Landscaping - Tough Trees by jkudoro


                  Tough Trees
                  for Wyoming
                          Karen L Panter
                      University of Wyoming
                  Extension Horticulture Specialist
                   Department of Plant Sciences

                          Emily E. Ewart
                      University of Wyoming
                    Graduate Research Assistant
                    Department of Plant Sciences

Diana Marie Hill-Chavez

David W. Wilson
        During the late 1970s and early 1980s, numerous deciduous trees and shrubs were
planted at the University of Wyoming Research and Extension Centers throughout the
state. The sites were at Torrington, Powell, and the College of Agriculture greenhouse
complex on the UW campus in Laramie.
        The trees and shrubs were cared for during the decade of the 1980s, but since then
have been on their own. Fortunately, extensive records of the plantings and their care
exist. We were able to evaluate the remaining trees and shrubs at each site during fall
1998. Using the historical maps and written records of the sites, the trees and shrubs were
checked for survival and general condition, if they were still alive at all.
From 1977 to 1988
        Watering, fertilization, and pruning records are somewhat sketchy but usable. In
the bottom of each planting hole, almost without exception, the planters placed one or
two “planting pills,” listed in some of the notes as Agriform from the Sierra Company (no
longer in existence). This practice is no longer recommended.
        A few references to watering practices after the trees were planted are available.
In Laramie, a drip irrigation system was set up for the plants. Furrow irrigation of the
trees and shrubs after planting was done in Powell; we assume this practice continued.
The plants at all sites were watered in after planting, but specific details are not included
in the records.
        Fertilization occurred periodically, usually by foliar feed of iron (Sequestrene
138) on specific chlorotic plants. Manure was applied at Powell. Pruning dead or disease-
or insect-damaged limbs was done at least annually. Those plants that tended to send up
suckers were pruned off periodically.

From 1988 to 1998
        During the ten years that elapsed after the date the last records were written
(1988), the trees and shrubs at the three sites received virtually no care. Watering was
done sporadically, if at all. Fertilization and pruning were virtually nonexistent practices.
As a result, only the fittest trees and shrubs survived.
        The harshest climate of the three planting sites is Laramie. The wettest of the
three sites is Torrington. Powell has the longest growing season but the least amount of
annual precipitation (Table 1).

       Fall color on green ash
       Fraxinus pennsylvanica ‘Cardan.’


Table 1. Elevations, average growing season lengths, and annual precipitation at three
sites in Wyoming used for tree and shrub plantings.

          Site       Elevation         Growing Season            Annual Precipitation
      Laramie          7,165       June 9 to September 10                11"
      Powell           4,365       May 10 to September 26                 7"
      Torrington       4,104       May 17 to September 17                13"

        For those Wyoming residents, whether new or established, interested in woody
plants that will survive in this climate with little or no extra care, the findings of the 1998
evaluations should provide useful information (Table 2).

Table 2. Deciduous trees and shrubs that survived at all three planting locations in
Wyoming with little to no care.

                                      Percent         Percent         Percent
                                      Survival        Survival        Survival        Date
            Species                   Laramie          Powell        Torrington      Planted
Fraxinus pennsylvanica
‘Cardan’ - Cardan green ash               66             100              33           5/80
Malus ‘Radiant’ – Radiant
crabapple                                 33             33               33           5/80
Malus ‘Royalty’ – Royalty
crabapple                                 33             66               50           5/80
Malus ‘Spring Snow’ – Spring
Snow crabapple                            66             66               33           5/80

        The common characteristics of the species that survived at all locations are their
toughness and their ability to adapt to varying climatic conditions (Table 2). The plants in
Table 3 display varying degrees of adaptability. For example, Kentucky coffeetrees
survived well in Torrington but nowhere else, while the Patmore green ash survived in
Laramie and Powell but not in Torrington. The reasons for these phenomena are unclear
but indicate that without added attention after establishment, many of the trees and shrubs
in Table 3 will not survive. Those plants in Table 4 are among the most difficult to grow
successfully in the Wyoming climate.


Table 3. Deciduous trees and shrubs that survived in at least one of three planting
locations in Wyoming with little to no care.

                                     Percent     Percent      Percent
                                     Survival    Survival     Survival      Date
               Species               Laramie      Powell     Torrington    Planted
Acer ginnala ‘Flame’ – Flame amur
maple                                  33           66           0          6/83
Cercocarpus montanus – Mountain
mahogany                               100          0            0          5/83
Eleagnus commutata - Silverberry        66          0            0          5/83
Euonymus europaeus ‘Redcap’ –
Redcap euonymus                         0           0           100         4/81
Fraxinus pennsylvanica ‘Patmore’ -
Patmore green ash                      100          66           0          5/84
Gymnocladus dioicus -Kentucky
coffeetree                              0           0           100         5/81
Lonicera alpigena – Alps
honeysuckle                             0          100       Not planted    8/87
Lonicera chrysantha villosa -
Honeysuckle                             0           66       Not planted    8/87
Lonicera korolkowii v. floribunda
‘Blue Velvet’ – Blue velvet                         Not                     5/83,
honeysuckle                            100        planted    Not planted    8/87
Lonicera muendeniensis -                            Not
Honeysuckle                            33         planted    Not planted    7/88
Lonicera prolifera -Honeysuckle         0           50       Not planted    7/88
Lonicera tatarica ‘Lutea’ –                         Not
Tatarian honeysuckle                   33         planted    Not planted    8/87
Lonicera x xylosteoides -
Honeysuckle                            25          100       Not planted    8/87
Lonicera xylosteum – European fly
honeysuckle                             0           66       Not planted    7/88
Malus ‘Barbara Ann’ – Barbara
Ann crabapple                           0           0            33         5/82
Malus ‘Candied Apple’ – Candied
Apple crabapple                        33           0            33         5/82
Malus ‘Centurion’ – Centurion                                     0
crabapple                              66           0                       5/84
Malus ‘Donald Wyman’ – Donald
Wyman crabapple                        33          100           0          5/80
Malus ‘Eleyi’ – Eleyi crabapple         0           66           0          5/80
Malus ‘Inglis’ – Inglis crabapple       0          100           0          5/80
Malus ‘Katherine’ – Katherine
crabapple                               0           0            33         5/82

