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Preliminary Results: Spring Spacing Survey

Thursday, August 22, 2013
filed under: Hybrid Selection/Planting

Just as an archeologist sifts through the soil, searching for artifacts, agronomist Max Dietrich sifts through the soil, searching for sunflower seeds, insects and any other clues to why some plants didn’t grow.

It’s part of the annual survey the National Sunflower Association has done for the past 12 years (with the exception of 2004) in sunflower fields in Minnesota, North Dakota, South Dakota, Kansas, Colorado, Nebraska, Texas and Manitoba. Until now, the survey has only been done in the fall to provide data for growers to make better management decisions. But this year, surveyors are checking fields in Minnesota, North Dakota, and South Dakota twice—once in the fall and once now, in the middle of growing season. This year, they’re looking for something more. In this first-ever early survey, they’re looking at plant spacing and trying to determine why spacing is often off.

“Every year it comes up that skips are a problem, but we’ve never been able to tell why there are skips, because the plants are in the final stages of development when we do our fall survey. This survey is being done for the first time ever to find out the reasons for the skips,” says John Sandbakken, NSA executive director.

There are lots of reasons for skips, including poor seeding conditions, failure to adjust the planter, driving too fast, poor germination, disease, or insect damage. The idea behind this survey is to pinpoint what’s causing skips in fields this year, and then to find a solution.

Here’s how this new survey works: Agronomists like Dietrich, who is with

Pioneer, are looking at oil sunflower fields and confection fields in North Dakota, South Dakota and Minnesota. The fields belong to different growers who seeded with a planter. Before they get to the fields, surveyors contact the growers for details like planting date, hybrid, seeding rate, previous crop, tillage practices, as well as fertilizer and herbicide application timing and rates.

Once in the fields, surveyors mark their entry point with a flag so the same area can be surveyed in the fall. They do two evaluations in each field: one 100 feet into the field, and the second about 50 feet further in. They examine two 25-foot rows and record the total number of plants in each row, keeping a close eye out for doubles (plants four inches or closer) and skips (18 inches or more between plants). Skips are then evaluated or diseases, insects, birds, or rodent activity. Then, they dig. And that’s when they find the most clues. So far, most of the clues Dietrich has found lead to insects as the major culprits.

“We’re seeing some seeds lost to wireworm. They are eating the seed before it can become a plant,” says Dietrich. Wireworms feed on the developing roots of a seedling or a germinating seed. The seedling often dies before emergence or wilts shortly after emergence. Wireworms can cause heavy damage and require fields to be replanted. The seeds used in the field Dietrich surveyed were treated with Cruiser® insecticide, which provides systemic early-season protection in both germinating seed and young plants from damage caused by wireworms. He says losses would be much higher if seeds were not treated with Cruiser.

There’s another common factor in the fields Dietrich has surveyed: seeding depth. “This is a concern because plants that are too shallow have fewer leaves and weaker root systems. That means the plants aren’t as strong as they should be,” he says. Sunflower should generally be planted at a depth of an inch and a half to two and a half inches deep. Germination generally requires a soil temperature of 50 degrees or more at seed depth. Many of the smaller plants Dietrich has found in the survey were planted shallower than the larger plants.

Dietrich’s findings are consistent with those found in other survey areas. As of this writing 18 fields have been surveyed after sunflower establishment, in 12 counties. (two in Minnesota, one in South Dakota and 15 in North Dakota). The majority had oilseed sunflower (17 fields), while only one confection sunflower field was evaluated. Hans Kandel, extension agronomist with North Dakota State University, is compiling the data. He says insect damage appears to be affecting 1.5 plants per 100. “The insect damage occurred both at germination and early stand development,” says Kandel. “In 5.5% of the fields cutworms were found and in 39% of the fields wireworm were present. One field was reported to have springtails.”

As for seeding depth, Kandel says from the data he’s complied so far, the average seeding depth was 1.75 inches and the plants had, on average, 13 leaves.

Although the data are still preliminary, and there is much more research to be done, Kandel points out some other interesting findings. For example, farmers who applied starter fertilizer have significantly more plants per acre: 19,654 plants per acre compared to 17,743 for producers who did not apply fertilizer during seeding. “This needs to be investigated in more detail,” says Kandel. “It is a significant difference, and we need to study it more. However the difference could also relate to higher managerial skills of the producers who apply starter fertilizer.”

That’s not the only significant difference. Kandel says data show that producers using wheat, barley or oats, or corn as previous crop had 19,705, 19,297 and 17,623 plants stand per acre. “That’s not a significant difference,” he explains. “However, if we compare all small grain crops (sunflower after wheat, barley or oats) the stand was 19,557 compared with the 17,623 stand for farms growing sunflower after corn (7 out of 18 fields). This is significantly different. There tends to be more plant residue in corn fields. This finding needs to be looked at in more detail.”

Still, Dietrich likes what he’s seen in the fields so far. “The fields I’ve been in have above average to excellent yield potential,” he says.

The same sunflower fields that were surveyed this summer will be included in the fall survey so that the spring and fall observations can be compared. Results in this first year will determine whether the spring survey will be conducted again.

— Jody Kerzman

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