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ISSUE 3  MAY 20, 1999

TURF FERTILIZATION

    For those of you who have resisted the temptation of early lawn fertilization, congratulations!
You can now give in to your desire and carry out this task.

    We have seen the rains provide the turf with early green-up this month. Weather like this makes
everyone who takes care of grass, from the golf course superintendent to the average homeowner,
look like an expert. If you want to give your lawn something to help it through the summer months,
1 pound of nitrogen per 1000 square feet from a complete fertilizer will do the trick. Now the "trick"
is to get a quality material to put down, without being taken in by a low priced product.

    Quality lawn fertilizers today are poly-coated and sulfur-coated materials that are blended to contain
the precise nutrient content stated on the bag; e.g. 28-3-6. In looking on that bag, one could see that
the nitrogen comes from different sources - WSN (Water Soluble Nitrogen) and WIN
(Water Insoluble Nitrogen). The WSN is exactly what it says - water soluble - so that when the
material is applied and watered in (or shortly followed by a rain occurrence), it dissolves in the water
and is immediately available to the plant for uptake. The WIN form resists water solubility for some
time, becoming available to the plant over a period of 4-12 weeks. To get a balanced result, a quick
response to the application just made, and something later on, look for fertilizers that have between
10-30% of the nitrogen coming from WIN sources.

    In mowing my fields for the first time last week, I noticed some sod webworm moths zig-zagging
across the grass. Some of my bird sentinels (swallows) noted their flight and plucked a couple out
of the air. This is actually a form of flattery - to think that a female moth would select my fields to raise
a family in. Must mean she thinks a lot of my turfgrass care!

    Anyway, the sight of these insects should not be cause for panic, as their damage would be minimal
and essentially unnoticed in a typically well-cared for lawn. The lawns that it may make a difference in
would be those that will never receive supplemental irrigation or fertilization - in other words, subject to
other stressors. That female moth and her offspring will likely make a tasty meal for some foraging birds
- certainly better than applying insecticides.

    The tulips have all but completely faded, or will shortly do so. The question now becomes; "what do
I do with the remaining foliage and flower stalks?" Simple - cut off the stalks and allow the foliage to
remain until it completely yellows. The same treatment is true for other spring flowering bulbs - daffodils,
crocuses, and grape hyacinths. If you want to thin any or reset them to another location, wait until the
foliage has yellowed completely then carefully dig down, remove, and relocate. Be sure to keep track
of the colors! Mark the colors on the foliage with an indelible marker pen for now.

    A couple of questions have come in concerning vegetables already. Rhubarb flowering is nothing to
write home about - does it about this time every year. But, to maximize the energy going into the growth
of petioles, cut the flower stalks back before they have a chance to form seed.

    Another question came in that I thought was interesting concerning parsnip being poisonous if it wasn’t
harvested last year and is coming up again this year in the garden. While the Berula pusilla - water parsnip -
is considered poisonous, the garden parsnips, Pastenica sativa, are not poisonous at any time.

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

 

TREES

Ash Anthracnose

    The moderately-cool, wet weather seen across much of North Dakota over the last few weeks may
result in significant anthracnose infections and subsequent defoliation of ash trees. Currently, we are
seeing the water-soaked lesions associated with early infections accompanied by some defoliation.
The spots may coalesce to form large lesions on leaves which turn brown as they dry. Last year, ash
anthracnose caused significant defoliation in parts of eastern, central, and southwestern North Dakota.
Trees that lost up to 50% of their leaves in eastern North Dakota did recover by mid-summer last year.

    Multiple years of defoliation can stress trees. Fallen leaves and dead twigs should be removed in the fall,
especially from young trees. Rarely, the need for chemical intervention will arise. This is usually after
anthracnose has defoliated ash trees for several consecutive years. Three fungicide applications are generally
required for good control of this disease. The first application should be made as buds swell, the second
as the buds show green tip, and the third when the leaves are half grown.

 

Spruce Spider Mite

    Spruce spider mites have been active in Fargo since the end of April this year. Keep in mind that
spruce spider mites are cool-season mites and are often active very early in the growing season.
Mites will cause tiny yellow or white speckles on needles that can be seen with the naked eye and
are easily identified with a hand lens. We often notice damage during hot, dry summer days. The
feeding injury often occurred in the previous spring or fall and became evident under the stress of
hot, dry weather. Since miticides are usually more effective against adults than eggs, summer
applications of miticides are not usually effective.

    Mites are only 0.5 mm long and are very difficult to see without magnification. As with most
spider mites, a good test for spruce spider mites is to place a white piece of paper under needles
which are believed to be infested and tap the branch. Mites appear as mobile specks on the white
paper. Generally, if ten or more mites are found per sample, some type of control may be necessary.

    Syringing, cultural control, biological control, and chemical controls are all options that can be
used in controlling spruce spider mites. Spraying mites with a forceful jet of water (syringing) can
be an effective method for controlling mite populations in home landscapes while maintaining natural
predators. Lace wings and lady beetles are naturally occurring predators of spruce spider mites in
North Dakota. Insecticidal soaps can be used to manage spruce spider mites in warm weather,
while horticultural oils (1-2% rate) may be used during the summer and dormant oils (3-4% rate) can
be used to kill mite eggs and adults during the spring and fall. Horticultural oils can injure conifers if
applied when temperatures are not appropriate. Read the labels carefully. Miticides should be sprayed
when adults are active with a follow-up spray 7-10 days after the first spray to control later hatching
nymphs.

 

Tree Services

    As summer rapidly approaches, the need for tree care services will continue to increase. In North Dakota,
there are many tree care services that provide professional service at a reasonable cost. But problems
may develop when homeowners hire companies which are not properly insured, have poorly trained
employees, or are simply out to make a quick buck.

    Treatments are available for many of the tree problems seen today, but if treatments are improperly
administered, money may be wasted, trees killed, and neighborhoods polluted. When a reputable
company offers to treat a tree for a "bug," they will readily provide a homeowner with information
about the bug and should not discourage a homeowner from seeking a second opinion before
approving treatment of the problem. The second opinion can come from another arborist, the city
forester, the local Extension office, or the local Forest Service office. Homeowners may want to
research the problem themselves. Many of the common tree problems in North Dakota are
described in NDSU Extension bulletins and many libraries also offer good references for identifying
tree and shrub problems.

    The North Dakota Urban and Community Forestry Association provides testing for experienced
tree care professionals. If an arborist passes the exam and meets other guidelines required by the
International Society of Arboriculture, he/she will become a Certified Arborist. By becoming a
Certified Arborist, a tree care provider shows that he/she is experienced, carries a minimum level
of arboriculture proficiency, and is committed to his/her profession. In addition, some communities
require anyone providing tree care services within the community to pass an exam to show that
they are knowledgeable arborists. Homeowners should contact their city foresters to determine if
their communities require this type of testing and if a particular tree care provider has been approved
to complete treatments.

    The number of years required for a tree to reach maturity must be considered when deciding
whether or not to allow someone to treat it for an insect or disease problem. Treatments may improve
a tree’s health if done properly; whereas, if done improperly, treatments may significantly reduce a tree’s
aesthetic value and longevity.

Marcus Jackson
Extension Forester
mjackson@ndsuext.nodak.edu


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