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September
14, 2006
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: My bleeding heart
is turning yellow and getting smaller. It was planted last summer and
looked good until this year’s extreme heat. (Moorhead, Minn.)
A: Bleeding heart
plants die back slowly after they are finished blooming. Let nature
take its course. Your plant died back at an accelerated rate this year
because of the extreme heat and drought. The plant should be OK.
Q: I have a dieffenbachia
plant that has some yellow growth coming out of the soil. I took a spoon
and dug it out. The growth appears to only be on the surface. Any idea
as to what it could be? (e-mail reference)
A: Nothing to worry
about because it is a harmless saprophyte growing on the organic matter
in the soil. Usually, it is just nondefined growth that easily can be
spooned away the way you did.
Q: We are considering
planting a privacy screen between our lot and the neighbor’s. We
have a sizeable lot. Can you give us some ideas on what trees to plant?
We have no height restrictions where we live. We want trees that are disease
resistant, hardy and do not send up suckers. (Lisbon, N.D.)
A: This is something
that you will have to do. All I can do is give you guidelines, which
can be found at www.ext.nodak.edu/extnews/askext/treeshr/1411.htm.
Then go to www.ext.nodak.edu/extnews/hortiscope/tree/treecntnts.htm
for a listing of tree species. Click on a species name for more information.
That way you will be able to make educated decisions about what it is
you can plant, but are not limited to my biases or preferences. Everybody
views trees and privacy screens differently, so it is a personal choice.
Two of the most notorious species for suckering are cottonwood and cherry
or plum. The Cass County Extension horticulturist has a very nice listing
of trees with photos at www.ext.nodak.edu/county/cass/horticulture/treeshrub/decidtrees.htm.
Q: We had a person
call today inquiring about growing grapes in North Dakota. He has valiant
grape plants hardy for zones 3 to 8. After he pruned his plants, he planted
the cuttings in pots.
What does he do with
the cuttings for the winter? (e-mail reference)
A: Assuming they
have rooted in the containers, when fall comes and the leaves drop,
have him plant them where he wants them to grow and water them well.
They will survive, unless we have a record-breaking low temperature,
with little to no snow. If he doesn't want to take them out of the pots
because they will be planted elsewhere or given to someone, have him
put the plant, pot and all, into the ground and water in. The following
spring he can lift them out and give them away or plant them where he
desires.
Q: I bought a new
house in West Fargo three years ago. The first year, I sprayed the yard
twice with Roundup to kill the weeds. The next spring, I had problems
with the sprinkler system that I had installed, so the weeds grew again.
I resprayed with Roundup. In late July, I leveled the yard, planted a
quality grass seed and started growing a lawn. I have been spraying the
quack grass for two years, but this year is the worst. I have more of
the weed than I had the last two years. I water the lawn four times per
week and fertilize. Last spring, I applied Scott’s Turf Builder
with "halt," but I am still losing the battle. Do you have any
suggestions short of killing the entire lawn and starting over? (e-mail
reference)
A: I'm sorry to
tell you that it is a losing battle. I know from experience. I have
killed my lawn three times in the past 21 years. Each time I thought
the quack grass was eliminated. One year I even "teased" it
to sprout by watering my dead grass to see if anything would come up
prior to overseeding. It did, so I sprayed the blasted grass again.
For about a year or two after that, it appeared that I had finally won
the battle, only to see it come creeping back again. I have now resigned
myself to living with it, mowing high, fertilizing and watering on a
regular basis. If you don't look closely, the lawn doesn't look too
bad. What I have learned about this persistent grass is that the rhizomes
have latent buds that become activated when the terminal buds or leaves
are killed. About two weeks or so after killing off the leaves, the
dormant buds begin growing. I could go on and on about our battling
this pesky weed. If you are going to launch another attack on your lawn,
now is the best time to do it because of the higher rate of translocation
to the roots and rhizomes. Allow the grass to grow long and then apply
a herbicide. When everything appears dead in a week or so, scalp mow
and collect the clippings. Then lightly power rake, overseed and water.
You just might get a leg up on the quack grass and enjoy a summer or
two of it at least not being noticeable.
Q: When is the best
time of the year to plant new potentilla bushes? (Fargo, N.D.)
A: Anytime you have
a plant handy, the ground isn't frozen and you have water available
to get it established. In other words, now would work for a container
plant and so would later in the fall or next spring.
