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August
19, 2004
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: My ficus looks
healthy, but some leaves are gooey with a film created by tiny, brown
spider mites. The film is falling on my furniture under the tree. If using
an insecticide is advised, can I order it by telephone or Internet? (e-mail
reference)
A: Purchase a miticide,
not an insecticide. You can order it over the Internet if you wish.
Before doing that, I would suggest using an insecticidal soap such as
Schultz's or Safer's. Insecticidal soaps are less toxic.
Q: My hollyhock leaves
are turning yellow and getting spots on them. For the past two summers,
I have been removing bugs by hand. The bugs seem to be able to fly short
distances. Any ideas? (e-mail reference)
A: The insect is
the hollyhock weevil, which is related to the boll weevil. Your hollyhock
plants could also be getting a rust fungus, which is very common.
Q: About three weeks
ago I planted 10 tower poplars in my back yard. I chose this tree because
I read they are fast growing and make good privacy screens. Our back yard
is right off a busy street. However, after reading some of your columns,
I'm having second thoughts and wondering if I made a mistake. In addition,
at least one of them appears to be dying and four others seem to be heading
in the same direction. The leaves are turning brown and falling off. I'm
so disappointed, but I don't know what to do. Should we take them all
out and replace them with better trees or can we save them? Should we
replace the sick ones? (e-mail reference)
A: At least you
didn't plant the Lombardy poplar, which is the worst of them all! The
tower poplar is a hybrid and is considered an improvement over the Lombardy
because the disease pressure isn't as great. It does sucker, which can
drive people crazy. I have seen healthy tower poplars that look terrific,
but many succumb to leaf spot and canker diseases. You have to accept
that, if you plant a poplar species, you are very likely to have some
disease or insect problems at some point. I would suggest removing the
trees that have problems and replacing them with populus tremula erecta.
Its common name is upright European aspen. Of all the poplars, it has
the best resistance to disease and insect problems.
Q: Last year I planted
12 different colors of daylilies. This year they are all yellow or orange.
What happened? If you have the answer to this mystery, I would appreciate
it very much. (e-mail reference)
A: I don't have
the faintest idea! Perhaps one of our readers will know and pass the
information on to me so I can give everyone an answer.
Q: My jade is 10 years
old. It has three main trunks. Each trunk is about 2 inches in diameter.
We recently repotted it. It's very heavy on one side because the only
place in winter available is near a fireplace with bright, indirect west
light. All winter we found dried-up black leaves while others got rubbery
and shriveled. Recently we've had branches drop off that were shriveled
and soft on the stem near the break. Since repotting, it's outside on
a west porch. One of the three branches leaning onto the side of the pot
has developed a fissure near the base. The fissure is opening wider each
day to the point that it's nearly through the trunk. I am frantic as to
what to do to save it before I lose the whole plant.
A: I would suggest
taking some branch ends and rooting them to start over. Jade plants
cannot successfully be band-aided together very well. This plant species
seems to be the bane of many houseplant lovers. The basic problems stem
from insufficient light, too much water and over-fertilization. Also,
if the plants were pinched at the terminal ends of their branches on
a regular basis (the first inch of the branch pruned off), the resulting
plant would be a compact, balanced beauty and not a lanky, weak-stemmed
freak that gets tied up with clothesline and bedsheet pieces. If you
can, take cuttings about 4 to 6 inches long and root them in a sandy/peat
medium. Give them supplemental light during the long winter months,
water when the soil mass is dry and fertilize in response to emerging
new growth. This will give you plants from the original that you could
give to family or friends.
Q: We are attempting
to grow asparagus from seeds in our recently constructed greenhouse. We
planted them in 72 plug flats in late March and transplanted into 3-inch
pots in mid-May. About the time we transplanted, some of the tops started
turning brown and by now almost all of them have. I'm hoping this is a
case of premature dormancy. What should we do to try to save these plants?
(e-mail reference)
A: It sounds like
you may not have used sterilized or pasteurized soil. If you did, it
may have poor drainage and so it picked up a water mold. This could
also come from water splash if using an overhead watering system. Check
a few plants to see if there is any life remaining in the small crown.
If there is, then your assumption about premature dormancy was correct.
I don't know what else to tell you.
Q: We have a thundercloud
flowering plum. We were told it doesn’t bear fruit, but ours is.
Is it true the plums are poisonous? (e-mail reference)
A: Flowering plum
cultivars do bear small fruit. The seeds, leaves and bark are poisonous.
Of course, the exception is the fruit we eat. You will be fine if you
steer clear of the poisonous parts.
