FRUIT
Fruit Trees and Frost
If you are considering purchasing fruit trees this spring, there
are certain factors that should be considered for some of our fruit tree
species. Spring in Kansas is often unsettled with apricot and peach
tree flowers being very vulnerable to late frosts that can kill fruit
buds. Of course, the tree itself will be fine but there will be no to
little fruit for that year. Other species of trees can also be affected
but apricots and peaches are by far the most sensitive. Also, the
closer a tree is to full bloom, the more sensitive it becomes to frost.
Apricots are more likely to have frost kill flowers than peaches
because they bloom a bit earlier. Though there are late-blooming apricot
varieties, the differences between full bloom on early and late-blooming
varieties appears to be slight. Research at Virginia Tech in the 90’s
showed a maximum of a 4-day difference between early and late varieties.
However, in some years that may be all that is needed. The trees in the
study that were considered late blooming included Hungarian Rose, Tilton
and Harlayne. Harglow was not included in the study but is also
considered late-blooming. See
https://pubs.ext.vt.edu/422/422-761/422-761.html for more
info.
Peaches are next on the list for being likely to be caught by a
late frost. With peaches, two characteristics become important when
considering whether they will be damaged. Like apricots, bloom time is
very important but fruit bud hardiness should also be considered. In
this case, fruit bud hardiness refers to hardiness to late frosts rather
than the ability to survive extreme low temperatures during the winter.
Late bloomers included ‘China Pearl’, ‘Encore’, ‘Intrepid’, and
‘Risingstar.’ See
http://aces.nmsu.edu/pubs/research/horticulture/RR782.pdf . The
‘Intrepid’ cultivar also has shown excellent cold hardiness when in
flower. See http://www.google.com/patents/USPP12357
So, are there other considerations when looking at possible frost
damage? Location can be very important. Planting on a hill which allows
cold air to drain to lower elevations can help. Also, a location in town
will be more likely to have a warmer micro-climate than an exposed
location. Some gardeners will add a heat source under a tree during cold
nights if they are close to a building. Heat lamps and charcoal
briquettes are sometimes used but safety should be the first
consideration. (Ward Upham)
ORNAMENTALS
Dutch Elm Disease Resistant American Elms
Our John C. Pair Horticultural Center near Wichita established a
National Elm Trial in 2007 with 18 cultivars. All of these are Dutch Elm
Disease (DED) Resistant with 4 being true American elms. The cultivar
‘Jefferson’ would have been a fifth true American elm but proved to be
the same cultivar as ‘Princeton’. The remainder are either hybrids or
other elm species. The four true American elms are ‘Valley Forge’,
‘Princeton’, ‘New Harmony’ and ‘Lewis and Clark’ (Prairie Expedition).
All have shown excellent tolerance to DED. Characteristics listed below
are primarily from our study at the John C. Pair Horticultural Center
but storm breakage is from the University of Minnesota.
‘Valley Forge’
Survival: 100%
Crown Shape: Vase
Lacebug damage to foliage: Minimal
European elm flea weevil damage: Minimal
Storm Breakage: Fair
Comments: Strong grower, broad spreading
‘Princeton’
Survival: 100%
Crown Shape: Vase
Lacebug damage to foliage: Minimal
European elm flea weevil damage: Minimal
Storm Breakage: Fair
Comments: Impressive grower, upright habit, attractive tree
‘New Harmony’
Survival: 100%
Crown Shape: Vase and round
Lacebug damage to foliage: Significant
European elm flea weevil damage: Minimal
Storm Breakage: Not in Minnesota study
Comments: Narrow, upright habit with strong, central axis
‘Lewis and Clark’ (Prairie Expedition)
Survival: 80%
Crown Shape: Broad oval
Lacebug damage to foliage: Minimal
European elm flea weevil damage: Minimal
Storm Breakage: Good
Comments: Strong grower with broad spreading habit, some wetwood.
Storm damage can be minimized by pruning when the tree is young.
