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Hortiscope

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

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a problem with my tomatoes. The tomatoes get small,
dark brown spots on the leaves. After that, the leaves turn
yellow and the brown spots grow together. I'm worried I'm
going to lose my tomatoes because it seems to spread fast.
What do I need to do? (e-mail reference)

A: You have blight, but I can't tell which one. Here is a
laundry list of what you can do to prevent it from spreading.
Pick off all infected leaves. Don't water overhead because the
splash is an excellent conveyor of the disease spores. Don't
overfertilize. Dig out the badly infected plants, but don't
hoe, weed or otherwise work the garden when dew is present on
the foliage. If you believe there is a need, get the
appropriate garden fungicide for vegetable crops and apply
according to directions. Typical fungicides include mancozeb,
benomyl and chlorothalonil.


Q: We are having problems with mushrooms coming up in our
lawn. The largest group is where we had to have an elm tree
removed because of storm damage. The tree was removed at least
three years ago, but the mushrooms still keep coming up. We
had an underground sprinkling system installed last year, so
the top layer of the sod and soil was removed and reseeded,
but that did not solve the problem. Is there anything we could
use to get rid of the mushrooms? (Mobridge, S.D.)

A: Not really. The mushrooms need to run their course, which
is digesting the decaying organic matter from the old tree
that was taken out years ago. If you back off on the watering
somewhat, that will stop or at least slow down the showing of
the mushrooms.


Q: You specifically say not to fertilize trees and shrubs. My
husband says the card that came with the bushes says to use
Miracle-Gro Quick Start, and to drive Miracle-Gro Tree and
Shrub Spikes into the ground around the tree. I believe you
100 percent, but I need a little "ammunition" to dissuade my
husband from using any fertilizer or spikes. (e-mail
reference)

A: Fertilizing trees and shrubs is not needed in 99 percent of
the situations at planting time. In the old days when I was
doing fieldwork as a landscape contractor, such fertilization
was standard operating procedure. Then research was conducted
at various universities around the country, most notably in
Oklahoma and Virginia, plus others as well. It was found that
such treatment had little positive effects on the plants when
compared with no treatment. Fertilizers simply added to the
expense. While a "shot" of Miracle-Gro Quick Start will not
hurt anything and may lessen some transplanting shock (during
the months of active growth) without adding significantly to
the cost of planting, the use of spikes are a waste of good
money. Have him take you out to dinner tonight or sometime
soon because it will do the trees as much good. Spikes are not
needed because they concentrate the nutrients in specific,
tight locations, so the roots will spread randomly following
the path of least resistance and mine the nutrients that
already exist in the soil. Adding more nutrients blindly is
like taking three vitamin pills when a qualified physician
recommends just one. If a little is good, more must be better,
which of course is wrong. Even in sterile soil, spikes still
would be the wrong choice because the nutrients in the spikes
would serve the plant much better evenly distributed
throughout the backfill soil, plus the cost per unit of
nutrient is the highest on the market. Everybody is marketing
these darn things because the consumer is purchasing them, so
why wouldn't they recommend them? They do contain fertilizer
and they can be driven right into the ground around the base
of the trees, but the simple fact is they are not needed. It
is like putting high-test gasoline in your car when regular
will do the job, so why waste the money? This doesn't make the
companies that sell these products "bad companies" because
they are simply responding to what the customers think they
want. The companies are reading their market, responding to it
and attempting to get a piece of that market for themselves. I
can't blame them for their business action, but it is my job
to point out whether or not such action will benefit the
consumer.


Q: I purchased a blooming African violet more than a year ago.
I kept it on my desk at work under fluorescent lighting. It
never bloomed after that initial blooming. Was there something
I should have done to get it to continue blooming? I didn't
give it any food and used purified water. (e-mail reference)

A: You did nothing wrong based on what you have told me.
African violets will flower when they have enough energy. They
get that energy from light. You might think about adding a
plant grow light to give it a little more of a boost. If you
are patient enough, the plant eventually will bloom under the
fluorescent lights. If it has been more than a year since you
made the purchase and are using purified water, you may want
to consider a small shot of African violet plant fertilizer to
help it along.


Q: I am writing about my radishes. The last couple of years
all I get is tops. I planted white globe, cherry and the red
and white varieties. I planted some early in April and more in
May. They all turned out the same. Out of three packages, I
got four radishes. I was talking to some friends and they had
the same problem. I used to have bowls of radishes to give
away. (e-mail reference)

A: All top and little or no bulb growth is commonly caused by
too much shade, seeding too thickly or planting in soils that
have too much nitrogen and too little potassium. Radish plants
need just the opposite, which is low nitrogen and high
potassium.


Q: We recently let our ficus get too dry (maybe 10 days
without water). It has lost tons of leaves. The branches that
have lost leaves are dry and brittle. One nursery told us the
branches would re-sprout leaves over time. What is the best
way to save the tree? Do I need to simply water it correctly
and be patient or do I need to remove all the dry branches?
How long will it take to come back? (e-mail reference)

A: Be patient and prune out the branches that obviously are
dead. Dead branches will not send out new growth. Establish a
regular watering regime based on season of the year and rate
of visible growth. As to the length of time it will take to
recover, I have no idea and neither does anyone else. It all
depends on the care it gets, its location and the vigor within
the plant.


