Horticulture 2020 Newsletter

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VEGETABLES
Controlling Weeds in Home Garden Asparagus Beds
The best time to control weeds in asparagus is early spring before
the asparagus emerges. A light tilling (or hoeing) that is shallow
enough to avoid the crowns will eliminate existing weeds. Many gardeners
like to mix in organic matter during the same operation.
Herbicides can be used before asparagus emerges as well. Glyphosate
(Roundup, Killzall) will kill weeds that are actively growing, and the
preemergence herbicide trifluralin can be used to kill weed seeds as
they germinate. Trifluralin is found in several products, but not all of
them list asparagus on the label.  Those that do have asparagus on the
label include Miracle-Gro Weed Preventer Granules and Monterey Vegetable
and Ornamental Weeder. Mulch can also be used to keep weeds from invading.
No herbicides can be used during harvest. The end of harvest
presents another opportunity.  Remove all fern and spears and apply
glyphosate (Roundup) to control virtually all of the weeds present.
After the harvest season is past and the asparagus starts to regrow,
options are limited. Products that contain sethoxydim can be applied to
asparagus to kill annual grassy weeds such as crabgrass. Sethoxydim has
no effect on broadleaves including asparagus. Two sethoxydim products
available to homeowners and labeled for asparagus are Monterey Grass
Getter and Hi-Yield Grass Killer. With broadleaves, the only option is
to pull them and look forward to next year. (Ward Upham)

Remove Fern on Asparagus
If you haven’t removed last year’s growth from asparagus plants,
now is the time.  Old growth can be removed from the site and discarded
or composted.  Another option is to mow the asparagus patch.  Burning
can also be used but only if it is safe and legal to do so.  A light
tilling (or hoeing) that is shallow enough to avoid the crowns may help
work in the old growth into the soil as well as control weeds.
Asparagus comes up around early April in Manhattan but will be
earlier in southern Kansas and a bit later further north.
Asparagus benefits from a fertilizer application after harvest but
not now. Fertilize according to a soil test or add 1 to 2 pounds of a
10-20-10 or 11-15-11 fertilizer per 20 feet of row immediately after
harvest. If a soil test shows that only nitrogen is needed, apply1 pound
of a 16-0-0 product or ½ pound of a 30-4-5, 27-3-3 or similar fertilizer
per 20 feet of row. Most of these high nitrogen fertilizers are lawn
fertilizers but will work well for this purpose if they do not contain a
weed preventer or weed killer. The fertilizer should be watered in with
1/4 inch of water.  (Ward Upham)

Help for Vegetable Gardeners
Kansans that are new to vegetable gardening often don’t know how
much of each crop to plant. K-State Research and Extension has a
publication that can help. The “Vegetable Garden Planting Guide” gives
information on the size of planting needed per person and the average
crop expected per 10 feet. Also included is a garden calendar
highlighting suggested planting dates and expected harvest dates. Crop
specific information is detailed including days to germinate, plants or
seeds needed per 10 feet of row, depth of planting, spacing within the
row and spacing between rows. You can find the publication at your
local county extension office or online at:
http://www.ksre.ksu.edu/bookstore/pubs/mf315.pdf .  If you don’t know
the location of your county extension office, see
http://www.ksre.ksu.edu/Map.aspx.
Another, more in-depth publication titled the “Kansas Garden Guide”
is also available. This 77-page booklet has sections on planning a
garden, composting, improving soil, seeding and planting, garden care,
watering, planting gardens for fall production, insect and disease
control, container gardening, season extension and harvesting and
storing. This is followed by an extensive section on how to grow
specific vegetables and herbs. You may order the print publication at
http://www.ksre.ksu.edu/bookstore/Item.aspx?catId=534&pubId=8219 for
$6.10. This web page also provides a link to a free PDF copy of the same
publication.
These publications can also be useful for experienced gardeners.
(Ward Upham)

