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November
3, 2005
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: I have a fairy rose that appears healthy and produces many buds, but
will not produce flowers. What do you think is the problem? (e-mail reference)
A: It could be thrips or aphids feeding at the base of the buds or
within the fold of the buds that keep the flowers from opening. Check
the flowers closely. I’ll bet you will find evidence of one or
the other.
Q: I am wondering if you could help me with my apple tree. My Hazen tree
has been producing for about seven years, including more than 200 hundred
apples each of the last two years. This year, the tree blossomed, but
only two apples grew. It looks healthy. Any ideas would be helpful. (e-mail
reference)
A: Cold, windy and rainy weather at the time of flowering could be
the problem. This inhibits the pollinating insects from doing their
job or the tree has simply “exhausted itself” trying to
please you with abundant fruit. Be patient, next year the fruit likely
will return by the bushel.
Q: I have had a problem with raccoons all summer. They ate some things
in my garden (which is fenced), but then moved on to my garage to clean
out the cat food every night. We have outside cats that go away for days
at a time, so I like to leave food out for them, but the raccoons have
quite an appetite! Does anything short of lead poisoning work for raccoons?
I did find that planting zucchini, pumpkins and squash around my sweet
corn did well at keeping the raccoons away from the corn. They must not
like prickly vines. (Kindred, N.D.)
A: Zucchini keeping raccoons at bay? That is possibly the best use
I have heard of for zucchini!
I was going to suggest “Liquid Fence” because it smells
gross. I imagine it also tastes bad, but I don’t know if it tastes
bad enough to keep raccoons away. You might try live trapping the raccoons
to see if that works, but I think they’re too smart to fall for
that! Thanks for the tip. I might write a grant proposal to see if,
under controlled conditions, the zucchini plantings actually keep the
coons away! In your case, it might be that they were just full of cat
food, so corn on top of that lost its appeal!
Q: This year I was looking forward to the blooms that I thought would
come out on my Madame hardy rosebush. The buds were plentiful, but they
wilted, went yellow and fell off. Please help. (e-mail reference)
A: Look for cane borer, thrips or cane girdler damage. If the rest
of the plant is healthy, it has to be an insect-caused problem.
Q: We inherited a robust grape vine (we think it is a Concord) when we
bought this house 12 years ago. Each year we pick the ripe grapes and
make grape juice (adding organic apple juice to sweeten it). Someone suggested
we cut back the leaves so the grapes get more sun and are sweeter. Would
you recommend this very labor-intensive approach? The vines have never
been pruned to our knowledge, but don’t seem to get bigger. Should
we leave the vines the way they are or start pruning now? (e-mail reference)
A: Sun-ripened grapes will have higher sugar content than those grown
in the shade of the leaves. However, why change if you are happy with
the process you are going through and not inclined to get into pruning?
Q: I have an indoor plant that I was told is a corn plant when it was
given to me. However, it doesn’t look like the pictures that I have
seen of corn plants. My plant has leaves like a corn plant that would
grow in a field and are a solid, dark green color. Recently, when it was
moved into my house, some of the leaves turned black and began curling.
They don’t appear to be dying, but are curling under and not staying
wide. I have no idea what the problem is. I can’t find the proper
care because I can’t find the proper name of the plant to match
what it looks like. (e-mail reference)
A: The corn plant is known botanically as Dracaena species, of which
there are many! Most people go for the exotic types, such as a variegated
species. Yours is the unvariegated form. Go to the following Web site
to see a form that resembles yours: www.desert-tropicals.com/Plants/Agavaceae/Dracaena_fragrans.html.
Then go to www.ext.nodak.edu/extpubs/plantsci/landscap/h1260.pdf
for complete information on the care of houseplants.
Q: We have an organic garden with an earwig problem. I’m told a
mixture of water and soap can be sprayed on plants that will kill earwigs,
but not plants. What mixture should I use? Do you have any other suggestions?
(e-mail reference)
A: Don’t try it! Purchase some insecticidal soap and use that
instead. It is formulated to not damage plant material. You might be
lucky one time and unlucky another because the fatty acid chain changes
with each new batch of material produced. Besides, you need to hit the
insect directly to be effective with this material. Earwigs do very
little damage to plants. As an organic gardener, I’m a little
surprised that you don’t know that their major source of food
is other insects, especially aphids. You can trap and dispose of them
by rolling up moistened newspapers if you consider them a pest, which
they can be if they get into your home!
Q: My mother-in-law who is 88 loves trees and has a lovely cutleaf birch.
Is there a difference between a cutleaf and a cutleaf weeping birch? She
says hers is just a cutleaf. She also is wondering if there is any way
you can start a new tree from seed. Thanks for you help! (Wolford, N.D.)
A: There are cutleaf weeping birch trees and semiweeping birch that
have the cutleaf foliage.
Birches can be started from seed, but the character is liable to be
lost. Normally, nurseries will graft these beautiful plants because
the cutting success is only 25 percent or less with great effort.
