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August
31, 2006
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: The leaves on my
pepper and basil plants have holes in them. Obviously, some insect is
eating the plants. What can I do to prevent this, but still be able to
use the basil in my cooking without toxicity problems? (e-mail reference)
A: That is a tough
question. I'd suggest using Bt or an insecticidal soap. The Bt will
take care of them (assuming they are caterpillars) when they come back
to feed. The insecticidal soap is effective when the insect is present
and contact can be made.
Q: The leaves on my
trees have green bumps with brown spots and the leaves are curling. Is
it too late to do any spraying? Should I do something next spring? Will
it harm the trees because this has been going on for a number of years?
Thank you for your time. I look forward to your column every week. (Valley
City, N.D.)
A: The green bumps
are from midges stinging the foliage in the early spring as the leaves
begin unfolding. The brown spots and curling leaves are likely the result
of anthracnose or late-spring frost damage. Next spring, while the trees
are still dormant, spray them with horticultural oil and lime sulfur
at the same time. The dormant oil will help control the insect pests
and the lime sulfur may take care of the fungus disease on the leaves.
Spray with a Funginex or Bordeaux mixture when the leaves unfold. Thanks
for the nice comments about the column!
Q: Can you help me
identify a very fine, long, sprout-type weed that a local homeowner found
in her garden? It has a long stem with very small, white flowers on the
ends of the stems. It was found growing around some flowers she had planted
from seed. The weed is spreading. Could this have come in with the flower
seed? Also, is there a cottony scale that attacks cotoneaster? The leaves
are gathered in almost glued masses around the stems. Fine, pure-white
cottony material surrounds some of the masses and partially travels along
some stems. I found one small, 1/4-inch larval crawler, but only one.
I'm also wondering about uglynest caterpillar. (e-mail reference)
A: The weed appears
to be dodder, which is a parasitic weed that only grows by penetrating
the tissue of host plants to obtain water and nutrients. Seedlings must
attach to a suitable host within a few days of germination or they die.
Threadlike, leafless stems twine around the host plants, which eventually
creates a tangled mat. Each plant produces thousands of hard seeds that
can remain dormant in the soil for years. The beast attacking the cotoneaster
is probably the pear slug. It has nothing to do with pears, so let's
call it a cotoneaster slug, which also has nothing to do with slugs!
It simply is the larvae of sawflies that have a taste for cotoneaster.
The problem can be controlled by spraying with Sevin or Orthene.
Q: I am looking for
three varieties of Kentucky bluegrass that will be the first to be green
in the spring. My friend is planting a new lawn and wants to be the first
to mow in the spring! He plans to drill the seed into the ground in early
September. (Fargo, N.D.)
A: For early greening
in the spring, go for the common cultivars. They are most often selections
made from the Midwest region and often selected from pasture environments.
They produce seed in abundance and inexpensively. The most commonly
available cultivars are kenblue, South Dakota common, park, alene and
Huntsville. Keep in mind that these grasses do not respond well to a
lot of tender, loving care. If given, the result is disease problems.
The cultivars come out of winter dormancy early, respond to the changing
growing season, green when it rains on a regular basis, turn brown when
it doesn't and regreen with the rains and cooler weather of fall. For
the best results, fertilize once a year in the fall and mow high (3
inches) all growing season. These grasses usually are a major part of
a blend. There often is more than one type of cultivar in a mixture
or blend.
Q: I’m trying
to find a way to keep my dog out of my flower garden. The dog likes to
dig a hole and then lie there. If there are some plants in his way, he
scratches them out of his way and continues to dig a hole. (Langdon, N.D.)
A: Try Liquid Fence
sprayed around the garden, especially where he likes to lie down. It
keeps bunnies and deer away, so it might work on dogs. However, I sometimes
wonder if any odor is strong enough to be offensive to dogs!
Q: I have a rather
large dogwood in my backyard that is growing clusters of little, light-green
berries. I also have a 1 1/2-year-old daughter who loves to pick them
off. I am forever trying to make sure she doesn't eat them (I think a
couple have made their way into her mouth). Are they poisonous? (e-mail
reference)
A: They are not
poisonous, but it is still a good idea to be vigilant because she could
easily choke on a berry at that age.
Q: I have several
emerald green arborvitaes that I would like to propagate. I doubt I would
ever find this specific genetic tree again. I've been looking through
your Web site and others, but can't find anything on how to propagate
arborvitaes. Can you help? (e-mail reference)
A: Look again, but
this time go to www.ext.nodak.edu/extpubs/plantsci/landscap/h1257.pdf.
The site doesn't address the emerald green or other arborvitaes specifically,
but the generic information also applies to this plant.
Q: I've heard that
if you cut the top off corn, it will grow taller and produce more. Is
this true and where do you cut it? Also, half my corn stalks are tall
and the other half short. It's like going down the line from tallest to
shortest. What causes this problem? (e-mail reference)
A: I have grown
corn for commercial purposes and worked for farmers who did the same.
