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December
7, 2006
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: Six months ago,
I was at a coffee shop and was admiring the large jade plant they had
near the counter. They said I could take a clipping, which I did. It has
been growing very well and I have become quite fond of it. How long will
a jade plant live? Since I received a clipping from an old plant, will
my jade plant not live as long as one that is started by seed? (e-mail
reference)
A: Don't worry.
With proper care, such as what you obviously are giving your plant,
you will be able to bequeath it in your will to your children. Disease,
insects and improper care, not age, are what kill plants. Enjoy!
Q: I work with children
ages birth to 6. One of our caregivers had the children plant pumpkin
seeds to see if they would grow. The children have cared for them intensely
and the seeds are growing! Since these are young children, we have to
be concerned about ingestion. I’m talking about the vines and leaves,
not the pumpkins or seeds. I know that many vegetable plants are poisonous.
Can you tell me if a pumpkin plant is poisonous? (e-mail reference)
A: Pumpkin vines
are not poisonous. However, being members of the cucumber family, plants
could accumulate toxic levels of nitrate in their foliage if the nitrogen
level is excessively high during growth. Don't overfertilize because
it isn't good for the plant. To get the pumpkin plant to set fruit,
it will have to flower. Usually, the first flowers are male, followed
by the female flowers. They are easily distinguished, so what you and
the children will have to do is wait for the pollen to mature on the
male flowers. You can test it by touching the end of the pollinator,
which is the pistil. The pistil will leave a yellow residue on your
finger. Take the male flower and dust the pollen on the end of the stigma,
which is the female part. Do this several times. When the female flower
begins to discolor and wilt, the pollination and fertilization is complete,
so a new pumpkin will begin forming behind where the petals were attached.
Enjoy!
Q: I'm wondering what
types of trees I should be planting. I have land in northern Bottineau
County that is very sandy. The area where I've tried to get trees started
has some low spots. These areas don't seem to grow vegetation as well
as the higher and drier areas. I’ve had fairly good luck with caragana
plants. The Soil Conservation District did the planting. It mixed some
Colorado blue spruce with other spruce trees in one row. These trees are
four or more years old, but not very tall. I have maintained the space
between the rows fairly weed-free. The trees haven't done as well as I
had hoped. I have watched closely for worms and other insects. I planted
a row of poplar trees in the same vicinity. They didn't do well at all.
I then planted poplars, but they haven't fared any better. As a last resort,
I planted Russian olives. Do you have any recommendations or other types
of trees I might try? I'd like a good shelter strip in as short of time
as possible. (e-mail reference)
A: I'm surprised
that the Soil Conservation District has not offered a wider selection
for your location. Those folks are very regionally knowledgeable about
plant selections. You might inquire about boxelders, silver maples,
catalpa and native bur oak. The redstem, white and golden willows also
are very adaptive trees to the situation you describe.
Q: We have a sloped
area in our yard. We’re looking for a flowering, low-growing ground
cover. It’s in a sunny area and has good soil. What do you recommend?
Also, we have a lot of crabgrass and quackgrass. What would you recommend
to control it and when to apply it in the spring? We enjoy reading Hortiscope.
(Browns Valley, Minn.)
A: Thank you, I’m
glad you enjoy the column! Quackgrass is going to be difficult to control,
but give it a try. Next spring before you plant, spray the quackgrass
with Roundup when it is 3 to 4 inches tall. That will at least slow
it down. Chokeberry, bird's foot trefoil, moneywort and lily of the
valley are some plants you may want to consider. Thank you for your
interest!
Q: My mom had three
Christmas cacti. They used to be different colors, but now they are all
white. Why did this happen and is there a way to make them colorful again?
(e-mail reference)
A: You are asking
a very good question! If you had said that one plant was changing color,
I would attribute that to possibly a genetic material break, but not
with all three plants doing the same thing! It must have something to
do with the environment or cultural practices. I am sorry, but I can't
give you a solid reason at this time. Perhaps some column readers can
provide an answer.
Q: I have several
indoor jade plants that I cherish. They developed white spider webs underneath
their leaves. I sprayed the plant with something organic. Unfortunately,
my husband threw away the can, so I can’t tell you what the product
was. Now the plants have white mildew on their leaves and getting black
spots in the middle. It also looks as if the skin is peeling off. I thought
they would recover, but right now they are doing worse! I thought of throwing
them out because I am afraid that all our plants will become infected.
I know this is not a lot of information, but maybe you have an idea. (e-mail
reference)
A: You have two
problems. Your plants have a spider mite infestation and the other sounds
like powdery mildew. These problems come about as a result of the air
being too dry (spider mites) and possibly the light being too low (mildew).
If the plants are not too far gone, I suggest purchasing some Schultz's
Fungicide 3. This product is a miticide, fungicide and insecticide all
in one. Move the plants to an area with more light or provide artificial
light. Mist the plants with distilled water during the stressful winter
months. Mist the plants about three times a week. If they don't begin
responding favorably almost immediately, then dump the plants and start
again. In the meantime, keep some distance between them and the rest
of your houseplants.
