Though sunflower has the reputation of being able to germinate and grow well under a broad range of soil types and conditions, there obviously are some situations to be avoided if possible. For example, residual carryover from a number of herbicides poses a threat to sunflower, so producers need to be aware of which classes of herbicides are injurious. It’s important to know a field’s herbicide use history and to always check the herbicide labels regarding rotational restrictions.
Disease is certainly another important consideration when deciding which fields will be planted to sunflower. Excessively short rotations or planting sunflower following crops susceptible to similar diseases (e.g., canola and Sclerotinia) need to be avoided.
• Seeding Conditions — With the generally later planting season for sunflower in the High Plains (late May through June), producers often find themselves planting during hot weather and/or having to decide whether to seed into a dry seedbed or wait for precipitation. While the High Plains growing season is obviously longer than in the Northern Plains, Colorado State University area agronomist Ron Meyer believes planting should not be delayed more than several days beyond the target date strictly in the hope of receiving a timely rainfall.
That’s not to say one should plant excessively deep (i.e., three to four inches), however, just to hit moisture. “The better strategy, I think, is to put on a set of trash whippers, whip out some of the dry soil and then place the seed in at two inches or so,” Meyer suggests. Sunflower can emerge from deeper plantings, but emergence likely will be uneven and poorer overall.
A different problem can result from a seedbed’s actually being too wet, as no-till producers sometimes experience. Having the proper press wheels and down-pressure for adequate furrow closure is essential to avoid later cracking and drying out of the seed row.
• Planting Equipment & Calibration — This one is obvious: using a planter or drill that is properly adapted for one’s production system and field conditions. Occasionally, though, a producer moving from a conventional system into minimum- or no-till may not be set up adequately for the demands of his new system. Good seed-to-soil contact is essential in any program, but it requires special attention under minimum- or no-till systems. Appropriate residue penetration or clearance attachments allow that essential seed-soil contact and greatly enhance stand establishment success.
“What’s often a problem is residue lying on the soil — cheatgrass, other weeds or inadequate spreading of straw while combining the wheat,” says Bill Booker, Bushnell, Neb.-based district sales manager for Mycogen Seeds. “If [the residue] is standing, we don’t have trouble; but if it’s lying on the ground, it can plug us up” if not penetrated or cleared.
Minimizing skips or doubles with conventional plate planters involves using the appropriate plates for sunflower, properly sized seed and correct seed knockers. Air drills used for solid-seed or narrow-row operations need to have their metering mechanisms properly calibrated for each sunflower variety (and seed lot) in order to properly distribute the seed.
• Populations — Ron Meyer says plant populations used to be “all over the board” in his area several years ago, resulting in some sizable gaps in eventual plant stands. The wide variance resulted not only from differences in spring soil moisture conditions, but also because many growers were still experimenting with their own management systems in lieu of local research data. That population range has narrowed considerably since then, Meyer says, in light of data from numerous university and industry trials.
In the Burlington area of Colorado, for instance, “we like a final population of around 17,000” on dryland oil-type sunflower, the CSU agronomist explains. In the typically drier district around Akron (some 110 miles northwest of Burlington), a stand of 15,000 is usually more appropriate. Confection stands in the two areas typically run around 15,000 and 13,000, respectively, Meyer says.
• Planting Speed — Ken Berndt, field representative for the Northern Sun processing plant near Goodland, Kan., says some growers have a tendency to drive too fast when seeding sunflower — up to seven or eight miles per hour, in his experience. That excessive speed can result in “seed bounce” and thus inconsistent in-row spacings. Five or six mph should be the maximum speed with most standard row-crop planters, Berndt suggests.
• Insects — Wireworms that have overwintered in wheat residue present a significant threat to many High Plains sunflower fields, Ken Berndt observes. The insect is of particular concern in minimum-till or no-till fields with their substantially greater amounts of residue. The seed treatment “Isotox” provides good protection against wireworm damage to sunflower seedlings.
Cutworms are another potential threat to sunflower stands across broad areas of the Great Plains. Several species are known to damage sunflower at or shortly after emergence. Close monitoring and timely treatment is essential to keep stand losses in check if economic populations of cutworms are present.
• Crusting — Bill Booker says soil crusting is one of the more-common causes of uneven emergence and stand gaps that he encounters. With sunflower’s late-spring planting period, “we generally have hotter, drier weather — and can get thunderstorms” prior to crop emergence, he notes. The fast, hard rains from such storms — when followed by another hot day — can produce thick crusts of baked soil. Even with its reputation for vigor, sunflower can’t pop through a half-inch crust quickly, if at all. The result can be delayed emergence or sizable gaps in rows where seedlings were unable to emerge.
Crusting is less of a problem in minimum- or no-till fields with all their residue and rougher surface, Ron Meyer points out. The typical candidate is the field which has been worked two or three times for seedbed preparation and has a fairly fine texture. A quick run-through with a rotary hoe is the standard response if the crust appears too thick for the emerging crop to overcome on its own.
There are several possible consequences of emergence gaps or unevenly timed emergence:
• Late-emerging weeds can “take over” open spots without the suppressive effect of a nearby sunflower plant canopy.
• Insecticide efficacy is reduced on a field-wide basis if plants emerge and grow at varying rates, since one’s ability to properly time spray operations for peak control is hampered.
• Since sunflower head size compensates in accordance with the proximity of its adjacent plants, heads next to row gaps will become significantly larger. That can result in uneven drydown.
• The bottom line is yield . . . and profit. Despite the larger head size and seeds of compensating plants next to gaps, an inadequate final stand is going to result in lower yields field-wide. In part, those lower yields will be the result of too few plants per acre at harvest; but they’re also reflective of the problems — weed populations, insect damage, etc. — which can be intensified by that lower-than-desired stand. — Don Lilleboe
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