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Hortiscope

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

Ronald C. Smith, Horticulturist
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NDSU Extension Service
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Q: I just happened across your Web site while researching a
problem I am encountering with an indoor, miniature orange
plant. I inherited the plant about two years ago and it is
flourishing. My only problem is that it produces so much sap
that it is ruining my house. There is a layer of tacky, clear
residue in a 6-foot circle around the tree. What is causing
this and can I do anything to limit it? (e-mail reference)

A: If you look closely, you will find aphids taking up
residency or spider mites. They are about the size of a period
in a sentence. Both pests will extract plant nutrients from
the leaf and stem tissue, which then passes through their
bodies as "honeydew," making everything it falls on tacky. I
would suggest moving it outdoors and giving the plant several
hard sprays of water. This will dislodge these pests and may
be sufficient so that the problem no longer exists. In
addition, by summering it outdoors, there is a chance that
natural predators will find the pests and wipe out the rest
for you. As a final solution, you can try Orthene, which has
miticide and insecticidal activity and is both a contact and
system material.


Q: We have some old lilac bushes on our lot line, but we are
not sure of their age. In the past, they have flowered nicely.
Adjacent to the bushes we have a wildflower/weed area. Last
spring, my husband burned off the wild area. This spring, the
lilac bushes did not bloom. My neighbor insists that we killed
the bushes. The bushes still have green leaves on them, so I
say they are not dead, but he is convinced we did something to
harm them. Could the fire next to the bushes have damaged the
soil or adversely affected these lilacs? Any ideas you might
have would be greatly appreciated! (e-mail reference)

A: Any plant that produces green leaves is not dead, so that's
the end of that argument. What the fire probably did is kill
the flower buds that were to bloom this year. Tell your
neighbor to take a deep breath and stay calm. The lilacs
probably will bloom next spring, assuming no more fires take
place and no one does any pruning this year from this point
on.


Q: About four years ago, a friend gave me some raspberry
shoots. Every summer I have great little leafy raspberry
bushes, but no canes or fruit. Can you tell me why? I suspect
too much or too little of something, such as potassium,
calcium or alkali. I have not been fertilizing the plants.
Thanks for whatever help you can provide. (Mansfield, S.D.)

A: The raspberry is a biennial cane, which means it is
vegetative the first year and bears flowers and fruits the
second year. Don't cut these back because they will be the
ones producing for you next year. If for some reason you have
not been pruning them back, then you may have a cultivar that
is not hardy for your area, so you should get it replaced. For
more information on raspberry culture, go to
www.ext.nodak.edu/extnews/hortiscope/fruitveg/rspberry.htm.


Q: I have tomato plants that are 5 feet tall. Can I snip the
ends off the branches to encourage fruit growth such as you do
with squash? I do pinch off the suckers between the crooks of
the branches. Thanks for any help you can give me. (Bismarck,
N.D.)

A: Pruning the plant will keep it compact. Many people do get
rid of the sucker growth that appears on the main stem. To get
larger, fewer fruit, remove any blooms that appear before
fruit set can take place. If you have overfertilized the
tomatoes, the growth will be mostly vegetative. In that case,
any pruning would be of little help.


Q: We have a three-year-old amur maple that has been healthy.
It has developed a 2-inch-long canker on the trunk 2 feet off
the ground. Using a sterilized knife, I cut out the canker.
The next day the area looked healthy, but had developed a bit
of a blackened area over it. I cut this off and sprayed sulfur
on it. The next day it again was covered in a dark, greenish
black, but less than the day before. I watered the tree and it
all came off. Is this oozing sap to heal the tree or is this
the bacteria from the canker? Should I continue to cut out the
black that appears or leave it be? Is there anything else I
can do to help this tree? Otherwise, it is growing healthy
leaves and the remainder of the trunk looks very healthy.
(e-mail reference)

A: If you are cutting back to healthy tissue, there should be
no strange flow of black, oozing sap. It is very unusual for a
tree this young and of this species to develop a canker
problem. Cut to where the bark is firmly attached to the trunk
and let it go. If the tree is going to heal, it will do so on
its own. Any spraying you might do at this point would do
little to no good. Young and otherwise healthy trees such as
this have the ability to compartmentalize wounds very quickly.
The tree begins healing by sealing off the outer surface, then
forming callus tissue, which gradually rolls over the wounded
area.


Q: I finally resorted to using a handheld mosquito fogger in
my yard because I could not access my perennial garden due to
those nasty skeeters. I fog when the bees and butterflies are
not active. I got to thinking that the chemical I am using,
which is the standard weak dose of Resmethrin (0.2 percent)
available at hardware stores, might kill the things that are
eating my plants, such as thrips, leaf rollers and miners,
aphids and spider mites. Would it be effective to just fog the
perennials and annuals in hopes of insect control without
having to spray liquid chemicals or soaps? The commercial
label was not specific on this, referring only to insects that
bother humans and not plants. (Moorhead, Minn.)

A: I am certain that the fogging you do to wipe out the
mosquitoes also will do a number on many of the plant-munching
bugs as well. Your intention is mosquito control, but flies,
thrips, and leafhoppers also are bound to be affected.