Q: We planted two
prairie fire crab trees three weeks ago. They looked beautiful until two
days ago. The leaves have turned yellow and are dropping off. There are
still some green leaves toward the top of the trees. The trees have received
plenty of water from rain and sprinkling. (e-mail reference)
A: They have probably
been overwatered. You should never have the water from a sprinkler impacting
directly on the foliage of a tree. The plant could have a leaf spot
or rust fungus. Back off on the water or redirect a couple of sprinkler
heads. Hopefully, you will be able to save the trees.
Q: I have a large
cottonwood (cottonless) tree in my yard. The tree splits into two major
trunks just above the ground. Last year one side of the tree lost most
of its leaves early and the branches looked like they had died. This year
that side of the tree is slow to get leaves and looks half dead. What
could be causing this? (Minneapolis, Minn.)
A: It could be armillaria
root rot, girdling cankers or a vascular disease like verticillium wilt.
Have an International Society of Arboriculture certified arborist inspect
the tree. There is a chance the tree can be saved, but not likely. More
importantly is the potential hazard such a declining tree may pose.
The arborist could identify the potential hazard and offer suggestions
on pruning or partial removal.
Q: I may have a problem
with my silver weeping willow. This spring it didn't leaf out as strongly
as past years. Last year I noticed small holes just into the bark. Because
of the distinctive pattern, there was no doubt in my mind the holes were
caused by a yellowbellied sapsucker. Can this bird kill the willow? I
now see the bird in the tree all the time. Should I get out the 4-10 shotgun
or do you have any suggestion? (e-mail reference)
A: Keep the shotgun
for something more important and legal than killing a yellowbellied
sapsucker. I doubt the bird will kill the tree; however his persistence
indicates that he has found a good hunting ground for food. While their
primary source is the sap, that sap also attracts insects which the
sapsucker consumes as well. For control, tactile repellents such as
Tanglefoot, Bird Stop and Roost-No-More are quite effective in some
cases, but are messy for the applicator to use. Some success has been
reported using propane cannons or electronically generated explosions
that vary in timing. If those options don’t work and the tree
continues to decline, a permit to kill the bird can be obtained from
the Animal Control Division of the USDA. The sapsucker is a migratory
species and is important in controlling unwanted insect pests such as
borers. The bird is protected under the Migratory Bird Treaty Act of
1918.
Q: While transplanting
my fern, I found a lot of these tater-type things. Can you tell me what
they are and if new ferns will grow from them? (e-mail reference)
A: They are fern
storage organs. Leave them alone and all will be fine.
Q: I planted two crabapple
trees last fall in a new housing addition. They seemed to be doing fine
until about three weeks ago. The dark pink looks like it has a white paint
or coating on the trunk and a few of the branches. I also noticed some
of the branches are bare. The white crabapple next to it now has the same
symptoms. (e-mail reference)
A: It could be cottony
cushion or some other species of scale insect. Take a twig with the
infestation on it to a local nursery for confirmation. Purchase horticultural
oil that will control these destructive pests. If they don't have the
oil, see if they have a systemic insecticide that will do the job.
Q: Along my workplace
parking lot and building is a row of Miss Kim lilacs. In front of those
are two rows of Stella de Oro daylilies. All were planted seven years
ago. In the last two years, the daylilies haven’t been blooming
as well as in the past. The lilacs are doing very well and have filled
out beautifully. I’m thinking they could be hindering the daylilies’
growth. We have a beautiful sea of green leaves on the daylilies, so they
look healthy. I don’t think any of the plants have been fertilized
since being planted. Would that help or will we have to dig up and separate
the daylilies? Since we are looking at approximately 100 plants just along
the parking lot, I’m hoping that digging and separating isn’t
the only option. (Fargo, N.D.)
A: Let's start with
the easiest option, fertilizing. If you can, apply a water soluble 20-20-20
material or something similar. It will not instantly bring them into
bloom, but should help if any of the big three nutrients are short.
If the lilacs are crowding the daylilies, do some selective pruning
on the lilacs to allow more direct sunlight to reach the lilies. Digging
and separating are the last option if the first two ideas don’t
work.
Q: I bought a yellow
tomato plant that was growing nicely until I transplanted it into a pot
using garden soil. I believe the soil has Miracle-Gro and fertilizer in
it. The plant is not dying, but it has now turned black and won't grow.
(Eureka, S.D.)
A: Obviously the
plant doesn't like where you placed it. If the pot doesn't freely drain,
that could be the problem. If the plant is black and not green, then
it is dead. I don't know what else I can say with the information you've
given me. Miracle-Gro potting soil is a quality product and has been
on the market for a long time. You might do a seed test using corn and
beans to see if they grow. If they do, then the problem isn't the soil.
Do you have a gardening
or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension
Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu.
Note to e-mail correspondents: please identify your location (city and
state) for most accurate recommendations.
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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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