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February
23, 2006
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: I am forcing some
tulip and crocus bulbs. I have the bulbs in potting soil and stored in
a cold, dark place. The bulbs are starting to sprout, but there also is
mold forming on the top of the soil on one of the pots. It is a light,
cottony mold. I think one of my mistakes is that the soil is a little
too moist, which I am sure promotes mold growth. Is there anything I can
do to kill the mold? (e-mail reference)
A: This is just
a saprophyte feeding on the organic matter and usually is not a pathogen
to the plant. You can scratch the surface of the soil to loosen it and
aid in drying it out. I wouldn't apply any fungicides because they’re
not needed in this case.
Q: I had a problem
with my carrots last year. When I harvested the mature carrots, there
were holes in some of them. The ground over the carrots was not disturbed
and I didn't see any tunnels leading up to the carrots. The sides of the
holes appeared to be smooth. The carrots were healthy despite the holes.
I began noticing the holes Aug. 1 and continued to notice them until I
was done harvesting. Any idea what did this? (Driscoll, N.D.)
A: The symptoms
you describe don't fit the pattern of the three most common insect pests
of carrots that I know of. The three pests are the carrot rust fly,
aster leafhopper and carrot weevil. What could be causing the problem
is slugs because there was no tunneling or frass present. These critters
often will leave nicely chiseled holes that you described. This would
be especially true during a wet year, in soils with high organic matter
or where mulch was present around the crop. These sneaky critters show
up mostly during the evening hours to do their dirty work and then return
to their hiding place at dawn. If the damage was by rodents, I'm sure
there would be other evidence, along with more extensive visible damage.
If the problem begins showing next year, send a sample to me for a more
accurate diagnosis.
Q: We have a very
large Norway spruce in our front yard. We have a tarred driveway that
covers a lot of the area around the base of the tree, so there is not
a big area where we can water the root system. The tarred street also
cuts off the fertilizer supply. For the first time, some of the needles
are falling off the tree. If we had not collected the needles on occasion,
they would have completely covered the driveway and small area of lawn
under the tree. There does not seem to be any sign of disease and we really
haven't tried to fertilize the tree. (Richfield, Minn.)
A: Whatever this
is, it doesn't sound good! Since you live near the Twin Cities, I suggest
looking in your phone book or go to www.isa-arbor.com/home.aspx
to locate a certified International Society of Arboriculture arborist
to examine your tree. It sounds like a needle cast disease, which can
be controlled by timely spraying. Try to get the arborist as soon as
possible to make the diagnosis and set up a spraying schedule, if that
is the problem. Be sure to check credentials and references.
Q: I want to plant
a few new apple varieties out at the family farm this spring. The local
Extension Service agent has recommended Haralson, Sweet Sixteen and possibly
Honeycrisp, but what has intrigued my imagination are two older varieties,
the Wolf River because of its size and the Duchess of Oldenburg because
of its reputed hardiness. However, the Extension Service agents in two
counties can’t give me much information about these two varieties.
What can you tell me about their qualities? Also, I have a little extra
protected space at the farm and I am inclined to plant a couple of mulberry
trees for the heck of it. I have observed that one species of mulberry
grows like a weed in Minneapolis. Does any type of mulberry grow well
in central McLean county? What are their cultural requirements? (Turtle
Lake, N.D.)
A: I’ll answer
your last question first. Forget about growing mulberry trees because
they are not hardy and even if they were, you very likely would not
want them because they are very disease prone and one of the messiest
trees on earth! The Wolf River apple cultivar is of unknown parentage
and was discovered in Wisconsin about 1881. It is the largest apple
grown in that state. The skin is pale yellow, mottled and blushed with
pink to red color. It is best known as a cooking apple and is considered
prime for use as dried apple slices or apple butter. In Wisconsin, the
fruit is harvested between Sept. 25 and Oct. 5. The Duchess of Oldenburg
is a Russian apple that was imported to America from England about 1835.
It ripens very early in August or September and does not store well.
The skin is a pale yellow, striped with red. The flesh is tart and crisp,
which makes it suitable for pies and sauces. It is intermediate in resistance
to cedar-apple rust. The red Duchess is a color strain with similar
characteristics. The source of my information on apples comes from “Growing
Fruit in the upper Midwest” by Don Gordon, UMN Press, 1991.
Q: I am having a difficult
time planting lemon trees. I have taken the seeds and put them in containers
filled with warm water to help with germination. After less than 24 hours,
I took the seeds out of the water containers and then scattered and buried
the seeds into a rich, dark soil. It has been a little less than a month
and still no sign of growth. (e-mail reference)
A: It could be the
fruit was irradiated to slow spoilage or that the fruit was harvested
when it was immature, so the seeds will not germinate. Normally, citrus
seed is quick to germinate. You should see results in a few days to
two weeks. You might want to check with the source to see if the fruits
were irradiated anywhere along the way from harvest to retail sale.
Q: I collected seed
from my petunias last year in hopes of having more plants this year. I
don't think the petunias are hybrids, but I am not sure. I've started
the seeds, which are growing nicely. Is there a way to know what the flowers
will look like? What can I expect to see? (e-mail reference)
A: At least 99.44
percent of the petunias sold on the market are hybrids. Collecting the
seed and sowing it from hybrids is going to give you a "Fibber
McGee's Closet" of plant types and color combinations. They may
not be rewardingly attractive, but it will be a good object lesson in
Gregor Mendel's work with hybrids.