Q: I have six-year-old sweet autumn clematis that is diseased
for the first time. The leaves turn tan/brown, then die. New
growth still is occurring and flower buds are appearing. The
diseased leaves have "spiderlike webs" going through them, but
I cannot see any sign of insects. (e-mail reference)

A: It sounds like spider mites. Place a piece of paper under
some of the leaves that are affected and shake the branch or
leaves a little. If the specks that land on the paper move,
you have spider mites. If that is the case, get a miticide and
give the plant a good spraying. Also, a hard spray with plain
water may bring them under control.


Q: I have noticed in my yard that in at least two locations
there is a trail that has no grass growing on it. The trail
leads to a golf ball sized-hole running under my patio and
through some landscaping. The trail is about two feet long and
about an inch to an inch and a half wide. Do you have any idea
what might cause this kind of trail and what I could do to
prevent it? (e-mail reference)

A: This sounds like ground squirrels are taking up residency
on your property. Get a garden hose and force some water down
the hole. They almost always have more than one exit, so have
someone else on the lookout for a head or two to pop out of
the ground somewhere else and go scooting away. You can live
trap them or call in an exterminator to take care of them.


Q: We cut down four poplar trees last fall. Within the last
three to four weeks, we're being inundated with runners from
(we think) these trees all over our yard. We are planning to
have the stumps removed soon, hoping that will help, but is
there something we can spray to kill the runners? Any solution
you may offer will be appreciated. (Fargo, N.D.)

A: Let me use this as a lesson for all who read this. If your
intent is to remove a tree for any reason, unless it is a
hazard, wait until it leafs out completely in the late spring
and then flowers. Then remove the tree. Most of the energy to
produce suckers will have been spent in this surge of growth
and reproductive cycle, so the amount of growth from the
remaining roots will be minimal. To control the problem you
are having, treat them like weeds and spray with Trimec. The
Trimec will get translocated into the roots and provide an
effective kill. Don't expect it to work with just one
application. You should succeed with two or three
applications. If you apply it now, in midsummer, do so again
in the early part of September on the regrowth that shows up
then.


Q: How can I repair a large area of bark stripped off an old
oak tree? (e-mail reference)

A: With a sharp and probably large pocket knife. Cut back to
where the bark is attached to the wood below and leave it
alone from there. If the tree is otherwise healthy, it will
begin healing itself by producing callus tissue that will roll
over the open, stripped area in the next few years. Trees have
better defensive mechanisms than most people realize. With
their good intentions and wrong action, folks often slow or
totally inhibit the proper healing of their trees.


Q: An old boxelder has lost some bark on the bottom few feet
of the tree. There are small, eighth-inch or so round holes
drilled over the lower trunk. The holes are in the barkless
portion. A lot of sawdust is on the ground below it. Would
sapsuckers do that much harm or could borers be a possibility?
(e-mail reference)

A: That is an excellent symptom of borer activity.


Q: My African violets have little specks on the leaves, which
are limp. Are these bugs? While on vacation, the person
baby-sitting the house watered them from the top rather than
adding water to the pot. Could it be the white specks are from
overwatering? If so, what do I do? (e-mail reference)

A: It could be the water has chlorine in it and causing the
speckling. If the specks move or they appear (look at them
with a magnifying glass) to have inserted a mouth part, then
you've got a problem. My bet is they are water spots and not
insects. Don't worry if that is the case. Go back to your
usual cultural practices and the plants should recover.


Q: My peonies bloom well into the beginning of June. If I
didn't cut them for the flowers, would they bloom more than
once? (Minneapolis, Minn.)

A: Yes, in some cases they will bloom again, but not with the
vigor of the initial show of color.


Q: I planted a white ash called Junginger. I know we have too
much green ash in the Fargo-Moorhead area, but are white ash
susceptible to the same diseases as a green ash? Also, do you
have any opinions about Junginger? I hear it gets a nice
purple color in autumn, but can't seem to find much about it
on the Web. (Fargo, N.D.)

A: It is one of those trees with more than one name, depending
on where you make the purchase. It also is known as autumn
purple. Here is a brief synopsis of what I found on the Web.
F. Americana autumn purple equals F. Americana junginger. It
was discovered at the University of Wisconsin, Madison, by
Karl Junginger (1905-1991) of McKay Nursery, Waterloo, Wis. It
was introduced in 1956, has rapid growth, a rounded habit and
is seedless. It has a heavy, dark green foliage of pronounced
deep purple or mahogany in the fall or a mottled
yellow-orange. Unfortunately, white ash is plagued with
disease and insect problems too numerous to mention. I hope
this cultivar turns out to be an exception to the species.
Sorry, I don't know more about this tree. Keep me posted on
how it grows for you.


Q: I need your expertise! We have a lawn that has been taken
over by clover. We did one application of granular weed
killer, but it did nothing to alleviate the problem. What do
you suggest? Also, when is the best time to move perennials? I
need to thin out and relocate some of the plants. (e-mail
reference)

A: Glad to help! Granular herbicides typically have half the
horsepower effectiveness that the liquid applications do.
Also, the effectiveness is better if applied later in the
season. Toward fall, the material can be absorbed internally
and translocated to give a complete kill. Use Trimec because
it will control clover. Here are some rules in moving
perennials: spring flowering perennials, move in the fall;
fall flowering perennials, move in the spring, and midsummer
flowering perennials, move in spring or fall.

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NDSU Agriculture Communication

:Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
:Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu

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