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October
27, 2005
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
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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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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