NEIGHBORHOOD GARDEN FOR
DECEMBER 15, 2007
PINE WILT (PART 3: HOW TO
SELECT & PLANT A NEW TREE)
BY GEORGE EDGAR
Over the past 20 years PINE
WILT has killed so many Scots or SCOTCH
sylvestris) trees in the Midwest that Extension Specialists and arborists in
many Midwest states no longer recommend planting this once popular
species as a landscape or windbreak tree. Some experts even predict that
we will not have any Scots
pine trees in eastern and central Nebraska within 5 to 10
years. No cure has been found so far. High value trees can be protected
with a series of trunk injections of Greyhound (abamectin is the active
ingredient). This is a preventative treatment and very expensive.
species are occasionally killed by pine
wilt and display a similar pattern of symptoms. The disease
appears occasionally in Austrian pine (Pinus
nigra), Jack pine (Pinus
banksiana), Mugo pine (Pinus
mugo), and Red pine (Pinus
resinosa). It is rarely found in White
pine (Pinus strobus) and never found in spruce, fir, juniper, or red
influences the risk of pine wilt. Almost
all cases of disease have appeared in trees more than 10 years old.
wilt has not had a major impact on Christmas tree plantations
pine or Austrian pine.
In Part I, I
wrote about this fatal disease of pines in the Midwest, the pinewood
xylophilus), and the pine sawyer beetle (Monochamus carolinensis) that carries the nematode. I also mentioned
that the disease has been found in some Austrian Pine trees.
In Part II, I described some trees that could be used as replacements
for the Scots
pine and Austrian
pines. Today I want to talk about how to decide what tree to
plant and how to plant that tree. This section is also applicable to
deciduous trees that lose their leaves) as well as conifers. As with
Part II most of this material comes from the Nebraska Statewide
Arboretum and an article by Justin Evertson.
He recommends: “Before
selecting that replacement tree (or a new tree for your landscape), get
some ideas from established landscapes:
Drive around and see if you can find a tree you like.
Pay attention to what you like and what you don’t like. Also
pay attention to height, width, form, and seasonal color if any. You may
want a dwarf variety so it does not outgrow its space.
Be sure and pay attention to drainage in your landscape and where
you want to plant the new tree so it does not sit in water after a rain.
Can the tree stand dry living conditions, or does it need lots of
water? And if in the lawn, will it tolerate a sprinkler system? Your
grass takes a lot more water than most trees like.
Find out if the tree you like needs full sun, partial sun, or
You may want to get a soil analysis so you know that the tree you
like will survive in your yard or acreage. Making any changes after a
tree is planted is almost impossible.
When planting your new tree, do not plant too deep. Dig your hole
just deep enough. Do not go any deeper or roughen up the bottom of the
hole. If you do the root ball will settle and be too deep. Dig your hole
at least twice as wide as the container or “balled and burlapped”
root ball. The first root should be only two inches below the surface of
the soil. If necessary remove some of the soil from the top of the root
ball to find the first root. If you see a tree coming out of the ground
like a utility pole, with no flair at soil level, it is planted too
deep. Trees planted too deep will always be under stress and will more
likely have disease and insect problems.
Add wood chips around the tree. Go out at least two to three feet
from the trunk. This will help to retain moisture and keep the roots
from drying out.
Do not try and grow grass up next to tree. This stresses the tree
and makes the trunk more likely to be damaged by a mower or weed whip.
“When planting evergreens, remember that most species prefer
well-drained soils. In fact most evergreens will struggle in heavily
irrigated, turf-dominated yards. In addition, evergreens almost always
work better in groups, as backdrops or as framing elements. Be careful
if planting in the front yard especially near sidewalks, intersections,
or picture windows where they might eventually outgrow the space.”
When planting any new tree, measure the space to make sure that
the mature height and width of the tree is not too big for the site.
Many times that small tree is placed too close to the house or another
structure. Read the tag on the tree and measure to make sure. When I
planted the Colorado Blue Spruce in my front yard, I measured out from
the house so I knew how much room I had to the sidewalk. The small tree
looked lost but now, 40 years later I am glad I did the measuring.
New trees need to be watered in, but be careful, as many new
trees are killed by over watering. Before watering your new tree, make
sure the soil is not saturated from the previous watering. Also, check
to make sure that the roots do not dry out. If you plant a tree and then
go on vacation, make sure someone is checking on the tree and waters as
I want to thank Justin Evertson
again for permission to use his articles in this series, and for
reviewing and correcting the information. For
more information on tree selection, tree planting, and tree care, you
can reach Justin and the Nebraska Statewide Arboretum on the
internet at “http://arboretum.unl.edu”. Also at this web site are
links to colored pictures of trees.
You can also
contact your County Extension Educator or go on line to www.ianrpubs.unl.edu.
On the left hand side you can type in the name of a disease or the name
of a tree then click on search. A list of publications will appear. You
can read those you want and/or download them to your computer or print
them for your files.
Or you can go
to www.nfs.unl.edu. This is the web sight
for the Nebraska Forestry Service which is a division of the University
of Nebraska-Lincoln. In the upper left hand corner in the search box
type in “pine wilt” or the name of the tree you want information
about. A list of publications will appear. You can read those you want
and/or download them to your computer or print them for your files.