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June
3, 2004
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: Are crab apple
trees toxic to horses? (e-mail reference)
A: There have been
no reported toxicities. Trees sprayed with pesticides would make them
toxic.
Q: I planted a spirea
last summer that is doing well. Could you tell me what to fertilize it
with? I was told to use a 5-10-5 slow release formula that would promote
healthy growth and strong roots. I can’t get it at our local stores
or greenhouse. Does it need anything now or in the fall? (Lankin, N.D.)
A: The fertilizer
the company suggested is older than I am! It is a good one for establishing
plants and not over-stimulating them. You can use any fertilizer that
you can find locally. 10-10-10, sometimes known as a garden fertilizer,
is one of them. Another is Miracle-Gro, which seems to be readily available
at most garden center outlets. I’m glad your plant is off to a
good start. A shot of fertilizer will help it along.
Q: Two years ago,
I planted six pygmy globe arborvitae in front of our church. They are
spaced about seven feet apart. It is 36 inches between the church and
sidewalk and they are on the east side of the building. Last year one
started turning brown. I replaced it a few days ago. Now the other five
are starting to turn brown. I have tried to water about every 10 days.
I sprayed with Malathion and applied Miracle-Gro twice last summer. The
ground is covered with plastic with small rock on top. (Kathryn, N.D.)
A: Your problem
is the plastic/rock cover. Take it off as soon as possible and leave
the soil bare. Mulch with bark (2-3 inches) if you have to. The rock/plastic
combination deprives the root system of air and causes a gradual plant
decline and death.
Q: I have a yellow
rose bush that has always produced beautiful yellow roses. This year it
is beginning to bloom but the buds are all scarlet red! What in the world
is going on? I have not touched this bush since last fall when I pruned
it. Any explanation?
(e-mail reference)
A: Unless the new
growth is coming from below the graft union, I have no explanation.
Sometimes the buds are a different color than the open flower. Sorry
I cannot help you more!
Q: We planted a hedge
about three years ago. The last few years I have not weeded out the grass
so now the grass is about a foot high around the plants. I started to
cut the grass out by hand and replace it with new soil, but this is very
difficult and I have 50 feet of hedge to do. Is this the only solution
or is there something I could spray on the grass to kill it that would
not harm the shrub? (e-mail reference)
A: Look for a product
known as Vantage. It will control most all the grasses you have growing
in the cotoneaster hedge. That is much easier than trying to hand weed
50 feet of hedge!
Q: Is there something
I can put on my garden and flowers to keep cats away? (e-mail reference)
A: Your question
is common, but difficult to answer. Try to find out if there is a leash
law in your community. If there is, tell the owners that if they don’t
comply with the leash law, you will notify animal control. If they are
wild cats, they should be rounded up by animal control.
Or you can purchase a roll of concrete reinforcing wire and lay it across
the entry points to your planting area. Spray it with Re-pel, anise
oil or Eucalyptus oil. Cats find stepping between the openings an annoyance
and that coupled with the smell will drive them away. You can place
pieces of cardboard with Tanglefoot applied. Cats step in it once and
leave quickly! Get a scarecrow impact sprinkler that is motion controlled.
It comes on loudly, runs for about 10 seconds in an arc and scares the
cats away. These are the best suggestions I have.
NOTE: Ron Smith is on vacation for two weeks and the following responses
are from Joe Zeleznik, Extension forester and Todd Weinmann, Cass County
Extension agent.
Q: I need some advice
on how to properly prune crabapple and regular apple trees. I ordered
some trees from a nursery catalog and the trees I received came with quite
a few branches. Should I remove most of the branches so there are only
three or four left? Should I remove bigger branches that are closer to
the ground in favor of the smaller ones up higher? The trees are roughly
four to five feet tall. (e-mail reference)
A: In the old days,
we used to recommend pruning trees at the time of transplanting, but
we've found out that doing so can cause more harm than good. The leaves
that will come out this year and be displayed on those current branches
are vital to the tree as it establishes itself in the new site. I would
hold off on pruning for one to three years until the trees really get
established. When you do get to the structural pruning, it's important
to keep a few things in mind. Never prune more than a quarter of the
branches at any one time. The tree needs those leaves to harvest sunlight
and convert it to food energy. If the tree loses too many leaves at
one time, it will take a long time to recover. Wide branch angles are
preferred, at least 30 degrees away from the (vertical) main stem. It
would be even better if they were between 45 and 60 degrees. Keep the
main structural branches spaced about 18 to 24 inches apart along the
main stem. If you want some more information on pruning, NDSU has an
excellent publication online at: http://www.ext.nodak.edu/extpubs/plantsci/trees/h1036w.htm.