Q: I have had a hydrangea for about three years, but I’m not sure
what kind it is. The bush is healthy, but it seems to me that only part
of the flower head blooms. Maybe six or seven flowers and the rest seem
to remain closed. The expert at the local nursery says that it is a lacecap
and that is what it does. If this is the case, I certainly got the wrong
kind for what I want. What do you think? (e-mail reference)
A: That is exactly what lacecaps do. They have a center of fertile,
nonshowy flowers and an outer ring of showy, nonfertile flowers, which
provides a nice pinwheel effect that many people like. Apparently, you
are not one of them. You probably would like the all-sterile flowers
found in hortensias. Dig the present one out and get what you want in
a plant. Life is too short to put up with something that falls short
of expectations!
Q: For several years, our property was a local park and then sat empty.
When we bought it, we were told that the original town included a hotel,
blacksmith shop or stable that were located on the property. That late
summer when we asked about a stretch of grass that appeared to be dying,
we were told that many years ago a sidewalk was located across the front
of our property. We were told that the concrete was broken up so it shouldn’t
be a problem, especially if we hauled in black dirt. We’ve done
the repeatedly, but every year the “sidewalk” kills our grass.
This year we dug out a portion of that area and discovered much of the
sidewalk was nearly intact. It was a grueling task taking it out and we’re
not done yet. Is there any type of grass seed that has short roots or
can survive (thrive?) in 4 to 6 inches of soil? We had to quit with 30
or 40 feet of sidewalk remaining buried in our yard at varying depths.
My husband is willing to try seeding one more time, but we don’t
want to waste time and money. Please help! (Buchanan, N.D.)
A: In a “perfect world,” the sidewalk would have been jackhammered
and hauled away, but life is not perfect and neither are the things
that people do. The O.M. Scotts Co., about 35 years ago, proved that
grass could be maintained on concrete. It brought in a concrete truck
and had the entire turf area around this poor individual’s home
covered with 4 inches of concrete and then laid sod over it. Through
a strict regime of watering, fertilizing and mowing, they maintained
that turf for several years. I have no idea what the input costs turned
out to be, but I would imagine that it was substantial. In your situation,
you likely always will have a problem with this “streak of concrete.”
It will dry faster and therefore be subject to heat and drought stress
quicker than the surrounding turf area. You might check on the cost
of having the remaining concrete removed because it may help save your
sanity. I would suggest using one of the fine fescue cultivars, such
as Cindy, Dawson or Navigator. These are drought-hardy grasses and may,
with a little coaxing, make it through the summer heat without dying.
It's too bad that one of the buildings on your property wasn’t
a bank because it might have lost some dollars for you to find!
Q: Our blue spruce trees have multiple small, orange dots on their needles.
When handled, the orange dots seem to be quite powdery. What is this?
What should we do? (Hibbing, Minn.)
A: This is a rust fungus, but you need a lab analysis to determine
which species of rust. You can send a sample to the University of Minnesota
plant diagnostic clinic or to NDSU’s plant diagnostic lab for
analysis. There is a nominal lab fee in both cases. Identification is
important so that the alternate host can be determined and possibly
removed. In the meantime, I would suggest a protective spray of Ferbam
or a sulfur-containing fungicide, such as Bordeaux mixture.
Q: I have two hedera ivy plants in a west window that seem to be doing
well. Not being terribly educated in the area of houseplants, I fear I
mistakenly repotted them in pots that are too large. However, they are
doing well. After reading your question-and-answer section on ivy plants,
I was unable to find an answer to my two questions. How do you “cut
back hard” ivy plants? The vines on my plants reach lengths up to
3 feet. Is there a particular way they can be lifted up so that they don’t
look scraggily? These are the first ivy plants that I’ve had some
success at growing in the 25 years of having houseplants, so I don’t
want to mess it up. (e-mail reference)
A: You shouldn’t worry because hedera ivy is a difficult plant
to mess up! Pruning or “cutting back hard” simply means
reducing the size of the plant significantly. In your case, it would
mean reducing the plant from a straggly 3 feet to about 12 inches. In
doing that, you are encouraging the plant to send out more new growth,
which will help it become a more “bushy” vine (an oxymoron,
really). The one thing you need to be careful about when repotting into
a larger pot is overwatering. English ivies do not need a lot of water,
so when you think they need water, think again and water at least a
day later.
Q: I have a Concord grapevine in my garden. The grapes are turning brown
on the vine and a few of the leaves have red dots. Any idea of what I
can do? (e-mail reference)
A: The fruit symptoms sound like botrytis fungus and the leaf symptoms
resemble a fungal disease known as black rot, but only a lab analysis
can confirm these guesses. Fungicidal sprays, such as Captan, will control
further spread, but will not cure what already has taken place. Keep
in mind that some fungicides should not be used, such as the sulfur-based
types, when the temperature is 85 degrees or higher. Be sure to read
the label directions. Both of these maladies show up during rainy periods
and times of high humidity. Proper pruning, good air circulation, avoiding
water splash during irrigation and preventative applications of fungicides
will control these diseases.
Q: My bleeding heart is done for the season. It sure looks ugly now.
Should I cut off the dead stems and dry leaves? If I do, will it come
back fuller next year? (e-mail reference)
A: Yes, this is characteristic of bleeding heart. Once they flower,
they begin a decline in appearance and die out once their cycle is complete.
The crown now has stored enough carbohydrates to come back next spring
with an even more attractive show of flowers and foliage.
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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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