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Ron Smith answers readers' questions about the world of plants and gardening.

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Some of the leaves on my linden tree are curled and
shrunken. When you peel the leaves, there is a white substance
near where the leaf is attached to the stem. Can you identify
the problem and what can be done to fix it? My next question
is about my apple tree. I think it is being "nailed" by a
woodpecker. It is full of holes that look like they were made
by someone pounding a nail into the tree trunk. They follow
the circumference of the tree in a nice even line. Also, where
I had previously cut a branch off the tree (and sprayed the
area with the black spray paint to seal tree wounds),
something has hollowed out a nice little cave. Is it a
woodpecker that is having its way with my tree? I heard
woodpeckers attack trees when they are infested with bugs. I
lost a pussy willow tree a few years ago. It had the same type
of holes in the trunk that are now on my apple tree. When I
cut the pussy willow down, the trunk had live worms or larva
inside of it. (West Fargo, N.D.)

A: The linden looks like it could be showing the results of
leafhopper damage or herbicide drift from lawn applications to
control dandelions and other broadleaf weeds. The apple tree
is being nailed by yellow-bellied sapsuckers, which are in the
woodpecker family. They are doing it because it is a
smorgasbord of insect larvae for them to feed on. Your apple
tree is likely doomed, but I can say exactly when. As to what
is going to deliver the fatal blow, my bet would be with the
disease problems the tree appears to have. The sapsucker is
doing only what comes naturally.

Q: Do you have any idea what would cause coleus leaves to
dehydrate in the middle? The problem seems to start at the
midrib (both sides) and work toward the edge of the leaves.
The plants appeared healthy at purchase. (e-mail reference)

A: It sounds like it could be botrytis, a fungal disease
brought on by too much water and high humidity. It is not
unusual considering where coleus is planted, such as shaded
locations where sunlight cannot dry the foliage quickly.

Q: Earlier this spring I requested manure for my garden. A
farmer brought me too much manure and it was too fresh. Now my
cabbage plants are not growing and the leaves on my tomato and
peppers are turning yellow. Is there anything I can do for
them? Will they snap out of it and start to improve? Some say
give them lots of water and some say it will be better next
year. What do you say? (Golden Valley, N.D.)

A: I doubt your plants will recover this year no matter how
much water you apply. Give it a year to "weather" somewhat and
next year's crop should be fine.

Q: I read in your column where someone is asking how to keep
deer out of your garden. I have tried a remedy and it seems to
work. You buy a couple of bars of original Dial soap (or you
can break them in half) and put a piece in an old nylon
stocking. Tie them in trees close to the garden. The deer were
tearing off the bark of some young trees with their horns. My
remedy seemed to help a lot. I seldom see any deer in the yard
anymore. (Enderlin, N.D.)

A: Thanks for the tip on deer control. I have heard that it
works for some people, but not for others. Glad it worked for

Q: I think that my grapevine leaves have a disease or
parasites (I see small worms on the leaves). I just moved into
a house with a grape arbor, but I don't know how to take care
of it. It is growing like wildfire, but many leaves have
holes. Some leaves are completely eaten away or destroyed.
What does this mean? Can I save my grapes? (e-mail reference)

A: It means that you have some critter out that is finding
your grape leaves very tasty! Spray the plant with Sevin
insecticide. Be sure to cover all leaf surfaces.

Q: I have several peonies that were here when I bought my
house (19 years ago). I've divided and shared a few times. The
plants are very healthy and always covered with sweet flowers.
I have no complaints. I am curious why, after they've bloomed,
there are always a few flower buds that never open. (e-mail

A: Good question! I could not find the answer in any of my
references, so let's explore some possibilities. Earlier,
heavier blooming depleted the energy to open the last ones. It
could be some sexual parts of the flower are underdeveloped.
It could be a response to the shortening length of sunlight.
That is all of the possibilities I can think of for now.

Q: We have a flowering crabapple tree that shades a large
portion of our house. It was here when we moved in 15 years
ago. It bloomed profusely this spring, but it is already
losing its leaves. What does this indicate? There are several
yellow leaves on the tree that I suspect will soon fall. I
would hate to have it die. What are your suggestions? (Sioux
Falls, S.D.)

A: The tree is obviously subject to a leaf spot (likely scab)
disease problem. It will take a lot more than this to kill the
tree, but it will weaken it and make it vulnerable to other
problems. You can spray with a Funginex or Bordeaux mixture
right now to help prevent the spread of the spores to the
uninfected growth. Clean up all leaf and fruit liter this
fall. Next spring spray the tree with lime-sulfur before
leafing occurs. As they open, spray with the aforementioned
fungicides or Captan.

Q: I plan to go searching the Burleigh County and Rock Hill
Township area for Juneberry bushes to make pies. A friend says
Juneberries aren't ready until the middle or late July. Isn't
she thinking about chokecherries? Can you tell me when
Juneberries ripen? I would think June since they are called
Juneberries. (e-mail reference)

A: Judging from my own Juneberries, I would say that sometime
around the middle of July is about right. Find one growing
locally on someone's property and gauge your visit to the
wilds on that. The season can move a week or two based on
weather conditions.

