ISSUE 3    May 19, 2005

SUGARBEET CROP UPDATE

Most sugarbeet fields were planted in Minnesota and North Dakota, except for a few fields that were still wet. Cold conditions that prevailed during the latter part of April slowed germination and emergence and spared sugarbeet fields significant frost damage in the Red River Valley and Minnesota. Unfortunately, growers in the Sidney factory district lost over 15% of their acreage to frost; replanting is near completion. There is now adequate moisture for good growth of the sugarbeet crop as well as weeds!

Mohamed Khan
Extension Sugarbeet Specialist
mkhan@ndsuext.nodak.edu

 

SUNFLOWER PLANTING SUGGESTIONS

Its time to plant sunflower in the next week or two as the best planting dates in North Dakota have been during the May 15 to May 31 planting window of opportunity.

Sunflower plants will compensate for differences in plant population by adjusting seed and head size. As plant population decreases seed and head size will increase. Oilseed hybrids are generally planted at higher populations than confection varieties as the size of harvested seed is less important. Plant populations for conventional oilseed and Nusun oilseed sunflower should be between 18,000 and 25,000 plants per acre with adjustments made for soil type, rainfall potential, and yield goal. Producers who solid seed or plant narrow rows should plant 22,000 to 28,000 seeds per acre. Lower populations are recommended for soils with lower water-holding capacity and if normal rainfall is inconsistent or inadequate. Confection sunflower should be planted for populations between 14,000 and 20,000 plants per acre. Pre-harvest dry down is more rapid in higher plant populations because of the smaller head size. However, higher plant populations may result in increased lodging and stalk breakage.

Proper planting equipment adjustment and operation is one of the most important management tasks in sunflower production. Plateless and air-planters have been used effectively to get good seed distribution. Double seed drops should be avoided and planter adjustments should be made. Conventional plate planters will provide good seed distribution by using correct planter plates, properly sized seed, and proper seed knockers. Commercial seed companies have plate recommendations for all seed sizes. Grain drills and air seeders may be used for seeding though uniform depth of planting and seed spacing may be a problem unless proper adjustments and modifications made.

 

WET CONDITIONS REQUIRE PATIENCE

Rains this past week have caused wet seedbed conditions and increased producer anxiety to get the remaining crops planted. Demonstrating some patience now will be a key if producers want to avoid potential problems later in the growing season. Waiting until the soil has dried sufficiently before working or seeding will result in more favorable conditions maximizing plant stands and final yields. Its always been a sound agronomic practice to maximize plant stands to help in increasing yield potential.

Tillage of wet soils for seedbed preparation can result in excessive clod formation, poor seed soil contact, an uneven and dried-out seedbed, poor mixing and incorporation of chemicals, uneven erratic seedling emergence, and reduced plant stands. Donít be in a big hurry to work wet fields. Patience is the best recommendation when fields are wet. Waiting 1 to 2 additional days usually will not lengthen the growing season, but will greatly aid in obtaining a good seedbed for planting and to maximize plant stands.

When planting in compacted wet conditions the seed is put in an anaerobic environment. When seed germinates in an anaerobic environment, the lack of oxygen generally results in the death of the germ. Seeds that do survive will be weak and the wet soil conditions may be more favorable for the development of soil borne pathogens that otherwise may not be a problem. The end result is reduced stands and lower yields. Also some soils with high clay content tend to harden when drying and cause real problems with seed germination and seedling emergence.

Emergence in compacted conditions will hinder hypocotyl growth, preventing soil penetration by the hypocotyl arch and retards root development. In addition, any crusting that occurs will further prevent the hypocotyls from emerging resulting in seedling loss in soybeans, dry edible bean and sunflower. The end result of both is an erratic and reduced stand. Uneven crop stands typically yield lower than uniform stands due to direct competition of plants at different stages of growth growing next to one another. One positive aspect is that seed placement depths can be much shallower with good moisture.