Q: I have a cottonwood
I planted from a cutting a couple of years ago. The original planting
was damaged and I soon had two thick branches growing instead of one main
trunk. The tree splits about 2 feet off the ground. Can I cut off one
of the branches or is there a way to do this in stages that would be better?
(e-mail reference)
A: You can and should
remove the branch; otherwise it will be a source of further problems.
Totally remove the branch so the wound will have a chance to start healing.
Q: We are about to
cut down an old and dying boxelder tree. The big branches that have come
down were rotten and falling apart. Can you burn rotten boxelder wood?
Is it worth trying to keep some of the less rotten parts of the tree to
burn or should we avoid it? (e-mail reference)
A: Go ahead and
burn all of the tree, unless you are fussy about what goes into your
fireplace or storage rack. I can't think of a reason to avoid it.
Q: What is the difference
between a yam and a sweet potato? While I was growing up, we always had
a sweet potato vine. We put it in water and let it grow. Now all I can
find in the grocery store are yams. I have one in water suspended with
toothpicks, but it is only growing roots. It looks like it has eyes, so
I’m hoping it might do something. Do grocery stores in Fargo or
Moorhead sell sweet potatoes? (New Rockford, N.D.)
A: Yams and sweet
potato questions often come up around Thanksgiving, but not around Valentine's
Day! There is a big difference between the two. Supermarket outlets
sell sweet potatoes 98 percent of the time. To end any further controversy
(hopefully!), what the supermarkets are calling "yams" are,
in most cases, sweet potatoes. Why? Because they have the taste most
Americans want and are used to, as well as the texture of the flesh.
Sweet potatoes are grown in the U.S., mostly in the South. Yams are
imported from the tropical regions. Frankly, most of us would find the
yam an unappealing object to gag down without a lot of doctoring first.
It should be no surprise that the sweet potato produces roots because
that is what it is! Even though supermarkets are not using the correct
term, botanically speaking, when they refer to sweet potatoes as yams,
they are forgiven because they are attempting to cash in on our lack
of distinction between the two very different plants! To check out the
differences between these two species, go to www.ces.ncsu.edu/depts/hort/hil/hil-23-a.html.
Q: Is an avocado plant
poisonous to animals? (e-mail reference)
A: The poison principle
apparently depends on the species of avocado. It has been reported as
the source of poisoning in rabbits, cattle, fish and canaries. The Mexicola
avocado did not have the same results. To be on the safe side, assume
the one growing in your house is poisonous.
Q: I think I have
a rex begonia. It has large, colorful leaves and no flowers. It seems
to be doing well except that recently two or three of the leaves became
bleached. All the other leaves look healthy. It has a southwestern exposure.
(e-mail reference)
A: The southwestern
exposure could be the problem because the plant is getting too much
direct sunlight. Try moving the plant to one side or the other to avoid
direct sunlight. It won't cure the affected leaves, but should keep
other leaves from being damaged.
Q: I have two lilac
trees. I need to move them because the garage is being expanded. What
is the best way to dig them up? Do I cut the branches down to the ground
and then dig them up or do I trim off the big branches. My husband wants
to dig around them and then use a rope to pull them out. I don't think
this a good idea, but I need suggestions to convince him not to fire up
the truck. Help! (e-mail reference)
A: The technique
intended by your husband will just about insure the trees won’t
survive. The best way to move them, from the lilac's point of view,
is to have them surgically dug out with a tree spade. The operator can
come in with a small spade and make about a 36-inch rootball. The operator
can move an entire tree in a matter of minutes with a very high chance
the tree will survive. Some selective pruning will be needed. Take out
the oldest canes back to ground level.
The next best idea
is to dig a trench around the plants to make a 36-inch rootball. With
a sharpshooter spade, cut the fleshy roots as cleanly as possible. Having
the new planting holes already dug is strongly encouraged. With a burlap
cloth worked under the roots, slide or tote the plants to the new site.
Be sure the trees are planted at the same depth as before. Drop the
tree into the hole with the burlap because the burlap will rot. Prune
the same as with the tree spade and then water. The popular technique
of a chain around the base and attached to the bumper hitch will result
in a lot of damage to the turf and the plants being yanked out of the
ground. If that is the only acceptable alternative, you might as well
write them off and plant new ones.
Q: I thought you might
be able to help me with a little spruce seedling I am starting in an indoor
pot. I planted it in vermicompost. The spruce did well at first, producing
some new growth. Then the new growth wilted and dropped off. I've just
started to see some needle drop and browning of the needles. The pot is
one of those you put water in the bottom and it soaks up through the soil
as needed. The plant is in a north-facing window. Do you think this could
be related to overwatering, lack of room for the roots or has the tree
used all the nutrients in the compost? (e-mail reference)
A: Spruce seedlings
do not make good indoor plants. They are a temperate zone plant, which
means they need to experience the vagaries of Mother Nature, not the
artificially heated environment that is maintained at a constant 70
degrees with low humidity. The plant is probably a lost cause. The vermicompost
is a good idea, but should be used in seedling beds outdoors. Vermicompost
allows the seedlings to germinate when conditions are favorable and
to "toughen up" to local weather conditions.
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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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