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March
18, 2004
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: I noticed the question
about growing pecans in North Dakota. I found a hardy variety in the Miller
Nurseries catalog. It says this winter-hardy pecan will tolerate 30 below
temperatures and it lists zones 4-9, which is almost the same as their
hickory, which is a zone 4-8 and a black walnut, which is zone 5-9. (E-mail
reference)
A: Let me know what
kind of results you have. It would be great if you succeed because I'd
love to see pecans growing as a dependable nut crop in our zone. Pecans
taste good and are healthy for you.
Q: Are there any studies
on the various aspects of hardiness such as soil type, moisture, whether
the cold comes early or late, is the cold worse when it's accompanied
by wind, is it the branches or the roots which can't handle the cold,
is it worse if there are large temperature fluctuations or extended cold
spells? Does mulch help or hinder? What causes a variety to be hardier
than others? Is it genetic makeup? If one raspberry plant out of 10 survived
a hard winter, would the new plants from the one that survived be more
able to survive subsequent cold winters? I really would like to know the
botanical reasons rather than just take a company's word that a certain
variety is hardy in zone 4. (E-mail reference)
A: Hardiness can
be affected by nutrient level, water availability, whether or not the
plant has time to acclimate to our changing temperatures and whether
or not it can be "teased" out of a hardy state by fluctuating
spring temperatures. If a single plant survives a brutal winter while
the rest get wiped out, you can bet that plant will get a lot of attention.
Was it a fluke? Seed will be collected to see if any of the offspring
inherited a hardiness characteristic. Follow the dollars in some catalogs.
They might say a species will survive in zone 4 because they want to
expand their market.
Q: I have a 10-year-old
autumn blaze maple that has bark peeling off the trunk. It looks like
something is eating the bark. The peeling is on the south side of the
tree. What can I do to protect this wonderful tree? (E-mail reference)
A: Most likely nothing
is eating the bark. What you are seeing is weather damage from fluctuating
temperatures. This causes the wood and bark to expand and contract resulting
in the bark peeling off.
Q: I combined two
of my small peace lilies into a large pot. They looked wonderful but last
week one side of the plants became extremely droopy and some of the leaves
turned completely yellow. I’m not sure if they are going into a
rest period. What should I do? I also have a gorgeous elephant ear. The
middle stalks are standing straight but the stalks around the outside
have drooped. (E-mail reference)
A: Your peace lilies
are probably going into or attempting to go into a rest period. I would
let them do so for about six to eight weeks. Start watering again after
that. Your elephant ear is probably not getting enough light. If you
can, place it where there is strong indirect light or filtered direct
sunlight for part of the day. It should help the plant straighten up
or at least keep any more stalks from drooping.
Q: I have three rows
of trees approximately 120 feet long. One row has common lilacs that are
spaced five feet apart. The other two rows are green ashes that are spaced
eight to 10 feet apart. Each row is spaced 18 feet apart. I would like
to install a drip irrigation system this spring to reduce the time it
takes to water. I have 60 pounds per square inch on a 3/4-inch water supply
line. I would like to know what size water line and emitters I should
use. (Bismarck, N.D.)
A: You didn't say
if the supply line is copper, PVC or polyethylene. Without that answer,
I am going to make some assumptions. The flow capacity is 10 gallons
per minute or 600 gallons per hour, which is the figure you would be
interested in using. The lilac row would have 24 plants spaced five
feet apart. The ash rows would each have 12 plants, spaced 10 feet apart.
