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August
4, 2005
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: When I bought my
schefflera plant at the green house, they sprayed something on it to make
the leaves shinny. Is there something I can put on the leaves to bring
the shine back? (e-mail reference)
A: The material
is called “Leaf Shine.” Imagine that! Be careful not to
overuse it because it tends to seal the stomatal openings and slow the
plant’s growth somewhat. You might want to learn to appreciate
the “natural look” of this plant and shine it up only to
impress company.
Q: I recently received
a begonia, which I repotted and placed in front of a sunny window. Over
the past couple of weeks, it has been flowering profusely, but its leaves
have begun to shrivel. It is producing new leaves, but even some of those
are withering. It has plenty of water. In fact, I
believe I have overwatered it. (e-mail reference)
A: Sun and begonias
usually don’t make a good combination. I would suggest moving
it to the side or back a little from the window so that it doesn’t
receive direct sunlight. Also, keeping the soil media moist and keeping
it wet are two different conditions. Moist is good, wet is not, so back
off on the watering. If these two actions don’t result in some
improvement, then it is something else causing the problem.
Q: I had a rhododendron
that did not make it through the winter. It was fine in the fall and had
beautiful blooms. It was on the south side by a fence and got afternoon
sun. I dug it up and found small green balls in the soil. I did not fertilize.
In addition, the hydrangea I planted last year did not grow back very
well. I had aphids last year, but I sprayed. What can I do to make them
healthy and what would cause my rhododendron to die? (e-mail reference)
A: Don’t plant
rhododendron in direct sunlight and be sure to modify the soil with
a lot of sphagnum peat moss. I would suggest a little more patience
with both. Give them a shot of Miracle-Gro when growth begins.
Q: While visiting
my daughter, I noticed what I think is scale (small, scabby-looking brown
things concentrated on leaf bottoms with a few on the tops and lower stalk).
These are in a large and otherwise healthy looking pittisporum. I roamed
around your Web site and read the questions and answers, but I didn’t
find a specific description of scale or how to get rid of it. Can you
give me some advice or direct me to the proper Web site? (e-mail reference)
A: How negligent
of me not to have more descriptive information on my Web site on one
of my favorite plant pests, soft and armored scale! Soft scales usually
are not a big horticultural problem because there are many natural controls
that keep them in check, such as parasitic wasps and lacewing larvae.
In addition, they can be checked in their progression by a hard rainfall
or a good washing from a garden hose. Horticultural oils are among the
most useful treatments of soft scales on outdoor and indoor plants.
The armored scales, which is what you seem to be describing (the oyster-shell
species), are equally susceptible to natural predators in the early
stages of their lives and to horticultural oils as well. However, once
the armor scales are in place, these pests become particularly difficult
to eliminate or bring under control. If they are confined to just a
few branches or leaves, it is best to prune those off and dispose of
them. Then spray the rest of the plant. Spray the upper and lower foliage
surfaces with just about any insecticide to take care of any immature
crawlers that may be considering establishing a home on the plant. Some
control can be obtained by scrubbing with a pot scrub brush to disrupt
them from the stems and leaves. While pittosporum is a tough and durable
species and probably can carry a few scale or mealybugs, which they
seem to be more prone to, it is best to bring any recognizable pest
under control as soon as possible with the least toxic method possible.
Q: We are thinking
of planting 20 to 30 chokecherry trees on our property, but it sounds
as though they have many disease and mildew problems. Is this correct?
I’m also wondering why you did not suggest bacillius thuringiensis
to control tent caterpillars and webworms. I have had great success with
it on other trees. (e-mail reference)
A: There is a fungus,
black knot, which has become so rampant that I no longer can suggest
it as a landscape plant without a twinge of guilt. I have recommended
Bt (bacillus thuringiensis), but it probably has not made it into the
Web site’s history. People want a “shot between the eyes”
as far as treatments go, so many are not patient enough to wait for
the insect to get sick and die. People want to see results within seconds
after spraying! I just hope they are careful. To make it official, I
hereby declare Bt effective on all caterpillar stages of insects feeding
on trees. To date, as far as I know, it is the only microbial insecticide
in wide use for horticultural crops and is safe for use around warm-blooded
animals. Thanks for writing.
Q: I have a number
of tulip and daffodil bulbs. Some are dry and some are in pots. I’d
like to get them into the garden. I know that one is supposed to plant
them in the fall, but what would happen if they went into the ground now?
Would the bulbs die, rot, never bloom again or what? (e-mail reference)
A: I don’t
know, so take your pick. If you can, try to keep them dry and cool for
now, and plant them in September. Then hope for the best next spring.
I think everything will turn out better for you if you can wait until
then.
Q: I read the questions
on your Web site, but didn’t find this one. The cyclamen I have
appears to have a seedpod growing. It’s a round thing on the end
of a stem and is hanging over the edge of the pot. I’m interested
in trying to grow a plant from seed, but I’m not sure when to remove
the pod, how to remove it correctly or how to plant the seeds. Can you
tell me what to do? (e-mail reference)
A: Allow the pod
to remain until it dries. If you want, place a bag over the pod to catch
the seed in case it opens before you get to it. It is a challenge to
grow cyclamen from seed because it needs to germinate in the dark and
at soil temperatures between 68 to 72 degrees. Germination takes four
to six weeks. Use a peat-based medium and RO or distilled water. Expect
it to take several years to get them to bloom, if at all, so I hope
you are a patient person!