(JZ)
Q: We have a 17 foot
corkscrew willow on a raised portion of our yard next to a waterfall and
the entrance of our home. It is a gorgeous setting with a perfect look.
Unfortunately, because of the position of our house, it catches north
and south winds. Last winter the freezing winds caused some frost damage.
The majority of the branches are now dead. Are there any similar trees
that don't grow more than 20 feet tall with these characteristics that
would be hardy for our region and the position it would sit? Where would
we locate a tree like this? (Sioux Falls, S.D.)
A: There are a couple
of different willows that grow to about 20 feet and should be hardy
in your area. French pussy willow, Salix caprea, also called "goat
willow," is hardy in Zones 4-8 (you're in zone 4). Pussy willow,
Salix discolor, also called common pussy willow, is native to eastern
North America and is hardy down to Zone 2. Flame willow, Salix flame,
a hybrid willow that's hardy in Zones 3-6, has dense branching and a
red-to-orange twig color in the winter. We have a windbreak with these
here in Fargo and it's very effective (dense branches) and attractive
in the winter. There are probably many others that I'm not aware of.
All three of these willows are grown by Bailey Nurseries, a large wholesaler
in St. Paul, Minn. Your local retail nursery or garden shop may have
them in stock or could order them for you. Good luck with your trees!
(JZ)
Q: We have two very
tall cottonwoods in our front yard. For about three years they have been
losing chunks of leaves during the summer. I contacted many people but
they gave the same answer that you did; this is normal. We now have more
dead branches then live and they look awful. One Web site I went to said
shoot blight could be the problem. The clumps always had a black glob
on them. (e-mail reference)
A: Based on what
you described, it does sound like leaf blight and/or shoot blight. A
professional diagnostic lab could culture a sample and let you know
for sure. And yes, normally this doesn't cause major damage unless it
occurs on the same branches for several years, as you indicated. Prune
out the dead branches and rake and remove the infected leaves each fall.
Copper-based fungicides may provide some protection, but you may not
be able to provide adequate coverage if these trees are already very
tall. Good luck. (JZ)
Q: I have a lilac
tree that I planted under my kitchen window three years ago. I have been
waiting for buds to pop, but so far no luck. The reason I planted the
tree was so the aroma of the lilac would come into my kitchen. Am I just
not waiting long enough, or is there something I can do to help it along?
(New Jersey)
A: Tree age really
doesn't matter when it comes to flowering. It is actually a tree's size
that determines when it flowers. These lilacs may not be big enough.
Too much nitrogen fertilizer may also be affecting them. When trees
have too much nitrogen in the soil, they put a lot of energy into growth
rather than reproduction. Also, lilacs prefer full sun and a well drained
soil with a pH close to neutral. (JZ)
Q: My mom always had
a pussy willow tree in her yard. Since we recently lost her, I wanted
to plant one in my yard in her memory. I received some branches from a
friend and they are currently in water to root. Is this the correct procedure?
Does the tree need anything specific in terms of sun, food, etc.? (e-mail
reference)
A: Willows generally
need a lot of sun and water. Once the cuttings take root, you can transplant
them to pots or directly into the ground outdoors. Be careful not to
damage the fragile roots that developed in the water. Most willows will
establish themselves directly in the soil from dormant hardwood cuttings.
All you need to do is to cut a piece of a twig, at least 10 inches long,
from a branch that's dormant, before bud break in the spring. Stick
it in the ground with the buds pointing up. That is all you need to
do. The farther it is in the ground, the better, as the cutting will
initiate roots all along its length, where ever its in contact with
the soil. Good luck! (JZ)
Q: Can you tell me
the name of a supplier for an Indian summer crab apple tree? (e-mail reference)
A: One wholesaler
is Bailey Nurseries in St. Paul. They can be reached at (800) 829-8898
or via e-mail at plants@baileynurseries.com.