Q: Last year one of my miniature barberry bushes suffered
about 90 percent winterkill and another about 60 percent. We
replaced one and are waiting on the other to see if it turns
out looking better than it does right now. Can I prune away
the dead limbs? Will it eventually fill in with new limbs?
Should I have mounded dirt or mulch at the base of the plants
or covered them in leaves last fall to prevent winterkill? I
just planted a dwarf fiesta forsythia. Since Bismarck is
technically Zone 3 and the barberries and the forsythia have
northern exposure, should I somehow cover the base this fall
also to prevent winterkill? (Bismarck, N.D.)

A: Barberry bushes seldom do well in our region, so I would
encourage you to opt for something else. They are the
alternate host for stem rust on our cereal crops. Since the
forsythia is being established this early, I see no need for
providing cover. If it makes you feel better to do so, go
ahead. I never have known any forsythia that died because of
winter problems.

Q: I have horseradish that keeps coming back in my garden
area. It is irritating me to no end. Since I have clay soil, I
am thinking about pouring a concrete slab for a patio over the
area where it is coming up. Do you think this will eliminate
the horseradish or will it spread underneath and pop up
somewhere else? Is there anything else I can do? (e-mail

A: Thanks for the e-mail about horseradish! Let this be a good
lesson for those who are contemplating growing this plant that
is impossible to get rid of! Concrete has been known to do it
in. If you can, prior to pouring the concrete slab, do all you
can to dig out the remaining rhizomes. Then pour the concrete
nice and thick!

Q: I live in North Branch, Minn., which is right on the border
of Zone 3 and 4. We bought a royalty crab tree from our local
nursery eight years ago. It has beautiful foliage in the
spring and early summer. However, it begins to lose its leaves
in early July. Is there something wrong with the tree? Is
there something we can do to prevent this from happening? Our
neighbors have the same tree and problem. (e-mail reference)

A: This is likely a foliar disease known as apple scab. There
is a lot of it going around this year. Spray the tree with a
Bordeaux mixture for now and be sure to pick up all the fallen
fruit and leaf litter this fall. Next spring, spray the tree
with lime-sulfur while dormant to protect and "sanitize" the
tree. As the foliage unfolds, spray with Funginex, a Bordeaux
mixture or Captan fungicide.

Q: I have an 11-year-old maple tree that has developed a long,
vertical gash in its bark. I first noticed it when I saw
rainwater flowing along a track that developed in a depression
on that side of the tree. The bark became slightly rotted
because water was trapped inside. I stripped it to good wood.
Is the tree going to recover? Should I plug the gap (inch
wide) with tar? The leaves this summer are perfect. (e-mail

A: The tree should recover, but don't touch the wound with
anything resembling a sealer. The tree should form new bark
tissue that slowly will roll over the wounded area. You did
the right thing in cutting the rotted bark back to fresh wood.

Q: I started six leaves from three different African violets.
Three of them are thriving and beginning to develop into real
plants, but I have tiny gnatlike flying insects around the
soil. They look like fruit flies. I don't want to kill the
plants. Can you suggest what I could do to get rid of the
little flying pests? (e-mail reference)

A: Spray them with a pyrethrin-based houseplant insecticide.
Get it in a pump container, not an aerosol type. The aerosol
carrier tends to "burn" the foliage if sprayed too close. Get
the flies when they are in flight because this is a
contact-only material made from mum plants.

Q: What can I expect as far as the life expectancy of a
highbush cranberry shrub? (Moorhead, Minn.)

A: It possibly will live longer than you, but with indifferent
cultural care and bad weather, as short as a year. Most people
end up pulling them out and replanting with something else
after 15 to 20 years because they want a change of scenery!

Q: In my kitchen near a northern exposure window, I have a
very pretty, braided trunk Eugenia (Syzygium Paniculatum) mini
tree. I have had it for several years and am training it into
a nice topiary-style ball. I have two problems that may or may
not be related. Although I never let it completely dry out
(having learned the hard way), every couple of months it
decides to drop about 30 percent of its leaves. The fallen
leaves feel crisp. For the past few months, most if not all,
the new leaf growth is covered with a clear, very sticky
sap-type substance. I also noticed that the top edge of the
clay pot in which it lives is also sappy and sticky. The plant
never has done this before. I see this lovely plant every day
and it gives me a great deal of pleasure. I would love to help
it. Any diagnostic clues you can give me would be most
welcome. (e-mail reference)

A: This cause is spider mite feeding. Look closely at the
plant with a reading (magnifying) glass if necessary. You
should see their little webbing or crawlers on the foliage.
They insert their stylets into the leaf tissue and start
sucking out the liquid. The liquid passes through their bodies
and becomes a sticky sap, which eventually causes the foliage
to drop. Get a miticide at a local garden center and spray the
plant. Mist the foliage on a regular basis or run the plant
under a tepid shower every so often to help keep mites under


NDSU Agriculture Communication

:Source: Ron Smith, (701) 231-8161,
:Editor: Rich Mattern, (701) 231-6136,

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