Q: In a store, I found
one of the most perfect and beautiful roses I have ever seen. I have been
trying to find where I can purchase the bush. The name of the rose is
red intuition. The House of Del Bard bred it in 1999 in France. It is
a descendent of the red painter rose. (e-mail reference)
A: This is a florist
rose and may not be available to the gardening public. It can be grown
anywhere from Oregon to South America or even in Holland greenhouses!
While it may be a majestic, drop-dead beauty in an arrangement, as a
garden rose bush under typical conditions, it may be a loser. I don’t
know. I would suggest attempting to contact the Society of American
Florists or the American Rose Society to see if they can lead you anywhere.
They should be able to give you a definite answer.
Q: Last evening I
noticed tearlike droplets on the tips of my dieffenbachia. When I checked
further, there also was an accumulation of the clear liquid in several
places on some leaf surfaces. The weeping continued after I tried to soak
up the liquid with a paper towel last evening, but seems to have subsided
at last check. Is this a phenomenon that you are familiar with and does
it indicate the plant is stressed? Otherwise, the plant looks healthy
and has put out a number of new leaves in recent weeks. (e-mail reference)
A: This is a perfectly
normal function of the plant. It is exuding the carbohydrates from the
openings on the leaf surface while the plant is fully turgid. On the
surface, those openings are known as stomata. On the leaf tips, they
are known as hydathodes. In essence, this is a fat and sassy, well-cared
for plant. It is so well-cared for that it is drooling all over the
place!
Q: I have two rows
of asparagus with annual weed (kochia, pigweed and sow thistle) problems.
Is there an application that I can use to control these weeds and not
harm the asparagus? In addition, my neighbor and I have beds with a prickly
pear-type cactus that are infested with quack grass. Is there anything
that will remove the grass without killing the cactus? (Glenburn, N.D.)
A: Try Vantage in
the cactus beds. For asparagus, go to http://web4.msue.msu.edu/veginfo/bulletins/E433/index.cfm?crop=101
for more information. Generally, any weed control has to come before
the asparagus emerges or after it is heavily frosted in the fall.
Q: I just purchased
arborvitae and American evergreen trees and received 10 free French lilacs
with them. My husband and I are starting a tree garden and eventually
will move them after our home is built. Can we plant these together? Can
you send me some information on caring for French lilacs? (e-mail reference)
A: Why not just
speak “French” to the French lilacs and only use the finest
fertilizer from the Bordeaux valley of France! Just kidding. I felt
like being silly after a long day of answering questions! Actually,
the French lilac is any number of so named cultivars of the original
syringa vulgaris. They came from the Balkans, where winters can be harsh,
summers dry and rocky soil the norm. Our climate mimics their origins
and they have survived for a century or more throughout the country.
Napoleon cultivated lilacs in his royal gardens, so they came to this
country as a “French” lilac. Lilacs don’t like to
be kept too wet, need full sun, little fertilizer and careful pruning.
That is assuming you want to enjoy the flowers that have made them so
famous. Prune right after flowering if it is desired or necessary to
do so. Other than that, they just need to be admired for the beauties
they are. Enjoy!
Q: What would be the
proper weed killer to use on weeds that are overwhelming a raspberry patch?
(e-mail reference)
A: To control a
weed, one needs to know what it is. Grassy weeds can be controlled with
Vantage, while broadleaf weeds are a little more difficult and the control
needs greater care in application. Look at the labels for Roundup, Devrinol,
Princep and Simazine. All are labeled for weed control in raspberries,
but have limitations as to the timing. In raspberries and strawberries,
you are better off taking control of weeds using mechanical means, which
is good, old-fashioned hoeing!
Q: If you were to
attempt to grow pears in the Jamestown area, what varieties would you
select and what cultural practices would you suggest? (e-mail reference)
A: First, I would
hope that I had better luck than I did growing them in Fargo! I grew
Parker and Luscious. Both varieties are reputed to be good-tasting pears,
but both succumbed to fireblight and a terrible chlorosis, not the winter
cold. I have had better luck with apples and plums. Here is the pedigree
on the two I attempted. Luscious is from South Dakota. It bears medium
to medium-small fruits in mid to late September and has a flavor similar
to Bartlett, but more intense. Its texture is firm, but melting. Like
Gourmet, Luscious reportedly is somewhat resistant to fire blight and
is pollen-sterile. Parker is an older University of Minnesota release
(1934). Parker produces fruit similar in size, flavor and texture to
Bartlett. It is somewhat less hardy than other varieties. It may not
grow well north of the Twin Cities. Harvest in mid-September. I would
grow Summercrisp, if I were to attempt to grow a pear again and could
weasel some garden space from my wife. Summercrisp is the most current
introduction from the University of Minnesota. The university released
it in 1985. It produces medium-sized, red-blushed fruit that is mild
and sweet with a crisp texture strongly reminiscent of an Asian pear.
Summercrisp is hardy in most of Minnesota and moderately resistant to
fireblight. An early variety, it is harvested in mid-August.
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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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