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June
30, 2005
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: When should I power rake
and aerate my lawn? (e-mail reference)
A: The best time
is the first few weeks of May. By that time, you have mowed the lawn
a few times and the crowns, root system and rhizomes are anchored securely.
Q: Why would hydrangea plants
stop blooming after several decades? What makes it odd is that the plants
are located far apart and in different gardens. I didn’t do anything
different than before. I get plenty of foliage, but no blossoms. They
don’t seem to have any disease. Any ideas? (e-mail reference)
A: It could be an
improper pruning schedule, overfertilization with high nitrogen or too
much shade.
Q: We use horse manure on the
garden. Is it OK if I put manure (been in a pile for a few months) on
the garden now, till it and then eat raw carrots out of it in a few months?
I’m sure that putting the manure on in November and letting it sit
over the winter is the best. (e-mail reference)
A: It might be OK
if it is mixed with the usual straw. It depends on the amount of precipitation
that affected the pile over the past few months. I would go lightly
in case there is still a toxic load of salt in the manure. To be on
the safe side, it would be better if you could let it sit until this
fall and then till it in.
Q: I have several burr oaks
I would like to move. I have heard they have a long taproot, so cutting
it off would kill the tree. Is this true? (e-mail reference)
A: Moving mature
oaks gets more difficult with age. If you are going to move them, I
would suggest doing so with a tree spade early in the spring and before
leaf-out. In all probability, you have some loss, but that should not
keep you from attempting to save them.
Q: When is the time to spray
my fruit trees? (e-mail reference)
A: Spray the trees
with lime sulfur during the dormant stage. Use an all-purpose fruit
tree spray (insecticide/fungicide) when the trees are in the pink stage
and with a Bordeaux mixture and Sevin during the fruit-set stage. Repeat
the application in two weeks.
Q: I have a fungus on the lawn.
I believe we got the fungus from a lawn mower that is used at many homes.
Do you think that if I let the same person mow the lawn, I will never
get it under control? It already seems better with one spreading of Milorganite
and a fungicide. (e-mail reference)
A: Diseases can
be spread by lawnmowers. It would be unrealistic to think it wouldn’t.
Dollar spot is an environmentally triggered disease. Milorganite is
a good choice because it serves as an antagonist to the turf pathogen.
If you are convinced that the fungus got on your lawn that way,
you might encourage the mowing crew or individual to hose down the underside
of the mowers before using them on your lawn (good luck!).
Q: Some leaves on
my ficus tree have a shiny, sprayed look to them. They look like someone
opened a soda pop and sprayed some leaves. The leaves do not feel sticky
to the touch, but I can feel some texture. I’m trying to be as descriptive
as possible. I hope it makes some sense. Can you tell me what may be going
on with my tree? (e-mail reference)
A: In the past,
your ficus probably had a spider mite or scale infestation. The pest’s
secretions caused the shiny appearance on some of the leaves. I would
suggest wiping those leaves off with a damp rag to prevent other problems
from developing. Clean up any remaining critters that still may be hanging
around, so carefully inspect the branches. Remove them with your fingernail
or by wiping them off with an alcohol-soaked rag.
Q: A couple of years
ago we transplanted a young sugar maple tree from the family farm in Upstate
New York. I went out this morning and noticed all the buds except one
were nipped off by a rabbit or squirrel. Is there anything I can do to
help this tree survive? (Dell Rapids, S.D.)
A: Put some protection
around the tree and don’t allow it to become stressed this season.
Keep it evenly watered, but not soaked. It should recover. The protection
should be a fence or rabbit wire to keep the offending creature out!
I’m surprised that the rabbits waited until now to launch their
attack. They usually do most of their damage during the winter months.
Q: I bought a dracaena
“white jewel” a few months ago. It has done absolutely nothing!
I’ve tried to alter the types of light and water, but nothing has
happened. I repotted it a few months ago because I noticed the roots were
still in the shape of the original pot. The only Web sites that have any
information are written in European languages. I’d really like it
to do something because it is a cute little plant. (e-mail reference)
A: The “white
jewel” is a cultivar of the dracaena fragrans. The basic information
on growing dracaena is what you will have to go by because there is
nothing specifically written about the “white jewel” or
any other cultivars other than descriptive appearance terms. Dracaena
is a slow-growing plant. Any variegated cultivar that has a reduced
level of chlorophyll in the foliage will be even slower growing. Fast
growing houseplants drive their owners crazy with top-heavy growth and
often have insect or disease problems. My advice is to enjoy this lovely
plant in the temporary static state it presently is in. Rejoice when,
in a few months, it produces some new growth. I assure you it will happen.
