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December
29, 2005
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: I have a question
about Juneberry shrub trees. When the Juneberries start to ripen, they
get red in color and then something starts to grow on them, almost like
a fungus. What could it be and what can be done? (e-mail reference)
A: It is a fungus,
most likely cedar-apple rust. Juneberry is in the same family as the
apple (rose), so it is subject to some of the same diseases. The easiest
way to control this is to find the offending juniper and remove it or
pick off and destroy the orange, golf ball-sized fruit that is present
before sporogenesis has a chance to begin.
Q: I have a heart
hoya that I received a couple of months ago. It was a single branch about
a foot long and leaning out of the pot horizontally, with several mature
leaves and a flower stem. It sits in a south window and gets lots of indirect
sunlight. Shortly after I got it, it started growing a new branch straight
up from the horizontal piece. The new branch is at least 2 feet tall,
with new leaves, flower stems and new growth nodes. Should I cut the top
to force it to grow in new directions or let it continue to grow? (e-mail
reference)
A: The plant apparently
is in a strong vegetative stage of growth. Cutting it back to a node
would help force it to branch more and eventually flower. You must have
some very good potting soil to be getting that kind of response.
Q: This spring I purchased
a hibiscus plant. I repotted it into a little larger pot and set it on
the south side of my house. It grew and bloomed beautifully. Since I would
like to keep it for next summer, I took it in the house. The plant has
continued to bloom, but when I water it, I get many yellow leaves. What
is the best way to care for this plant to keep it alive? (Grafton, N.D.)
A: What worked for
me is to allow the plant to go dormant with a little help from Mother
Nature. After going dormant, bring it indoors and put it in the garage,
where it will get cold, but not drastically. Store it that way for two
months. After that, bring it indoors, cut it back to the nodes and place
it in a sunny window or under some grow lights. By the time spring arrives,
it will be a beautifully blooming specimen for your outdoor setting!
A word of caution: Use tepid water and do not overwater during the slow
winter months.
Q: We have an amur
maple tree that has quite a few more branches and foliage on one side
and the leader is bending over instead of going straight up. Any suggestions
for pruning or what we can do? (Marion, N.D.)
A: Prune it next
spring before the buds open. The tree will bleed, but that should not
cause any problems, so don't let it bother you. I cannot tell you “how"
to prune it by e-mail because each tree pruning situation is different
and involves both art and science!
Q: My peace lily is
growing rapidly. I repotted it and found it very difficult to break apart
to give to others here at work. Can I cut the roots with a knife? I didn't
want to hurt it. It grows great under the florescent lights and I get
flowers often. I have been reading from your other inquirers about giving
it a rest period. If it is growing so well, why let it rest? (e-mail reference)
A: You can cut it
apart with a knife. You will know when the plant wants a rest period.
It will stop flowering and the foliage will be discolored or pale and
limp. Allow it to die down by withholding water (as happens in its native
setting) almost completely. Allow it to rest for eight to 12 weeks,
barely watering lightly during that time. Often, a bud will appear after
the rest period. When that happens, start watering again. Enjoy!
Q: I saw on the Internet
a few weeks ago that an easy way to eliminate slugs is to spray the affected
areas with a mixture of one part ammonia and two parts water. Will that
mixture affect what is growing or planted later? (Fargo, N.D.)
A: You need to get
the spray on the slugs to be effective. Go to this earth-friendly Web
site at http://eartheasy.com/grow_nat_slug_cntrl.htm
for a list of natural slug controls, including the ammonia/water remedy.
The solution doesn’t harm the site or the plants. Thanks for making
contact!
Q: I am working with
a customer who has lilacs that look more like trees than bushes. The lilacs
are at least 15 feet tall. Is it possible to top the lilacs down to his
fence height or just prune the smaller growth and live with the height?
Is fall the best time to cut and prune? (e-mail reference)
A: Topping will
produce only ugly looking plants that won’t make you happy. Prune
the lilacs in the spring, right after flowering. I would suggest doing
a three-year reduction in size. Take out a third of the volume each
year by cutting the large branches to the base of the plant. That will
keep the plants closer to their natural shape, but with new growth generated
each year and the flowering constant.
Q: I am wondering
about watering my trees, shrubs and evergreens before winter. The ash
trees have lost their leaves, but some of the other trees have not. Is
it OK to give everything a good final watering or do I have to wait until
all the leaves drop off? I have some questions about my shrubs. The snowball
and mock orange still have many leaves. You told me earlier that I could
cut them close to the ground in the fall because they are too large for
their space. My husband does not like to trim, so I want to make sure
this is the time to do it without killing anything for next year. Should
they still be watered before winter? Should I wait for spring to trim
the evergreens? I trimmed them this summer, but did not take enough off.