Maintain a central leader but prune out all lower branches as the tree
grows and branches increase in diameter so that there is room to work
under the tree. Also prune out branches attached with a narrow angle as
these are most likely to give way in ice or wind storms. For more
information regarding the study, see
https://webdoc.agsci.colostate.edu/bspm/NationalElmTrial/AUF2017.pdf For
photos and information on hybrids and other species of elm, see
https://webdoc.agsci.colostate.edu/bspm/ElmKansas.pdf .
(Ward Upham)
Start Trees Off Right
Research from K-State’s John C. Pair Horticultural Center has
quantified the effect of controlling grasses around newly planted trees.
Jason Griffin, William Reid, and Dale Bremer conducted a
study to investigate the inhibition of growth of transplanted, seedling
trees when lawn grasses were allowed to grow up to the trunk. There were
five treatments, including three with different
species of grass:
1. Bare soil maintained with herbicides.
2. Area under tree mulched 3 inches deep.
3. Tall fescue allowed to grow under tree.
4. Bermudagrass allowed to grow under tree.
5. Kentucky bluegrass allowed to grow under tree.
All treatments were applied to Eastern redbud seedlings as well as
to pecan seedlings. All trees were fertilized according to
recommendations and watered during the growing season with up to 1 inch
of water if rainfall was deficient. At the end of two years, trees were
measured and harvested. Data was taken on caliper (diameter) 6 inches
above the ground, weight of aboveground portions of the tree, leaf area,
and leaf weight. There were no differences in any measure between the
mulched treatment and the bare soil treatment for either tree species.
All measures showed significant growth increases if lawn grasses were
controlled around the tree.
Results include the following:
1. Caliper: Caliper measures 6 inches above the soil surface were
twice as large for plots
without grass than for those with either fescue or bluegrass, but only
50% larger when compared
to the bermudagrass plots.
2. Top growth weight: Redbuds showed a 300% weight advantage for
plots with
grasses controlled than those without. Pecans showed a significant 200%
increase.
3. Leaf area and leaf weight: Leaf areas were 200% larger in plots
without grass competition
and leaf weight showed a 300% increase.
The obvious conclusion from this study is that grasses must be
controlled under a
newly transplanted tree to get the best possible growth. Though there
were no differences in
growth whether mulch was used or not, you may still wish to mulch for
aesthetic reasons or to
help control weed growth. How far from the trunk should the grasses be
controlled? Try a
minimum of 3 feet. (Ward Upham)
Pawpaw Trees: A Native Fruit
Even though pawpaw is native to eastern Kansas, many people in the
state have never eaten one.
Fruits resemble fat bananas and are generally up to 6 inches long and as
much as 3 inches wide. The taste is unique and is difficult to describe
but is often said to resemble bananas or pineapple and has a texture
somewhat like custard. They are rarely grown commercially because they are
difficult to ship and do not store well. Ripe fruit will only hold 2 to
3 days at room temperature and up to a week under refrigeration.
Pawpaw prefers a well-drained, moderately acid (pH 5.5 to 7.0),
moist soil and high organic
matter content. Organic mulch is also recommended. Irrigation will be
helpful to necessary
depending on what part of Kansas they are grown.
In the wild, the pawpaw is an understory tree and may do better
with partial shade, especially
during the first 2 to 3 years. Protection from high winds is also
advisable due to the large leaves.
The pawpaw is a small tree that may reach 20 feet high but is less
broad. Trees require
cross-pollination and so at least 2 and preferably 3 different varieties
should be grown. These
trees are pollinated by insects other than bees such as beetles and
flies and must be planted close together. Trees should be no further
than 30 feet apart in order to insure good pollination.
The soil for planting should be prepared in advance of receiving
the trees. Amend the soil with
organic matter in the area where the trees will be planted. Do not amend
just the soil from the
planting hole, especially if the soil is heavy and has high clay
content. If you do, you have
essentially made a pot that will hold water and may drown the tree.
Rather add organic matter to
the area in which the tree will be planted before digging the planting
hole; at least a 10- by
10-foot square. You may want to treat the entire area where your trees
will be planted. Add 2
inches of organic matter to the surface of the soil and then till in.
The planting hole should be the same depth as the root system but 2
to 3 times as wide. Pawpaws
have fleshy roots and are better planted in the spring (April) rather
than fall unless container
grown. Container-grown plants can be planted virtually anytime.