ORNAMENTALS
Brown Coloration on Junipers
Certain eastern redcedar and various other junipers are showing a
brownish cast when viewed from a distance. This may be the male flowers.
Male flowers are on the tips of the leaves and look somewhat like a
cross between a miniature hand grenade and a pinecone. Shaking the
branches on dry days will often result in a cloud of pollen being released.
Most junipers are dioecious, meaning they have both male and female
plants. About half the junipers (the males) will have this coloration.
The female flowers are much less obvious. If you have clients who are
concerned about this brown coloration, have them check the plants to
ensure the male flowers are the cause. If they are, assure them that
this is normal and will fade with time. (Ward Upham)

Ten Rules for Planting Trees
Before you begin spring landscaping, here are some tips on planting
trees.
1. Select the right tree for the site. To avoid serious problems,
choose trees that are adapted to your location. Consider whether the
tree produces nuisance fruit or if there are disease-resistant varieties
available. For example, there are a number of crabapple varieties that
are resistant to apple scab and rust diseases. Also consider the mature
size of a tree to be sure you have enough room. See
http://hnr.k-state.edu/extension/info-center/recommended-plants/index.html
or ask a local nurseryman for suggestions for trees adapted to your area.
2. Keep the tree well watered and in a shady location until
planting. When moving the tree, lift it by the root ball or pot and not
by the trunk.
3. Before planting, remove all wires, labels, cords or anything
else tied to the plant. If left on, they may eventually girdle the
branch to which they are attached. The root flare (point where trunk and
roots meet) should be visible. If it isn’t, remove enough soil or media
before planting so that it is.
4. Dig a proper hole. Make the hole deep enough so that the tree
sits slightly above nursery level. Plant the tree on solid ground, not
fill dirt. In other words, don’t dig the hole too deep and then add soil
back to the hole before placing the tree.
The width of the planting hole is very important. It should be
three times the width of the root ball. Loosening the soil outside the
hole so it is five times the diameter of the root ball will allow the
tree to spread its roots faster.

5. Remove all containers from the root ball. Cut away plastic and
peat pots; roll burlap and wire baskets back into the hole, cutting as
much of the excess away as possible. If you can remove the wire basket
without disturbing the root ball, do it. If roots have been circling
around in the container, cut them and fluff them out so they do not
continue growing so that they circle inside the hole and become girdling
roots later in the life of the tree.
6. Backfill the hole with the same soil that was removed.
Amendments such as peat moss likely do more harm than good. Make sure
the soil that goes back is loosened – no clods or clumps. Add water as
you fill to ensure good root to soil contact and prevent air pockets.
There is no need to fertilize at planting.
Note: Adding organic matter to larger area than just the planting
hole can be beneficial, but it must be mixed in thoroughly with the
existing soil and should “feather out” toward the outside edge of the
area. Adding amendments to just the planting hole in heavy soil creates
a “pot” effect that can fill with water and drown your new tree.
7. Don’t cut back the branches of a tree after planting except
those that are rubbing or damaged.  The leaf buds release a hormone that
encourages root growth. If the tree is cut back, the reduced number of
leaf buds results in less hormone released and therefore fewer roots
being formed.
8. Water the tree thoroughly and then once a week for the first
season if there is insufficient rainfall.
9. Mulch around the tree. Mulch should be 2 to 4 inches deep and
cover an area two the three times the diameter of the root ball.
Mulching reduces competition from other plants, conserves moisture and
keeps soil temperature closer to what the plants’ roots prefer.
10. Stake only when necessary. Trees will establish more quickly
and grow faster if they are not staked. However, larger trees or those
in windy locations may need to be staked the first year. Movement is
necessary for the trunk to become strong. Staking should be designed to
limit movement of the root ball rather than immobilize the trunk. (Ward
Upham)

FRUIT
Frost Tolerance of Apricots and Peaches
Growers of apricots and peaches often wonder at what temperature
fruit buds are killed especially in years where we have an early
spring.  These two tree fruits bloom very early and are often caught by
a late frost. The following will give you some guidelines but remember
that the actual damage is going to be influenced by the weather before
the temperature drops. An extended warm spell before the cold snap may
result in more damage due to a loss in cold hardiness. The stages listed
are for the fruit buds.