Their Web site is www.baileynurseries.com.
They can give you a list of retailers that they supply in your area.
Another wholesaler to check with is J. Frank Schmidt and Sons at (800)
825-8202. Their Web site is http://www.jfschmidt.com.
Good luck with your trees! (JZ)
Q: We just dug out
100 feet of cotoneaster bushes. I now need to find something to replace
them. What would you suggest? I don't want anything that gets over 5 feet
tall and I would like to have something that the birds like but not the
deer. These bushes have to be hardy and wind resistant. The hedge we had
in this area was full of diseases. Will that affect any other bushes that
we might plant there? We still have some cotoneasters that are full of
disease. Will these diseases spread to the new ones? I am wondering about
a Russian almond. (Tappen, N.D.)
A: There are a whole
variety of shrubs that survive well in our area and are dense enough
to provide good habitat for birds. However, I have yet to find the tree
or shrub that's totally deer resistant. The hard part is going to be
finding something that stays under five feet and will take the shearing
that is common in a traditional hedge. Meadlowlark forsythia is an NDSU
introduction and may be a good choice. It should form a fairly thick
hedge. Some of the honeysuckle cultivars would probably do well, too,
although they may not respond as well to shearing. They also will get
taller than five feet. Red-osier dogwood is very pretty in the winter
and provides good cover for birds. However, it's more of a wide-spreading
shrub and is not really meant for a traditional hedge. There are a lot
of other shrubs that are hardy in your area, but as I mentioned, the
five foot height limitation and the ability to take shearing are going
to limit the selection. Check with your local garden center for some
ideas, and maybe Ron will have some more ideas when he returns. Your
question about the disease spreading to newly planted shrubs is an excellent
question. It depends on what the disease actually is. My guess is that
the cotoneasters are suffering from fireblight, a bacterial problem.
Fireblight commonly affects apples, crabapples, mountain-ash, cotoneaster
and hawthorn. It's pretty specific to these species.
Having said that though, I just want to say that no plant is completely
pest-free. Every tree or shrub will have something that attacks it.
Some, like the cotoneaster, are less resistant. The trick is to find
the ones that are more resistant to pests. Regarding Russian almond,
I don't have any direct experience with it, so the following is pretty
much straight from the books. Russian almond will survive well in N.D.
and it appears to not have any major pest problems. However, it suckers
a lot. That's great for a hedge, up to a point. It provides great wildlife
habitat, too. The suckering might be kept under control by using a woven
landscape fabric, which is commonly used in plantings by the Soil Conservation
District. They should be able to give you some more insight on its use.
(JZ)
Q: A friend of mine
is moving to Canada and cannot take her very large and tall ficus tree
with her. We recently transported it to my home, where it sits in an indirectly
lit room. It was doing fine for about one week and then, over night, it
went into shock. I'm sure the shock is due to some pruning she did so
it would fit into my house, as well as the 20 minute drive to my home
(lying down in the bed of a truck). I would hate to lose the tree. Is
there anything I can do? I fertilized it with Miracle Grow diluted in
water the day before it went into shock. (e-mail reference)
A: Ficus is a tropical
plant so cold air drafts are not good for it. Make sure you don't over-water.
It's a common tendency that kills plants. Get some artificial plant
lights directed on the remaining foliage. Your plant is likely in a
different light situation compared to where it came from. Ficus is typically
raised on high intensity light (1000-foot candles or more) with a combination
of artificial and natural light. When brought into a home, they are
lucky if they get 250-foot candles of light. This major reduction in
light causes the yellowing and dropping of the foliage. If it is too
low, the low light intensity and duration will cause crown thinning
(die-back of branches) until there is a balance of foliage to available
light. Based on what you have told me, this is the best advice I can
give you. (TW)
Do you have a gardening
or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension
Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu.
Note to e-mail correspondents: please identify your location (city and
state) for most accurate recommendations.
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Source: Ron
Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Source: Joe Zeleznik, (701) 231-8143, joseph.zeleznik@ndsu.nodak.edu
Source: Todd Weinmann, (701) 241-5707, tweinman@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu
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