Malus ‘Prof. Sprenger’ – Prof.
Sprenger crabapple                       0           33            0          5/84
Malus ‘Profusion’ – Profusion
crabapple                               33            0            0          5/84
Malus ‘Selkirk’ – Selkirk crabapple     33            0           100         5/82
Malus baccata mandshurica
‘Midwest’ – Midwest crabapple           66            0            0          5/83
Populus ‘Imperial’ – Imperial                        Not
cottonwood                               50        planted         0          6/83
Rosa rubrifolia – Redleaf rose          100           0           66          5/83
Syringa reticulata -Japanese tree
lilac                                   33            0           33          6/81

Table 4. Deciduous trees and shrubs that did not survive at any of the three planting
locations in Wyoming or were not planted at one or more location. Locations were
Laramie, Powell, and Torrington.

                     Species                    Location(s) Planted     Date Planted
Betula platyphylla var. japonica - Japanese
white birch                                           Laramie              5/85
Cretaegus chrysocarpa – Fireberry hawthorn            All three            5/83
Laryx PI 368110 - Larch                               Laramie              6/81
Lonicera coerulea - Honeysuckle                       Laramie              7/88
Lonicera heteroloba - Honeysuckle                     Laramie              8/87
Lonicera pyrenaica - Honeysuckle                      Laramie              7/88
Lonicera xylosteum lutea - Honeysuckle                Laramie              8/87
Malus ‘Henningi’ – Henningi crabapple                 All three            5/84
Malus ‘Indian Magic’ – Indian Magic crabapple         All three            5/82
Malus ‘Liset’ – Liset crabapple                       All three            5/84
Malus ‘Robinson’ – Robinson crabapple                 All three            5/84
Malus sargenti ‘Tina’ – Tina crabapple                All three            5/80
Populus deltoides ‘Siouxland’ – Siouxland
cottonwood                                           Laramie               5/80
Populus hybrid #310 - Cottonwood                Laramie, Torrington        4/81
Populus hybrid #508 - Cottonwood                Laramie, Torrington        4/81
Prunus mackii – Amur chokecherry                     All three             5/82
Pyrus calleryana ‘Bradford’ - Bradford pear          All three             4/81


         Commercial availability of the plants in Tables 2 and 3 should be noted. Of those
listed in Table 2, ‘Cardan’ green ash may not be readily available from regional nurseries,
although many other species of Fraxinus pennsylvanica are, including ‘Patmore.’
‘Radiant’ and ‘Spring Snow’ crabapples are both quite sturdy and are readily available.
These varieties are relatively resistant to fireblight, but ‘Radiant’ is extremely susceptible
to apple scab. ‘Royalty’ crabapple is not available in the region, probably due to its
extreme susceptibility to both fireblight and scab.
         Many of the plants listed in Table 3 are not available commercially. Some of
these include Lonicera alpigena, Lonicera chrysantha villosa, Lonicera muendeniensis,
and Lonicera prolifera. Often Lonicera xylosteum and Lonicera x xylosteoides are
synonymous; the variety commonly available currently is ‘Emerald Mound.’
         Several crabapple species are listed in Table 3. ‘Barbara Ann,’ ‘Candied Apple,’
‘Donald Wyman,’ ‘Eleyi,’ ‘Inglis,’ ‘Katherine,’ ‘Prof. Sprenger,’ ‘Selkirk,’ and
‘Midwest’ could not be found in the region commercially. The reasons are due to either
hardiness problems or disease susceptibility or both. The only other species listed in
Table 3 that could not be found in the region is Populus ‘Imperial.’
         Residents who would like to try some of the plants listed in Table 4 should be
prepared to water a great deal for these plants to survive. Many of these plants are readily
available from regional nurseries including Betula platyphylla var. japonica, Lonicera
xylosteum, Malus ‘Indian Magic,’ Malus sargenti, Populus deltoides ‘Siouxland,’ Prunus
mackii, and Pyrus calleryana. The variety listed with the latter, ‘Bradford Pear,’ has been
replaced by other superior varieties that can be found regionally. Often, newer varieties
are bred or selected to replace older varieties of the same species.

                              Malus spp. (crabapple) in the fall.

         The University of Wyoming and United States Department of Agriculture cooperating.
                 The University is an equal opportunity/affirmative action institution.


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