Keep newly planted trees well watered. The soil should be moist but
not waterlogged. Keep the
planting area completely free of weeds or any other type of vegetation
within 3 feet of the trees.
Mulching is recommended.
There has been a significant amount of work done on pawpaw by
Kentucky State University.
You can reach their pawpaw site at http://www.pawpaw.kysu.edu/
Information on growing pawpaws is available from Peterson Pawpaws at
http://www.petersonpawpaws.com Neil Peterson’s pawpaws are the result of
over 25 years of research and have been widely tested. Though Neil no
longer sells his varieties directly, he does list a number of nurseries
that carry them.
The Kansas Forest Service (www.kansasforests.org ) has seedling
trees available for sale though
I would recommend getting named varieties instead if you wish to plant
only a few trees. The
fruit from named varieties will be of a higher quality than that from a
seedling tree.
Named variety pawpaws are available from Stark Brothers
(www.starkbros.com ) and Raintree Nursery (www.raintreenursery.com ).
Also check with your local garden center for trees.
The University of Missouri has a couple of different pawpaw
cultivar trials. You can find results
from one of these trials at
http://www.centerforagroforestry.org/pubs/pawpaws.pdf (Ward
Upham)
MISCELLANEOUS
Bird Feeding
Severe winter weather is not only hard on people but can be a life
and death struggle for birds. Though birds also require water and
shelter, food is often the resource most lacking during cold weather.
Many different bird food mixes are available because various species
often prefer different grains. However, there is one seed that has more
universal appeal than any other: black oil sunflower. If you are new to
the bird-feeding game, make sure there is a high percentage of this seed
in your mix. White proso millet is second in popularity and is the
favorite of dark-eyed juncos and other sparrows as well as the
red-winged blackbird.
As you become more interested in bird feeding, you may want to use
more than one feeder
to attract specific species of birds. Following is a list of bird
species with the grains they prefer.
– Cardinal, evening grosbeak and most finch species – sunflower
seeds, all types.
– Rufous-sided towhee – white proso millet.
– Dark-eyed junco – white and red proso millet, canary seed, fine
cracked corn.
– Many sparrow species – white and red proso millet.
– Bluejay – peanut kernels and sunflower seeds of all types.
– Chickadee and tufted titmouse – peanut kernels, oil (black) and
black-striped sunflower
seeds.
– Red-breasted nuthatch – oil (black) and black-striped sunflower
seeds.
– Brown thrasher – hulled and black-striped sunflower seeds.
– Red-winged blackbird – white and red proso millet plus German
(golden) millet
– Mourning dove – oil (black) sunflower seeds, white and red proso
plus German
(golden)millet.
Extended cold periods can also make water unavailable. A heated
birdbath can be a
tremendous draw for birds during times when all other water is frozen.
Energy use is usually less
than what most people expect IF the heater has a built-in thermostat. If
you would like more
information, Chuck Otte, Agriculture and Natural Resources Extension
Agent for Geary County has a series of backyard birding guides at
http://gearycountyextension.com/NRMW.htm (Ward Upham)
Now is a Good Time to Design Your Landscape
The dark, cold days of winter are a good time to dream and plan for
the upcoming growing season. Have you always wanted to landscape your
home but didn’t know where to start? We offer a number of publications
available to help you accomplish your dream. This collection includes
everything from general landscaping publications such as “Residential
Landscape Design,” to specific works such as“Naturalistic Landscaping”
and “Low-Maintenance Landscaping.”
You can download printed publications for landscaping free of
charge from
http://hnr.k-state.edu/extension/publications/landscaping.html .
Information on plants recommended for Kansas can be found at
http://hnr.k-state.edu/extension/info-center/recommended-plants/index.html
You may also request printed copies from your local K-State
Research and Extension office. There may be a small charge for printed
copies of larger publications.
If you need to know how to contact your local extension office, go
to http://www.ksre.ksu.edu/Map.aspx and mouse over your county. (Ward Upham)
Contriubtors: Ward Upham, Extension Associate
