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ISSUE 6  June 11, 1998



    The North Dakota Soybean Growers Association are again sponsoring a yield contest in 1998. Directors of the Soybean Growers Association decided to sponsor and conduct the yield contest once again. Most rules of the contest are similar as in the past. Divisions and geographic boundaries will be the same as last year. The state has been divided into four growing regions, plus a separate youth division, irrigation division and a no-till division. Both adults and youth can enter and compete in the contest. Youth must be members of 4-H or FFA.

    August 31st is the entry deadline. A fee of $20 per adult entry and $10 per youth entry will need to accompany all applications. Inquiries or entry forms can be obtained from:

North Dakota Soybean Growers
Association Office
415 38th St SW - Suite C
Fargo, ND 58103
Telephone (701) 281-1725



    Flax is an alternative oilseed crop that can be late planted with reduced yield potential. How late is the question many ask. Below are data from studies at the NDSU North Central Research and Extension Center at Minot, ND.

    Flax seeded the middle of June, late June and early July, periods 3, 5 and 6 yielded 32, 52 and 84 percent less than flax seeded in early May (see table below).

Flax seeding date studies, Minot

Seeding periods

Yields (bu/A)

1st (Early May)

2nd (Mid-May)

3rd (Late May)

4th (Early June)

5th (Mid-June)

6th (early July)







Nine years (1977-85) yields averaged over 10 varieties

    Mid June planting of "early" varieties yielded 79 percent of their early May planting while late maturing varieties planted in mid June yielded 42 percent of their early May planting. NorLin was the highest yielding early variety when seeded the middle of June - period 4. These data support the recommendation to plant early maturing varieties. When seeding in June early maturing flax varieties suggested include: NorLin, Flor, Culbert 79, Clark, Linton, Verne, Prompt and Day.

    In summary, this nine-year study of planting date of flax indicates that delayed flax planting will reduce yield potential. Flax planted in periods 2 through 6 yielded 93, 79, 68, 48 and 16 percent, respectively, of flax planted in period 1 when averaged over all varieties.

Duane R. Berglund
NDSU Extension Agronomist



    Using a hula hoop provides as accurate method of evaluating stands in drilled or narrow row soybeans. Randomly throw the hoop into the field and count the number of soybean plants inside the hoop. Using the table below, multiply your count by the multiplication factor which corresponds to the size of the hoop being used. Product equals plant population. Do this a minimum of five times per field.

Hoop Diameter

Multiplication Factor

30 inches

32 inches

34 inches

36 inches

38 inches






Source: Walking Your Fields Newsletter
Pioneer Hi-Bred Inter. Inc.



    Yield reductions due to hail damage on small grains depend on the growth stage of the crop, stem injury, and the extent of defoliation.

    Small grains in the three to five leaf stage can withstand complete defoliation from hail and recover. During this stage the growing point is below the soil surface and will not be damaged. Once the growing point extends above the soil surface it is vulnerable.

    Damage to the growing point shortly following jointing will result in loss of production from that tiller. If the damage occurs prior to the flag leaf stage the plant may initiate new tillers and maintain a reduced level of productivity.

    Once jointing has begun the plant has lost its ability to initiate new leaves on that tiller. Defoliation following jointing will dramatically reduce yield even if the growing point has not been damaged.

    Hail damage to small grains causes the greatest damage from the boot through later stages. Yield reductions result from both injury to the stem and defoliation.

    The effect of stem bending on yield depends on the location of the bend and the stage of the crop. Stem bending immediately below the head results in the greatest yield reduction.

    Research in North Dakota indicates that stem breakage at heading in small grains results in the greatest yield loss and ranges from .33 percent in barley to .61 percent in wheat for each percentage of stems bent; ie. if 33% of the stems of a wheat crop are bent you could expect a .61 X 33 = 20% yield reduction. Reductions in yield from bent stems are progressively less as the crop matures until the crop becomes susceptible to shattering.

    Estimating yield reductions is difficult if a hail storm results in leaf damage without visible stem damage. Although all leaves can be damaged during a hail storm the flag leaf generally exhibits the greatest damage. The flag leaf accounts for 80 to 90% of carbohydrate assimilate needed for grain fill; but when removed the remaining, leaves if, healthy may compensate for its loss. Limited research indicates that yield reductions due to loss of the flag leaf is at least equal to that of bent stems. The loss of all flag leaves at flowering may only result in a 10 to 20% yield reduction if lower leaves are actively photosynthesizing. If other plant parts are diseased or otherwise damaged the yield reduction will be much greater.

    When determining total damage from hail both bent stems and leaf damage must be taken into account. Relatively high levels of stem breakage can occur and acceptable yields obtained if the plant has sufficient undamaged leaf area. Total defoliation immediately following heading in small grains will generally result in a crop failure. Yield loss due to hail at the hard dough stage and later is wholly a function of shattering and lodging.

