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April
15, 2004
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: I have two jade
plants that need help. One is covered (leaves and stems) with what appears
to be waxy scales. The scales aren't bumpy and don't wipe off. The other
plant has raised black spots on the leaves. I can take them off with a
fingernail, but when I do, they leave a pit on the leaf that later dries
and turns white. (E-mail reference)
A: Some scale insects
wipe off fairly easy, while others have to be scraped off with the edge
of a fingernail or knife. I suspect scale on the stems and possibly
on the leaves. If you can, try to scrape or wipe those bumps off with
your thumbnail or the edge of a knife to verify you have scale insects.
If they are not, then I have no idea what the problem is. I suggest
taking a sample and sending it to the local land grant university in
your state and addressing it to the Plant Diagnostic Lab. If your county
has an extension office, take a sample directly to them for possible
identification.
Q: I have read conflicting
advice on how to prune clematis. I have a red trumpet vine, alpina clematis
and Montana clematis. The tags seem to say two different things in regard
to pruning. Do I prune after flowering in the summer or in the dead of
winter? (E-mail reference)
A: Simply follow
the tag directions. Some clematis should be pruned now, in early spring,
while others that bloom in late spring can be pruned back right after
flowering. If it is from the Jackman group, which is the largest and
most popular group in America, then pruning can take place this spring
as the buds begin to swell. My advice on following what is said on the
individual tags comes from the fact that I have no specific information
on the names of the clematis you provided.
Q: I have started
watering spruce trees that I planted last fall. Is this going to be beneficial
to the trees even though the frost isn’t completely out of the ground?
(E-mail reference)
A: Frozen ground
cannot take up water. By keeping the upper region of soil saturated
with water, you are essentially creating a condition which encourages
surface rooting. For woody plants, herbaceous plants and turfgrass,
I recommend that water be applied as the soil dries. This encourages
the roots to penetrate deeper following the receding water. In a perfect
world, all plants should be watered just before they undergo drought
or water stress.
Q: You spoke about
spraying fruit in the spring with oil. Is this the time and what kind
of oil should I use? I have apricot trees that yielded abundantly last
year and I'd like some more jam. (Brookings, S.D.)
A: Now is the time.
Get Horticultural Oil that can be used any time of the year. You can
get it at any garden supply store.
Q: I have a birch
tree that woodpeckers are pecking full of holes. What can I do to stop
them and how do I repair the tree? Also, I have a silver maple on the
west side of my house that has stopped growing the last three years. It
is 25 feet from two other maples planted at the same time. The other two
are doing fine. All are about 25 feet from the house. The problem tree
outgrew the others for the first four to five years. It will green up
but the only new growth is on the lower part of the tree and is minimal.
Its leaves are only half the size of the other trees’ leaves. I
tried foliar feeding with Miracle-Gro a few times last summer, but it
did not seem to help. (E-mail reference)
A: You will have
to draw on your creativity to control the woodpeckers. Some people get
good control with Tanglefoot, aluminum foil, or a stuffed owl or falcon
in the tree. Woodpeckers are very intelligent birds and not easily fooled,
so you will have to draw on a mixed bag of tricks. I suspect a root
rot problem with your silver maple. You might want to call in an International
Society of Arboriculture certified arborist to see if there is any remedial
action you can take to save the tree.
Q: I want to plant
some poplar trees where spruce grew for 30 years. There is a thick bed
of pine needles in the area. Someone told me nothing will grow in that
area. Also, I want to transplant asparagus. Does transplanting require
any special care or consideration? (E-mail reference)
A: The spruce needles
make excellent mulch. While in place, very little will emerge from the
nice thick mat that has developed over the years. If you pull the mat
of needles back and plant into the rich soil below, I'm sure the poplar
trees will establish themselves and grow if given proper care. Move
the asparagus as soon as reasonably possible. Set the crowns about six
inches below the surrounding soil, with ample compost, peat moss or
rotted manure. Be sure it is planted in a full-sun location.
Q: I have purchased
several 75 foot long soaker hoses. The label says a hose will emit one
gallon per foot per hour at low pressure. How far will water soak into
the ground on each side of the hose? I want to space the hoses the proper
distance apart so I can be assured that all the plants get enough moisture.
Also, how many hours should I water for deep soaking and how many times
per week? The soil is fairly sandy soil so I have good drainage. (Cooperstown,
N.D.)