 

CANOLA ESTABLISHMENT AND STANDS

Canola is emerging, some fields have good stands, some canola has been frosted and injured, with some reported to have erratic stands. The question comes up, what is an adequate stand in canola? Seeding rates of 5 to 6 pounds per acre should result in 450,000 to 650,000 seeds dropped per acre depending on seed size and numbers per pound. An ideal stand of canola seedlings should be 500,000 plants per acre or 11 to 12 plants per square foot. We donít always reach this ideal goal. What is the "minimum" stand of canola population required to still obtain decent potential yield? Research results from Canada and U.S. have shown that 4 plants per square foot is the minimum stand to still expect good yields. Weed competition however becomes minimal with reduced stands. The canola plant has a way of compensating with additional branching and a thicker stem to support the extra branching when growing under a reduced or lower plant population.

An easy method to determine the stand count in canola is using the "hula hoop" method. Use a hula hoop in a drilled or solid seeded canola field. Randomly toss the hula hoop in a drilled or solid seeded canola field. Randomly toss the hula hoop in 10 different areas of the field and make counts within the hoop.

Using the table below, multiply your average counts by the multiplication factor which corresponds to the size of the hoop being used. The product answer equals the plant population per acre. This method will also work with solid seeded soybean in row spacings of 8 inches or less.

Hoop Diameter

Multiplication Factor

30 inches

8,900

32 inches

7,800

34 inches

6,900

36 inches

6,200

38 inches

5,500

Example: 36 canola plants in 32 inch diameter hoop equals: 36 x 7800 = 280,800 plants/A" or 6.5 plants per square foot.

Canola plants per "hoop count" to equal the minimum 4 plants per square foot.

Hoop Diameter

Number of Plants

30 inches

19.6

32 inches

22.3

34 inches

25.2

36 inches

28.1

38 inches

31.7

After you have counted and determined the canola stand, you can investigate further to see if any additional canola seedlings will or can emerge. Dig or scratch below the soil crust and see if any old or new seedlings have a chance to emerge. Once all information is assembled then one can judge to leave a field or replant to another crop. Reseeding to canola is getting late and rather risky for this 2005 season.

Duane R. Berglund
NDSU Extension Agronomist
duane.berglund@ndsu.edu

 

CORN EMERGENCE FROM COLD SOILS

Given the cold weather of the last two weeks, corn planted in early May should start emerging this week in southern North Dakota, but will need at least a week to 10 days of "normal" May weather before emergence will be evident in the more northern counties. When moisture does not limit germination, corn emergence requires about 120-125 corn growing degree days (GDDs) for emergence. Note that these growing degree days are based soil temperature and are likely to lag behind GDDs calculated from air temperatures during this time of the year. Corn GDD accumulations for the first 15 days of May ranged from only 43 at Langdon to 91 at Wyndmere. GDD accumulations can be monitored for many locations in North Dakota by using the "application" option of NDAWN web site:

http://ndawn.ndsu.nodak.edu/cordd-form.html

Prolonged cold soil temperatures after planting not only delay emergence but can also have a detrimental effect on stand establishment and seedling vigor. These problems are exacerbated when seeds are also subject with excessive soil moisture during the germination process. Imbibition of cold water prior to germination can cause cell membranes in the seed to rupture. Cell contents that are released from ruptured cells are an excellent food source for soil pathogens increasing the risk of disease development in these seeds and seedlings. This process has been referred to as imbibitional chilling injury and is most damaging when temperatures are less than 50 degrees. When checking corn emergence this spring, symptoms of cold injury include: stubby and club shaped coleoptiles, leaves emerging from the coleoptile before reaching the surface of the soil, and corkscrew shaped mesocotyl or coleoptiles. Also, seed and seedling rots that are noted may have been induced by chilling injury. For additional information on chilling injury along with photos of symptoms refer to "Cold, Wet Soils: A Recipe for Early Stress" by John Brien:

http://www.agrigold.com/newsletters/files/3.pdf

Joel Ransom
NDSU Extension Agronomist
joel.ransom@ndsu.edu


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