Apricot
Stage    10% Kill (°F)     90% Kill (°F)
First white    24    14
First bloom    25    19
Full bloom    27    22
In the Shuck    27    24
Green Fruit    28    25

Peach
Stage    10% Kill (°F)     90% Kill (°F)
Swollen bud    18    2
Half-inch green    23    5
Pink    25    18
Bloom    27    24
Petal fall    28    25
Fruit set    28    25

To check for low temperature injury to fruit buds or blossoms, use
a sharp knife and cut them in half longitudinally (from top to bottom).
If the tiny seed in the center is white to cream color no damage has
been done. But if the seed in several buds or blossoms is dark brown or
black, it has been killed.
It is possible to give some protection to blossoms from freezing by
covering the tree with a bed spread, blanket or similar fabric but the
material should reach the ground so that heat given off from the soil is
captured.  Old-fashioned Christmas lights distributed through the tree
will help to give added protection. The newer, smaller Christmas lights
do not give off enough heat and are not recommended. Of course the
practicality of this method of protection depends upon the size and
number of trees and access to electricity.
Sprinkling the tree with water throughout the freezing period can
also protect the blossoms but is a dangerous option. Sprinklers should
be started before the temperature drops to freezing to be sure ice does
not  block the garden hose or water line. Continue until the temperature
warms. With this protection method, there is the potential of creating
an ice storm. If temperatures remain below freezing for several hours,
ice will accumulate on the branches and limbs. The weight from the ice
may cause branches and limbs to break causing severe, and possibly
permanent, damage to the tree structure. Also, if water drainage from
the soil is slow and the water displaces oxygen from the roots, damage
to trees may result. (Ward Upham)

TURFGRASS
Managing Turf in Shade
Turfgrasses differ in their capacity to grow in shade. Among Kansas
turfgrasses, tall fescue is the best adapted to shade though it isn’t
all that good.  Although the fine fescues (i.e., creeping red, chewings,
hard and sheep fescues) have better shade tolerance, they lack heat
tolerance and typically decline during hot Kansas summers. The
warm-season grasses have poorer shade tolerance than cool-season
grasses, although zoysia does better than Bermuda or buffalo. Where
shade is too heavy for fescue, there are other courses of action. The
most obvious but often impractical option is to either remove trees, or
to prune limbs and thin the tree canopies. Grass will do better under
openly spaced trees than under closely spaced trees. Pruned limbs and
thinned canopies will allow more sunlight to directly reach the
turfgrass. If possible, raise the mowing height in the shade to
compensate for the more upright growth of the leaves, and to provide
more leaf area for photosynthesis.
The thin, weak turf in the shade may tempt you to fertilize more.
Remember the problem is lack of light, not lack of fertility. Too much
nitrogen in the spring causes the plant to grow faster and may result in
weak plants. The nitrogen rate for shaded grass should be cut back to at
least half of that for grass in full sun. Late fall fertilization after
tree leaves have fallen, on the other hand, is important for shaded
cool-season turfgrasses and should be applied at a full rate. Irrigate
infrequently but deeply. Light, frequent irrigation may encourage tree
feeder-roots to stay near the surface, which increases competition
between the trees and the turf. Restrict traffic in the shade.
Another option is to reseed areas with heavy shade each fall. The
turf will look good during the fall and spring and then likely fall
apart when the stresses of summer hit.
None of these options is very attractive.  This is one of those
problems in which there is not a good answer.  Many times, the best
choice for shaded areas is switch from a turfgrass to a more
shade-tolerant plant. For example, periwinkle (Vinca minor) is much more
shade tolerant than any turfgrass adapted to our area. Another option is
simply to mulch the area where turf doesn’t grow well. The trees will
love the cool, moist soil and the absence of competition. (Ward Upham)

Contriubtors: Ward Upham, Extension Associate

Division of Horticulture
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
(785) 532-6173

For questions or further information, contact: [email protected] OR
[email protected]
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Extension Service K-State Research and Extension is an equal opportunity
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Extension Councils, and United States Department of Agriculture
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