A: Sandy soil has
good vertical percolation rates but not very good horizontal hydraulic
conductivity. You will have to experiment with spacing to see how far
it will spread. I suggest starting out with the hoses about 12 inches
apart. Keep in mind that what you see taking place on the surface will
not equal what is going on below the surface. Water in sandy soil follows
a fairly narrow path down through the profile. Clay soil spreads out
in a "belly" like fashion. As far as timing, I would suggest
leaving it on, initially, at least for three hours. After that, check
to see how deep the water penetrated into the soil and how far it spread.
How often you water depends on whether or not the beds are raised, in
full sun, facing south, exposed to prevailing wind forces or if you
mulched. I suggest mulching to conserve water and control weeds.
Q: Is there a local
arborist I can call? I live 20 miles south of Fargo? (E-mail reference)
A: Try calling Kelly
Melquist at (701) 729-6899 or James Danielson at (701) 729-7208. Both
have done excellent work for me and get my highest recommendation.
Q: I have a President
Grevy lilac that has healthy foliage, but I only get one or two blooms
(if any). It is at least 15 years old and planted in full sun. I have
limed the ground to sweeten it and fed it bulbtone fertilizer. What else
can I do to get it to bloom? Also, last summer some bees attacked my lilac
every day and fed on the bark. They would leave late afternoon and return
the next day. The bees were dark brown in color. Do you have any idea
what they might be and what I can do so that I don't have this problem
again this year? (E-mail reference)
A: You might try
some rejuvenation pruning this spring before leaf-out takes place. The
bees may be "cutter bees" that cut loose bark and leaves for
their nest. They generally are not a problem. If they come back this
year, follow them to their nest and possibly have them exterminated
by a professional if they pose a threat to anyone's health.
Q: Is there anything
I can do to get rid of grass growing in my perennial flower bed? The daffodils,
poppies and columbines are coming up, along with the grass. I also pulled
out some junipers next to my flowers. Can I plant flowers in the same
spot or is the soil too acidic? (E-mail reference)
A: There are several
products that are effective, but your planting mix may nix it by not
being labeled for those particular plants. Visit your local garden center
and see what is available. Most are effective when everything has been
cleaned up. After clean up, a pre-emergent like Surflan can be put down.
You can plant in the same location where the juniper existed.
Q: I live in Florida
and want to send a plant to a friend in North Dakota. It would need to
thrive on a balcony during the warmer months and indoors the rest of the
year. Any suggestions as to what might work? I mistakenly sent a Norfolk
Island pine two years ago but of course it eventually died. I would like
something that might bloom. (E-mail reference)
A: Try a hibiscus.
They seem to make it outdoors during summer and survive indoors through
winter.
Q: I remember your
column of a year ago that had some cautionary notes about advertisements
for Zoysia grass plugs. It seems to me you indicated that it is difficult
to establish a lawn using this product. Can you repeat your advice? Would
you recommend another product that is more suited to our hot, dry summers?
Should I use a herbicide or pre-emergent to get rid of my weeds? I would
like to use as few chemicals as possible. (Mobridge, S.D.)
A: Zoysia plugs
get good press but poor results in our area so avoid them no matter
how good they sound. Fairway or roadway crested wheat grass is a good
alternative to use in the hot, dry part of your state. If you are over-run
with weeds, kill them off this spring with RoundUp and reseed with grass.
Water in and keep it moist. It will establish quickly.
Q: I have a new residence
with a sodded lawn. The grass was in excellent shape going into last winter.
As the snow melted, I noticed a lot of damage on the grass. The grass
has been chewed off and bunched up in several locations. As the snow was
melting, I noticed a mouse like creature along the side of a snow bank.
Can you help identify the nature of the problem and the creature causing
the problem? Will the lawn recover? What can be done to eliminate the
creatures? (Moorhead, Minn.)
A: What you are
seeing is a vole, a mouse-like creature that tunnels under the snow
through the grass leaving little trails or pathways. Don't feel you
are the only person with this problem. Voles tunnel through many lawns,
including mine, every winter. Rake the lawn with a leaf rake this spring;
then give it a light application of fertilizer after the first mowing.
The beauty of Kentucky bluegrass is its high ability to recover from
such treatment along with compaction, insect and disease damage. I wouldn’t
worry about trying to eliminate the little pests. They disappear during
the summer months because of predators or shyness. This coming fall,
cut your grass about one inch shorter than you did during the summer.
Also, clean up any leaf residue and debris that could provide cover.
You can try poisoning and trapping, but I would rather let nature take
care of things unless it gets out of hand.
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
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu
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