Q: We were with a friend who wondered how the Bing cherry got
its name. Please share the answer with us. I'll see her next
weekend and definitely will let her know and about seven
others! (e-mail reference)

A: Seth Luelling was a skilled horticulturist. In the late
1860s, Seth cultivated the Bing variety notable for its large,
firm fruit and sweet flavor. He named it Bing after his
6-foot-tall Manchurian foreman and close friend. Bing worked
with Seth for 35 years until his contract was fulfilled and he
returned to China. Bing cherries continue to this day to be
the preferred fresh market cherry. If anybody is baking pies
using Bing cherries, I'll be glad to take one and sample it.


Q: I received a very large, full peace lily in April. I
repotted it because it looked potbound. Since that time the
leaves have been wilting and turning brown. I used Miracle-Gro
potting soil and a slightly larger pot. I have two cats. I
thought they were hurting the plant by rubbing against the
leaves. I put it on a stand, but it hasn't helped. I have it
in a south patio window, but also have a large tree outside
this window, so the light is not harsh. This plant has a lot
of meaning to me and I have never had this problem with
houseplants before. Could you please help me? (Hillsboro,
N.D.)

A: About the only thing I can advise you to do is try misting
the plant on a regular basis and setting the pot on a tray of
pebbles filled with water. They thrive in high humidity and
moisture. I'm assuming the plant is in a free-draining
container and that you dump off excessive water within 30
minutes of watering.


Q: I have had my aloe vera plant for a few months. When I
bought it, it was malnourished. I thought I could help it
recover, so I started watering it once a week. A couple of
weeks ago I noticed one of the leaves had turned brown at the
stalk, so I removed it. Then all the leaves began to grow
outward. I thought the leaves were growing outward because it
needed to be replanted. As I began to replant it, I noticed
that another leaf had turned brown, so I pulled it off. When I
did, half of the bottom stalk came off with it because it was
rotten. In essence, my leaves are growing outward horizontally
and the bottom half of the stalk has fallen off. Is there any
way to save my plant? It is very near and dear to my heart.
(e-mail reference)

A: Overwatering is the culprit, so back off. It will not
reverse the rot that has taken place, but you can pick off the
leaves from the stem and allow them to cure for a day and then
repot in pasteurized, well-drained soil.


Q: I (stupidly) forgot to water my dad's hydrangea
Sargentiana. It was sitting in the sun all day yesterday, so
the leaves have wilted. My dad will be back tomorrow. He is a
landscape gardener, so he will be mad! If you could tell me
the best thing to do for the plant, I would be eternally
grateful! (e-mail reference)

A: Soak it in distilled water. The plant will take up the
water and respond quicker than any other water with a salt
content. If anything, it will rehydrate the plant quickly. Of
course, get it out of direct sunlight as well.


Q: I have an approximately 25- to 30-year-old snake plant that
I inherited from my mother. I am not sure what species it is,
but it does not have the yellow rim around its leaves. My
question is about the yellowing that has occurred in the last
few days at the core of the stalk. The inner 5 inches of
stalks are yellowing while the rest of the stalks are green
and healthy looking. I am wondering about root damage or other
problems. I have to admit, I never have been that great at
watering it regularly. It has sometimes gone weeks to a month
without being watered. I never have had problems with this
plant before. I am wondering if the pot is too small or if
there is a problem with the soil or drainage. I definitely do
not want this plant to die. It has been around as long as I
have. (e-mail reference)

A: You probably have some root rot taking place in a plant
that old. Remove it from the pot and divide the crown. Get rid
of anything that looks like it might even have a little rot.
Take a couple of cuttings as well. The cuttings should be
about 8 or 9 inches long. Stick them in a sand/peat mix and
keep moist. In two months, a new plant will appear from the
base and the cutting leaf itself eventually will deteriorate,
which you can then dispose of. This gives you a little backup
insurance in case something happens to the mother plant. Like
any houseplant, don't overwater, keep it in a container that
is free-draining, and after watering, dump out the excess
water.


Q: I have a low area that has collected too much water this
year and killed my four lilacs. Are there any flowering bushes
that would do well in a bed that will stay wet in future
years? (e-mail reference)

A: Yes, pussy willow or any of the willow species.


Q: I have a hosta question. Every year my hosta has increased
in size, but this year it is half the size of the year before.
The plants are not being eaten by slugs (yet) or any other
insect. The leaves look fine. Would there be a reason for
this? (e-mail reference)

A: Usually, half the size means that something is wrong in the
root system. It is often the start of root rot. If you are
game, dig up one of the plants in question and inspect the
crown and roots. If it appears healthy, then my next best
guess is that the foliage was damaged or removed early last
year and not enough carbohydrates were stored to produce the
typical foliage.

----

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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