We never cut the tops off because it makes no sense if you understand
the growth of monocots, which corn happens to be. The problem could
be water or nutrient availability or sunlight exposure. Something in
the environment is not uniform.
Q: I know your site
is dedicated to horticultural questions, but I am hoping you can direct
me. I am looking to buy picked and hopefully dried chokecherries. They
do not grow with any reliability in eastern Connecticut. If you or any
of your colleagues, friends or family members have any to sell, I would
be thrilled to buy them. I'd like to get several gallons of dried berries,
but any amount would be appreciated. Thank you for your time. I can be
reached at leslie@theislands.com.
(e-mail reference)
A: I don't know
of anybody, but by the time this hits the papers in a couple of weeks,
you may get some kind of response that could fulfill your desire. Hang
in there!
Q: I have a Canadian
red cherry tree that provides beautiful shade for my house, but the tree
has black knot fungus. I’ve had professionals here to treat the
disease with deep-root fertilization, but the disease continues. Every
year I remove the limbs that have the black knots. This year the tree
is weeping globs of sap from the main trunk and secondary limbs. It breaks
my heart to have to destroy this tree, but I do not think it's going to
make it another year. Any input on this would be appreciated. (e-mail
reference)
A: As what often
happens with plants, when a primary pathogen weakens the plant, such
as this cancer does to this tree species, secondary pests (in this case
borers) move in for the kill. I'm sorry to say that you are probably
better off having the tree removed based on what you have told me.
Q: My carrots are
a nice size and taste great as usual. However, every fifth or sixth carrot
I pull has one main top, but has five or six legs. Can you tell me what
would cause this? Also, my sister has been pulling out white carrots.
What causes this problem? (e-mail reference)
A: It could be injury
to the growing point from soil insects or nematodes. It also could be
physical injury from a stone, aggressive cultivation or a hard physical
object in the soil. The off-color is usually a result of environmental
extremes, such as high soil moisture from continuous or nearly continuous
rain or irrigation. It also could be caused by extremely high temperatures.
Q: My wife purchased
a self-watering container system from a catalog house last spring. We
planted three tomato plants in the container, but found out it was one
too many. The plants shot up and had lots of fruit, but when the fruit
started to ripen, the bottoms turned black. Some of the fruit have small,
black insect casings attached. At least I think they are insect casings.
The inside of the fruit is contaminated beyond the black exterior. Also,
the leaves started to turn yellow after 30 to 45 days. Any ideas? (e-mail
reference)
A: My faith doesn't
extend to automatic or self-watering containers. To grow good fruit
requires human judgment, which these take away. Secondly, what you saw
getting started probably was blossom end rot. This is caused by a cell
breakdown on the blossom end of the fruit (imagine that!) from insufficient
calcium being transported to the forming cell tissue at that point.
The cells collapse and the secondary organisms that cause the rot you
see make an appearance. Generally, it is confined to certain cultivars
of tomatoes, the first fruit set or plants that are under accelerated
growth. The yellow leaves could be caused by too much water in a poorly-drained
container, gray leaf spot or early blight. These are pathogens brought
on by heavy dews and frequent rains where the foliage has not been allowed
to dry sufficiently. Both can be controlled with fungicides, but at
this time of the season, I don't recommend it.
Q: Do you have any
suggestions for a fast-growing, disease-resistant, shade tree to plant
in West Fargo? (e-mail reference)
A: How about elms?
Washington, discovery, new horizon, cathedral and vanguard are all disease
resistant. You could plant silver cloud, autumn spire, northfire or
firedance maple trees. The freeman maple is a hybrid of the red and
silver maple using the blended good qualities of both species.
Q: We have a plum
tree that has some healthy and ripening plums. However, some of the plums
have small, cream-colored spots of varying sizes that are rotting. Some
of them have a colorless gel on them. (e-mail reference)
A: Dispose of those
that are showing the symptoms you describe. Pick up all dropped fruit
and dispose of it. Spray the tree next spring, before new growth emerges,
with dormant oil. At blossom drop, spray with an insecticide, such as
Sevin.
Q: I have several
volunteer trees on my land (cottonwood, ash, elm and hackberry). I would
like to transplant them to another area to keep them growing. Can you
tell me how and when to do this? (e-mail reference)
A: Do it this fall
after the leaves have dropped or early next spring before they leaf
out. Dig as much of the root up as possible and then plant immediately
at the same depth.
Q: I read all the
information on preserving flowers that you have on the Internet. Can I
use one of the methods you describe for preserving big, wild mushrooms?
I would like to use them with a flower arrangement. I would appreciate
whatever information you can give me. Thank you so much. (e-mail reference)
A: Sorry, I don't
know the answer. You might check out the following Web site, http://cabd0.tripod.com/cabsmushroompage/id9.html,
to see if there is anything there that will answer your question.
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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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