Q: I've had a braided
ficus tree for about 15 years that has done well. This past week I noticed
it was growing fruit. Is this normal? Is the fruit poisonous to pets or
children? Thanks in advance for any information you can provide. (e-mail
reference)
A: It is not normal
on a houseplant, but it is not poisonous. However, it is not a good
idea to allow children or pets to nibble on the fruit because it may
cause tummy aches or other problems. If you are concerned, I'd suggest
picking the fruit as it develops.
Q: We have a lovely
north star cherry tree loaded with fruit that we would like to harvest.
How can I tell when the fruit is ready to pick? We live in Bismarck, which
is the land of drought and heat. (e-mail reference)
A: The fruit should
be ready to harvest by now with all the heat we've had. However, no
matter how long you leave the fruit on the tree, the fruit will be sour.
It should make excellent jelly or convert nicely into wine.
Q: We have a lilac
tree that just started to grow and bloom this year, but it seems we have
carpenter ants in the tree. The ants have cut a groove into the base of
the tree. I would love to get rid of them before they destroy our beloved
tree. It appears that the tree is extruding sap. Could this be why the
ants are attacking the tree? It also seems we have attracted yellowjackets.
Any suggestions? (e-mail reference)
A: It sounds like
you have borers causing the sap to flow from the branches. You also
may have an aphid infestation that is causing the sappy dripping. Ants
will use the aphids in the same way we use cows for milking, except
the ants collect the honeydew the aphids excrete through their bodies
as a result of their feeding. This same material interests the yellowjackets.
Examine the plant to see if aphids or any other insect that has a piercing-sucking
mouth part, such as scale, are present on the stems and leaves. Examine
the stems as well to see if there are specific sites where the sap is
being exuded. This would indicate the possible presence of a lilac borer.
If you don't have the confidence to make these judgments, contact a
tree, shrub or landscape service to do it for you. It would be a good
idea to control the yellowjackets using traps rather than sprays. Their
stings not only hurt, but can be toxic to certain individuals.
Q: My honey locust
is looking somewhat sick. It was covered with heavy ice for several months
last winter. Right now, it looks spindly and has more pronounced leaves
at the ends of the branches. I have deep-watered it several times this
summer, but I am sure it was not overwatered. Will it recover? (Kent,
Minn.)
A: From your description,
I doubt it. Consider replacing it this autumn with a more robust tree.
Q: What are the red
egg clusters on the underside of my silver maple leaves? (West Fargo,
N.D.)
A: The red blisters
you are seeing is a reaction to eriophyid mites feeding and laying eggs
in the early spring as the leaves unfold. What you are seeing is a cellular
reaction to this activity. It is not detrimental to the growth or health
of the tree. Any spray activity now would be futile in controlling or
eliminating the mites. By next year, they may be gone anyway if controlled
by natural predators.
Q: What is the best
way to plant a cutting from a seedless cottonwood? (e-mail reference)
A: Depending on
the tree's vigor from which the cutting was taken, root it during August
under an intermittent mist system or mist frequently every day. Plant
the cutting in a sand/peat mixture under partial shade. Dipping the
cutting end in a rooting hormone prior to sticking it in the ground
will improve its rooting time.
Q: Can Virginia creeper
be grown on brick without damaging it? (e-mail reference)
A: It can be grown
on good or new brick facades. However, think carefully before doing
this. Think ahead 10 to 20 years to see what the result will be. If
you don't like it or it attracts too many birds and/or insects to your
liking, it is a pain to get it removed.
Q: I purchased a PJM
rhododendron, a northern lights variety of azaleas and an endless summer
hydrangea. I lost them all to root rot by overwatering. Imagine overwatering
in South Dakota, which is having the worst drought in the last 25 years.
Can these same varieties be planted in the same location next spring?
I'm concerned with bacterial spores remaining in the soil/peat mix. Thank
you for your expertise, you offer a great deal to our gardening society.
Bless you. (Mt. Vernon, S.D.)
A: Thank you. I’m
glad the information is useful! To be on the safe side, I would remove
the soil and replace it with dirt from another location. It would be
frustrating to replant and have the same thing happen again! From a
plant pathology standpoint, it is never a good idea to replant in the
same location with the same species of plants.
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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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