ISSUE 4  MAY 27, 1999

VIRTUAL SUMMER AND HORTICULTURAL PRACTICES

    With Memorial Day weekend, we often think of this as the arrival of summer, even though our calendar
tells us we have another 21 days to go. The winters are long in our area and the growing season short, so we
don’t want to slip up on taking care of our horticultural plantings at the right time.

Lawns and Lawn Mowing:

    Do it as needed, not when it is convenient. We are blessed with extremely long daylight hours at this time
of year, and can take advantage of getting such mundane chores out of the way during late afternoon or
early evening hours.

    Few people place adequate importance on this often boring, tiresome chore. The blade should be sharpened
at least once during the season, and the grass kept at a height of 3" to minimize stress. At this height, there will
be a more extensive root system that will be better able to mine water and nutrients from greater soil depths.
Allow the clippings to fall each time (unless windrows are formed from delayed mowing), and alternate the
direction of mowing each time whenever possible. This will keep the turf nicely dense, making it better able to
resist the summer stresses of wear, higher temperatures, weed seed being blown or tracked in, and assaults
from insect and diseases.

    The biggest "criminal offense" I often find in lawn care is in the watering. If the homeowner has an automatic
irrigation system, they tend to overuse it to the detriment of the turfgrass. Except under the most severe conditions
or soil with a high sand content, turfgrass should not be irrigated more than 2 times per week. Water in the early
part of the day and make sure the root zone is wetted completely during each irrigation cycle.

    It happens every year at this time - seed heads forming on the lawn grass. This is simply the normal transition
from the vegetative to the reproductive stage of growth. It is controlled mostly by day length and low temperature
exposure. Low nitrogen availability will also contribute to increased seed head formation. Certain species and
cultivars of bluegrass are noted for their ability to initiate flowering in spite of good fertilization practices. It is often
asked if the mowing of the lawn should be delayed to allow the seeds to mature and fall to the soil to help thicken
the lawn. The answer is "no." The lawn will not thicken up from this, and the gap in mowing frequency will only
lower shoot density, giving weeds an opportunity to get established. Fight the temptation to lower the mowing
height to get all the flowers. They will simply re-initiate below the previous cut. In 30 days or less, the seed
head unsightliness will be forgotten!

    Most quality nurseries and garden centers in our area carry containerized and B&B stock through the summer.
If you have been caught up in the hustle of the spring and failed to get some woody plants installed, don’t think it
is necessary to wait until late summer or next spring. As long as post planting care can be provided (adequate
water, mulching, etc.) those plants may as well be establishing themselves in your property than to sit in the
local nursery.

    A suggestion I would like to make for those who are considering adding or replacing some shrubs in the
landscape this year is to consider some viburnums. American cranberry bush (Viburnum trilobum), Arrowwood
(Viburnum dentatum), Blackhaw (Viburnum prunifolium), and Nannyberry (Viburnum lentago), all
have positive landscape values to add - attractive white flowers, fall color, edible fruit for birds, attractive
form, and functionality for hedging or screening. They should be used more often than they are because of their
hardiness and resistance to diseases and environmental stresses.

Ron Smith
NDSU Extension Horticulturist and Turfgrass Specialist
ronsmith@ndsuext.nodak.edu

TREES

Pine Needle Scale

    Although all pines and spruces in North Dakota are susceptible to pine needle scale, mugo pine and
Black Hills spruce are most often affected by this insect pest in our state. The insect overwinters as eggs
under white to pale-yellow, oyster-shaped scale coverings on needles. Tiny (0.3mm), red crawlers emerge
in May or June and feed nearby or are dispersed by the wind to another branch or another tree where they
begin to feed. Many infestations begin on the lower branches. The scales feed on sap, causing spotting of
needles. Premature needle loss may occur when infestations are heavy. Severe infestations left unchecked
can cause branches or even entire trees to die. A waxy coating, which is impenetrable to most pesticides, is
secreted as the insect feeds and grows. As the female lays eggs late into October, she will shrink and the
underside of the scale will fill with overwintering eggs.

    Christmas tree growers generally treat trees when they see five to ten scales per shoot. Delay treatments
of light infestations, since predators and parasites may curb scale populations. The crawlers, which are currently
active in the Fargo area, are the most vulnerable stage of this insect pest and are most easily seen on the needles
where scales were produced the previous year. Using alternative insecticides, such as horticultural oils or
insecticidal soaps, will help to preserve natural enemies of scales. Applications should be made when the tiny,
red crawlers are visible.

Marcus Jackson
Extension Forester
mjackson@ndsuext.nodak.edu