I always read your column. It is very informative and I am never too old
to learn something new. (e-mail reference)
A: Thanks for being
a loyal reader of the column! Glad it has helped you. You can water
the trees and shrubs before winter weather closes in. Better to get
some water into the cell tissue before that time so there is less chance
of winter desiccation. Wait until spring to prune the deciduous shrubs
and evergreens. It will be better in both instances. You can cut the
flowering shrubs down to the ground to get a reflushing of new growth.
Q: I found some Wilt
Pruf at a local store. On the label is says, "For winter protection:
When spraying on arborvitae, etc., be aware that if these species have
not sufficiently hardened off for the winter, whereby moisture retreats
to the root system, moisture in plant cells could freeze and burst if
early severe freezing weather should occur." What is hardened off?
When do you feel it is safe to apply? Should it be used liberally? (e-mail
reference)
A: Hardening off
is a term used to describe plants that are exposed to the elements coming
into the winter or, as in the case of annual flowers and vegetables,
our "normal" North Dakota spring weather. To be safe, the
plants probably should go through a few more cold snaps and the material
applied on a day when the temperature is 40 degrees or higher and a
Manitoba clipper is on the way in a few days.
Q: Does a healthy
mountain ash that is 25 to 30 feet tall and planted approximately 20 feet
from the house need to be sprayed with Roundup several years in a row
to kill it? I want to protect the foundation. Does this species qualify
as a weed? (Valley City, N.D.)
A: Mountain ash
trees are not weedy or a threat to foundations. It sounds like you have
a beautiful tree, so I would suggest trying to do all you can to preserve
it. Healthy mountain ash trees are an asset to any landscape!
Q: I read your material
on bleeding hearts, but didn't find my problem addressed. I have a bleeding
heart that has grown well, but didn’t bloom this season. When we
purchased it some time ago, it was loaded with blooms. We use Miracle-Gro
when fertilizing. (e-mail reference)
A: Growth with no
blooms usually translates to one of two problems. The plant is not getting
enough light or the nitrogen level in the soil is too high.
Q: If I cut down a
yucca plant this fall, will it come back in the spring? (Mandan, N.D.)
A: It probably will,
assuming it was healthy and that your area isn’t zapped with a
sudden cold snap into the teens! It actually would be better to do it
next spring rather than now, as who can predict what the weather is
going to do?
Q: I have an indoor
China doll that I've had for a couple of years. It has started to get
"cotton-like" spots on the leaves and joints of the branches.
I really don't want to loose it or have it spread to the other plants
in my house. Can you tell me what it is and how to treat it? (e-mail reference)
A: Those cottony
spots could very well be cottony cushion scale. If their numbers are
small, you can swab them off with an insecticidal soap or alcohol-dipped
cotton swab. If the numbers are too high, then you need to turn to a
systemic insecticide, which is potent and has collateral effects on
some plants.
Q: I have a large
willow tree in my back yard. For some reason this year, it is "raining"
sappy, watery, clear-colored drops. It did not do this last year. What
is it, why is it doing this and what can I do to stop it? (e-mail reference)
A: This is from
insects and/or mites feeding on the foliage of the tree. They insert
their stylet-type mouth parts and extract the juice from the foliage.
It passes through their bodies and then is known as honeydew, which
is a euphemism for insect poop! Get someone who knows what he or she
is doing to spray the tree to bring these pests under control.
Q: We have sold our
house in central Minnesota and will be moving around December 1. Can I
dig up our rhubarb, store it for the winter and then transplant it in
the spring at our new house? If so, what is the best way to do this? (e-mail
reference)
A: Yes, you can.
Dig up the rhubarb before the soil freezes in your area. Immediately
wrap the roots/crown in damp, unmilled sphagnum peat moss. Temporarily
set the crown in the soil at the new home and moisten. It is OK if the
planting mass freezes. Replant in its permanent location as soon as
possible next spring. Make sure the area gets full sun and has well-drained
soil.
Q: I feel like an
idiot. Your Web site says to drill a hole in the blossom end of a decorative
gourd to dry it out. Which end is the blossom end? (e-mail reference)
A: The blossom end
is the end opposite the stem. Gourds, pumpkins, tomatoes and even zucchini
squash have stem ends, where the fruit is attached, and blossom ends,
where the fruit developed. It is interesting to observe this happening
on cucumbers or squash because there are separate sexes on the same
plant. The male flowers never develop fruit, so once the pollen is spent,
they simply whither and die. The fertilized female flower has an ovary
or several ovules within that are fertilized by the germinating pollen
tube, which then begin swelling and become the fruit we enjoy. Shortly
after fertilization is complete, the female flower withers and falls
off the fruit 99 percent of the time.
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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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