Q: I'm doing a project
on phytophthora infestations in potatoes. Do you know what the chemical
equation is for the mold to occur? I know the fungus thrives in 75 percent
to 100 percent humidity and needs mild temperatures. I need to know the
chemical equation of how this occurs in potatoes on the molecular level.
Also, do you know what happens if someone eats the fungus? There has to
be a reason why not to eat infected potatoes because a lot of people starved
to death in Ireland. (e-mail reference)
A: Thanks for your
question! I'm forwarding it to our undeniable NDSU potato expert at
all levels (breeding to cooking), Susie Thompson. She will get back
to you with a solid answer that should get you an "A" on your
project. I'm glad to see your interest in this subject. Have you read
"Famine on the Wind?” It was one of my favorite readings
when I was taking a plant pathology course in college. It is out of
print, but I'm sure your school or public library would have a copy.
Reading it could help flesh out your project with some good background
information.
The following is
an answer supplied to the reader by Susie Thompson.
A: Thank you for
the question and having an interest in potatoes. I am unaware of a chemical
equation relating to the infection or invasion of potatoes by phytophthora.
Let me tell you a little about the Irish potato famine and the newer
strains of late-blight. The Irish potato famine happened because the
potatoes rotted, often right in the field. Additionally, the foliage
(plant canopy) would have been impacted first. Therefore, the tubers
may not have formed because of the vine’s premature death. At
that time in history, many Irish peasants lived on potatoes and milk
supplemented with other foods, but these staples provided all the necessary
amino acids for human health. Also, some of the harvested tubers may
have broken down (rotted) while in storage, again reducing the food
supply. To my knowledge, there is no toxin produced by late- blight
fungus that would cause harm to humans. That is not the case with some
other crop pathogens, such as headblight in wheat that produces an aflotoxin
or ergot in many small grains. The genotypes of the late-blight fungus
changed between the 1840s and the early 1990s, when late-blight again
reared its ugly head. The new biotypes are much more aggressive and
virulent, attack different parts of the canopy and rapidly grow on tubers
and foliage, even at high temperatures. In foliage, the optimum temperature
is 59 to 68 degrees, but it can grow at
much higher temperatures. For example, temperatures into the 80s under
high humidity (75 percent to 100 percent). The optimal temperature for
hyphal growth and development in tubers is 50 degrees. The lower limit
for growth has not been determined. The base temperature of this obligate
parasite may be related to that for potato leaf and sprout development,
which is 39 degrees. I hope this helps some. A good article was in the
Valley Potato Grower magazine about 20 years ago (sometime between 1985
and 1989, if I recall). It was written by Phil Nolte and may have been
in two parts. Best wishes on your project.
Q: I have a very large,
old weeping willow tree near my house. A lot of big roots have surfaced
in the lawn. To keep from breaking the mower blades, I decided to mulch
over the roots and build the soil to plant other things around the base
of the tree. However, someone told me that mulching the exposed roots
would kill the tree and it could fall on my house. I can't believe this
is true, but it could be. If not, do you have any suggestions on what
would be good things to plant under the tree? Do I need to remove the
mulch? (e-mail reference)
A: Some soil and
mulch over the roots of a willow tree will not hurt the tree unless
you use excessive mulch. I suggest a sandy loam with ample organic matter
added, such as peat moss. Do not cover more than 6 inches of the roots.
Do not go against the tree's trunk. Leave about 6 to 8 inches clear
of any soil or mulch covering the trunk.
When topsoil is dumped to a depth of 18 to 24 inches and up against
the trunk is when problems develop that could threaten the safety of
the tree.
Q: I have a Christmas
cactus that turned brown, but you can see green under the brown. The plant
is growing, but it has not bloomed since I got it. I have repotted the
plant and given it some Miracle-Gro. What am I doing wrong? (e-mail reference)
A: I cannot determine
what you are doing wrong based on what you have told me. Christmas cactus
is a fairly easy houseplant to grow. If you are guilty of anything,
it is probably giving the plant too much water. Go to my Web site at
www.ext.nodak.edu/extnews/hortiscope/houseplnts/xmascctus.htm.
The Web site has dozens of questions and answers on this plant species.
Q: I have a spruce
tree that I took home from kindergarten on Arbor Day in 1971. It grew
into a beautiful tree at my parents’ house, but had to be cut several
times because it was growing into telephone and power lines. I have the
sad task of cutting the tree down. I want to save the cones and maybe
cuttings to try to create a new tree or trees. Can you tell me how to
do it or refer me to someone who can? (e-mail reference)
A: That is some
treasure to have to lose. Unfortunately, the cones already have dispersed
their seed or have been consumed by wildlife. Growing spruce using cuttings
is not easy, even for professional growers. For a good keepsake, I might
suggest taking some branches and having them plasticized for preservation.
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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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