Michael Peel
Extension Small Grains Agronomist



    June is an important month to keep abreast of horticultural duties. Mess up now, and the "regrets" will show up next growing season! Here is a "laundry list" of reminders for the horticulturally dedicated:

    Prune lilacs, viburnums, mock oranges, and other spring flowering shrubs if needed. Don’t delay, since these shrubs will be setting next year’s flower buds during the summer months. Pruning in late summer (after Labor Day) will remove the wood with flower buds, which will reduce or eliminate flowering next spring.

    Some apple trees are dropping fruit. This common phenomenon known as "June Drop," occurs when the fruit are spaced about 6 inches apart. This will allow for the remaining apples to develop to their full potential, and remove unnecessary weight. This could save the tree from extensive damage should there be an August windstorm!

    Our tender warm-season vegetables have had a hard time of it during the recent cold snap. Most will be set back a little, whether or not they received any direct frost. Tomatoes, peppers, eggplant, cucumbers, beans, etc. may show some damage as a result of the low temperatures in the form of discolored foliage, slow growth, or blossom drop, depending on how far along they were. Most will recover to produce a bountiful (but later) crop.

    When watering newly planted vegetables and annual flowers, try to do so in the early morning hours, and avoid getting the foliage wet. This will go a long way in reducing the incidence of disease. Tomatoes, peppers, and geraniums seem to be especially disease prone from overhead watering. To cut down on watering frequency, apply organic mulch (peat moss, compost, or bark) around the plants after the next watering.

    Keep the lawn mower blades sharp and the mowing height at 3 inches. Roots develop in proportion to top growth in grass plants; taller grass means deeper roots, and deeper roots mean better tolerance to heat and drought.

    Finally, take my word for it - weeds pull easier from moistened rather than dry soil! Go out a day or two after a rain or a good watering and get them out before they set seed! Canada thistles are especially bad, since they produce 680 viable seed per stem! Allowing one to flower and go to seed could spell disaster in a nicely set garden.

Ron Smith
NDSU Extension Horticulturist
and Turfgrass Specialist


Yellowheaded Spruce Sawflies

    I have received numerous questions about yellowheaded spruce sawflies this spring. All native and introduced species of spruce grown in North Dakota are potential hosts to yellowheaded spruce sawflies. These insects are often discovered as late-instar larvae feeding on older needles, at which time much of the damage has been done and chemical control becomes difficult.

    Larvae have yellowish- to reddish-brown heads and olive-green bodies with six gray-green stripes running the length of the body. They will rear up in a characteristic "s" when disturbed. Larvae will reach a length of about 18 mm before they drop to the ground in July and spin a cocoon where they will overwinter as prepupae. In early spring, tan to straw-yellow adults emerge, mate, and lay eggs in current year’s needles at approximately the same time as the young shoots lose their bud caps. The eggs hatch 4 to 12 days after they are deposited in the needles; therefore, we should be monitoring now for the insect in areas where it has been a problem in the past. Young larvae will begin feeding on new needles and will move to older needles as they mature. Open grown trees that are 5 to 9 years old (3 to 18 feet in height) are more vulnerable to yellowheaded spruce sawfly damage than are older trees or trees in dense stands.

    Healthy trees will often survive 100% defoliation from the yellowheaded spruce sawfly, but three or four consecutive years of defoliation can kill a tree. Spruce trees killed by repeated attacks of the sawfly are more common in northern North Dakota than in southern areas of the state. The first year of defoliation should be taken as a forewarning to monitor and treat, when necessary, for the insect in subsequent years.

    Although rodents will feed on the prepupae and birds on sawfly larvae and adults, these predators, in addition to various parasites, are not always effective in keeping yellowheaded spruce sawfly populations at acceptable levels. If infestations are light, adequate control may be achieved by simply removing young larvae by hand. When an isolated ornamental tree is infested, spraying young larvae off of the tree with a strong jet of water will often be effective in reducing insect numbers. Yellowheaded spruce sawflies tend to attack the same trees repeatedly; therefore chemical control often becomes necessary as sawfly populations increase. For chemicals used to control sawflies see the table on the last page of Extension Circular E-296 "Common Insect Pests of Trees and Shrubs in North Dakota."

Freeze injury

    An assessment of trees in areas where freezing temperatures occurred is not complete, but preliminary observations showed that most trees handled the temperatures quite well. Many trees developed a reddening in leaf color and oak and green ash in the Turtle Mountains showed some marginal necrosis of leaves. Healthy trees that lost their leaves from the freezing temperatures will likely recover with a second flush of growth. Whenever practical, any dieback that may result from the freeze should be pruned out after the second flush of growth is complete.

Marcus Jackson
Extension Forester

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