The total number of plants being irrigated would be 48 with each requiring
three point source emitters at two gallons per hour for a total of six
gallons per hour delivered to each tree. Six gallons per hour time’s
48 trees equals 288 gallons per hour required at the source. You have
plenty of leeway in your supply line with 312 gallons per hour left
over for future expansion if needed. Sixty pounds per square inch is
too high. It would blow the emitters out of the polyethylene line. You
need a pressure-reducing valve at the header line to bring the pounds
per square inch down to about 15 to 20. You should install a filter
at the header to prevent the emitters from clogging. You didn't say
what type of soil you have. I’m going to assume you have a loam
and not sand or clay. Run the system for two hours and then shut it
off. Check how much of the soil ball is wet. It should be wet beyond
the roots of the plants. If it isn’t, run it another hour or so
until that happens. That then becomes your watering time. You could
use 3/4-inch polyethylene line for each row and essentially lose nothing
to pressure friction. Run the lines down the tree rows and get a multi-outlet
emitter (pressure compensating) and some micro-tubing to insert into
the outlets. Bring each one up to the edge of the rootball, spacing
them evenly around each plant. Anchor them in some way to keep them
from being blown around by the wind. Be sure the bug caps are installed
over the end of the emitter tubing or else all kinds of stuff will crawl
in. Give the system about three years to establish the plants. Move
the emitters out a little farther each year to expand the root system.
Q: I have a Christmas
cactus that is wilting and looking pale and bleached. I put in into a
new, bigger pot and fertilized it. I give it as much sunlight as possible
and water about every three days. Any suggestions? (E-mail reference)
A: Back off on the
watering and don't add fertilizer. Water only when the soil is completely
dry. Fertilize when there is evidence of new growth. Don't try to force
it into growing with fertilizer. The plant does not need direct sunlight
so that could be causing the bleaching.
Q: We grow several
types of raspberries because we enjoy the jelly, preserves and wine we
make out of them. The raspberries we have are heritage, fall gold, latham,
black hawk and blackberry. How much should we prune each variety? From
what I understand, heritage should be cut to the ground in winter. Fall
gold should be cut to the ground to produce one large harvest versus two
smaller ones. Blackberry shoots that produced in the current year should
be cut.
I’m not sure
what to do with the latham or black hawk. (Lesterville, S.D.)
A: You are right
on the money with the heritage, fall gold and blackberry. Latham and
black hawk are both summer bearing. This spring cut the canes that bore
last year to the ground. Top off the growth that is going to produce
this year at about four feet. Throw some 5-10-5 or something close to
that around the plants and then stand back!
Q: I have two indoor
gloxinias that are very leggy and almost top-heavy. The leaves are slightly
curled but are still green. They get bright, indirect southern sunlight.
I keep the soil moist and maintain the temperature at 65 degrees. The
plants have not bloomed for a long time. Buds have appeared but then turned
brown. Can I cut off the leggy stem and hope that the tubers will grow
a new stem? (E-mail reference)
A: Gloxinia should
be allowed to go into dormancy. Your plants may be trying to tell you
that’s what they want to do. Allow them to dry down and then repot
in six to eight weeks using fresh potting media. Set the tuber in a
bright location but away from direct sunlight. Then start watering again
using tepid water. Do not get any water on the leaves.
Q: Can one corn stalk
grow alone where no other corn is planted? (E-mail reference)
A: You can grow
just one corn plant but you need to take the pollen from the tassel
and dust it on the silk. Full-size ears will not develop unless you
do that. It will grow as long as the seed is viable (alive), has adequate
warmth, light, water and nutrients.
Q: A source for sheepnose
apples is Miller Nurseries, 5060 West Lake Road, Canandaigua, N.Y. 14424-8904.
Call their toll free number, (800) 836-9630, for a catalog. I would like
to find a source for goldo apples. (Walhalla, N.D.)
A: Several readers
will be delighted to have this information! Perhaps someone will know
where to locate the apple variety you are looking for.
Q: My Christmas cactus
has healthy, dark green leaves and flowers several times a year. For some
time now whole branches fall off after flowering or even while the flowers
are open. It appears that the stem is rotting just above the soil line.
What can I do to save this plant? (E-mail reference)
A: About the only
thing you can do, based on your description, is to take some root cuttings
from the remaining healthy foliage. Stem cuttings are the best alternative
at this point because the plant sounds like it is doomed.
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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