Q: Are you aware of
a plant that gives off an odor that would act as a snake repellent? (e-mail
reference)
A: I don’t.
Sorry!
Q: What type of root does a
prickly pear cactus have? Is it a taproot or a fibrous root? I am doing
a school project on the prickly pear, but can’t find any information
on the type of root it has. Thank you for your time. (e-mail reference)
A: Cactuses have
extremely long roots to reach out through sandy, rocky soil. The roots
grow close to the soil surface to collect moisture from the occasional
rains that come into their environment. This makes them fibrous roots.
Because they are succulents, cactuses store most of their water in the
aerial part of the plant. Their thick rind and needlelike spines prevent
water loss.
Q: I’ve been
reading about the problems people are having with their maple trees. None
seem to have the problem we have. Our small, green-leafed maple tree is
around 35 years old and was doing well until last year, when the leaves
didn’t seem to open all the way. The same thing is happening this
year. Our son trimmed it and cut off a large branch, but we don’t
think that had anything to do with our problem. (e-mail reference)
A: It sounds like
the tree has a stem canker that is girdling it or it has armillaria
root rot. In either case, the tree is checking out. In essence, your
maple tree is taking its last gasps of life using the carbohydrates
stored in its stems. Soon the leaves will curl and dry. You might as
well plan to replace the tree. Before you do, try to find out what killed
it. Take the dead plant to a local nursery or contact the Extension
Service agent in your county. If that doesn’t work, send samples
of the tree to the local land-grant university plant pathology department
for analysis.
Q: I hope you can
answer a question for me. Last fall we bought a new home (the birches
sold us). A dump truck broke off a medium-sized branch about 10 feet from
the trunk. It is now spring and the tree is leaking sap. It has no smell
and is not sticky. How can I save this wonderful tree? (e-mail reference)
A: Make a clean
cut, with loppers or a saw, back to the trunk or a lateral branch. The
sap flow will not hurt the tree and will stop.
Q: Is it OK to trim
to the ground the new growth on my lilacs? I like the way the old growth
branches out because it gives the lilacs the bonsai look that I like.
(Watertown, S.D.)
A: It should not
hurt because that growth is all suckers.
Q: My son is wondering
how big his spider plant will grow. Does it depend on the size of the
pot or the amount of sunshine it gets? (e-mail reference)
A: I have no idea
what the final size of a spider plant will be. It spreads like a strawberry
plant and produces leaves from a central, depressed crown. It does not
grow upright. In a tropical habitat like Hawaii, it would spread and
become a very effective ground cover. I don’t think it will grow
beyond knee high.
Q: I am interested
in a recipe for a leaf cleaner/insecticidal soap mixture. How much dishwashing
detergent should be mixed in the water? The mixture would not contain
any insecticide, but I understand the combination of soap and water gets
rid of insects. Another reader wrote of noticing tiny insects while watering
a plant. When I water my plant, there are extremely tiny things that seem
to be jumping around the soil. (e-mail reference)
A: Purchase insecticidal
soap. Don’t try to make a concoction of your own because your
formula could damage the plant. Insecticidal soap will not cause problems
when used as directed. It contains no insecticide, just the necessary
fatty acids that are plant protective and effective at desiccating the
insects. I suggest wearing dishwashing gloves when using insecticidal
soap. Those jumpers that you see when you water are known as springtails.
Most feed on soil microbes, such as bacteria and mold, where high levels
of organic matter are present in the potting soil mixture. They are
more of a nuisance than anything else. Most people choose to live with
them. Applying an insecticide gets most of them, but not all. If they
really bother you, I suggest repotting with sterile or pasteurized potting
soil and using a clean pot.
Q: Growing up, we
had a weeping willow in our yard that tore up our septic lines. I just
received several pussy willows and would like to know if their roots are
as bad as weeping willow roots. (e-mail reference)
A: While all willows
have a proclivity for water-soaked soils, the pussy willow (Salix discolor)
is not nearly as invasive as its more famous cousin. I still would not
plant them over septic lines!
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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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