Extension Agent/Stark-Billings County
Horticulture Technician and Extension Intern
Dickinson City Forester
The Horticulture/Forestry Research Plots at the Dickinson Research Extension Center (DREC) have been established in response to an increasing interest from urban and rural audiences. Major research objectives are:
Many new cultivars of trees and shrubs are being developed and released to nurseries for distribution. Some new varieties have many favorable traits for improved hardiness, disease/insect tolerance, vigor and increased ornamental value. This project was established to evaluate performance of some newer cultivars that are currently available under southwest North Dakota growing conditions.
Materials and Methods
Bailey Nurseries, Inc. made this evaluation project possible by donating trees and shrubs for this study at the DREC. Three plants of each cultivar were of the following:
Acer saccharum - "Fall Fiesta™" - Sugar Maple
Aesculus hippocastanum - "European" - Horsechestnut
Fraxinus sp. - "Northern Gem Ash" - Ash
Fraxinus sp. - "Northern Treasure" - Ash
Gleditsia sp. - "Northern Acclaim" - Honeylocust
Malus sp. - "Louisa" - Weeping Crabapple
Tilia mongolica - "Harvest Gold" - Linden
Euonymus sp. - "Prairie Radiance®" - Burning Bush
Ulmus japonica - "Discovery" - Elm
Berberis sp. - "Emerald Carousel" - Barberry
Berberis sp. - "Golden Carousel" - Barberry
Cornus alba - "Ivory Halo" - Dogwood
Exchorda serratifolia - "Northern Pearls" - Pearlbush
Philadephus Lewisii - "Blizzard" - Mockorange
Potentilla fruticosa - "Dakota Goldrush®" - Potentilla
Potentilla fruticosa - "Dakota Sunspot®" - Potentilla
Salix purpurea - "Gracilis" - Willow
Spirea japonica - "Dakota Goldcharm®" - Spirea
Syringa sp. - "Tinkerbelle" - Tree Lilac
All trees were bare root stock and were planted on May 4, 2001. Planting holes were dug with a tractor mounted post hole digger and planted by hand. Soils ranged from a sandy loam to a heavy clay. All trees were watered after planting and received supplemental water when needed. A 2-3' circular flax blanket was applied to the base of each tree for weed control and improved water efficiency. No fertilizers were applied.
All shrubs were also bare root stock. They were hand planted on May 30, 2001. Prior to planting treflan granules were applied for weed control. Shrubs were watered on an as needed basis.
Results and Discussion
Trees and shrubs were evaluated throughout the growing season. Official evaluations were conducted on July 20, 2001; October 5, 2001, and November 15, 2001.
Tree evaluations: Characteristics evaluated included: response to transplanting, leaf emergence, new growth, leaf and bark color, disease and insect tolerance, overall vigor and ornamental value. Preliminary observations are as follows:
All three specimens transplanted well. August - terminal growth was 5¾" with a lateral growth averaging 4". This cultivar has several favorable characteristics: medium green leaf color with dramatic red fall color. Leaves remained on the tree late into the fall, still present on November 15, 2001. This tree has a unique light tan to brown bark color and is rated very good for ornamental value and overall vigor.
This cultivar ranks high in overall vigor with average terminal growth of 12¼", and lateral growth of 6¼". Pink flowers, weeping growth habit, attractive dark brown bark color and small red berries contribute to ornamental value of this variety. Specimens were in an extremely healthy condition this fall.
Average terminal growth was 13" and lateral growth was 8". One specimen had an outstanding terminal growth of 21½" and average lateral branch growth of 8". Leaf emerge was good with attractive leaflet arrangement with yellow fall color. Overall vigor is very good. Some evidence of aphid leaf injury.
Overall vigor is good with terminal branch growth average of 12" and lateral of 9". Some tip dieback on one tree and another was planted too deep. Leaf color is a light yellow to green with yellow fall color. Black leaf buds are a unique characteristic.
Two of the three specimens survived. However, these trees are in a very stressed condition with up to 2' of branch tip dieback. Emerged leaves were small and green in color.
Leaves of this are very attractive, with deep veins and medium to dark green in color. Terminal branch growth averaged 9½" but lateral development was less than 1". One tree didn't survive, but it was planted too deep in a heavy, poorly drained, clay soil.
This cultivar has some interesting ornamental value: tree form growth habit, light green leaf color and grayish green bark color. Terminal growth was 2½" and lateral growth of 1¼". All trees appeared to be in a thrifty condition this fall.
All three trees of this cultivar suffered from transplant shock and not enough moisture when being established. Two of the three trees appear to be dead, and the other has serious branch dieback.
All three specimens survived the first year, but some branch dieback was observed. Average terminal branch growth was 7" with a very limited lateral growth--less than 2". Light green leaf color, leaf arrangement and dark green bark are interesting characteristics of this cultivar.
Formal evaluations were conducted on July 20, 2001, and October 5, 2001. Observations included leaf emergence, leaf color, bloom impact, overall vigor and ornamental value.
Small compact shrubs with a desirable mounding growth form. Leaf emergence was good and color was a dark green. No blooms this year. Overall vigor was rated very good.
Attractive foliage is a unique characteristic of this variety. Leaf color ranges from a bright yellow to a dramatic yellow/red in the fall. This shrub is rated good for overall vigor and has high potential overall ornamental value.
Variegated leaves, light green with dramatic white margins were very attractive. Brilliant red bark adds additional ornamental interest. Two of the three shrubs had very good overall vigor while the other specimen had some dried leaves this fall.
All three plants suffered initially from transplanting; however, two recovered nicely by the time of fall evaluation. Light green leaves turned to a grey/light green color in the fall. One shrub bloomed this year with pretty white flowers.
This was one of the highest rated shrubs in our evaluation project. Overall vigor was outstanding. Ornamental value is enhanced by the bright green leaf color and compact growth form. A limited number of blooms were present during the first evaluation. Bloom value was greatly improved with a multitude of bright yellow flowers this fall. First year performance was very impressive.
Compact form and yellow/green foliage were the most attractive features of this shrub. Pink blooms were limited this first year. Two of the specimens showed good overall vigor while the third had more limited development.
This cultivar performed very good. One of the three shrubs was superior for overall vigor and growth and had a multitude of bright yellow flowers this fall. Leaf color is an attractive dark green. This shrub has a compact growth form which means it can be utilized in diversified landscape plantings.
This shrub established nicely. Overall vigor was very good during the year. Special features are blue/green leaves and purple/red bark color. A rounded spreading growth could add additional interest in informal/naturistic plantings.
Leaf color ranged from a yellow/green in the summer to a tan/green in the fall. Bloom color is a distinctive bright pink. This cultivar gets a high rating for overall vigor and ornamental value. Compact mound growth form is very desirable for many different formal landscape plantings.
Overall vigor and development of this cultivar was very good. Leaves are heart-shaped and light green in color. Flowering was very limited this first year; however, blooms have an enthusiastic pink color. Has potential for many different landscape uses.
Of the three shrubs planted, one appears very healthy, one is dead, and the other is questionable. No flowers this year. Leaf color is light green.
Overall performance of trees and shrubs planted in this evaluation project was quite good. However, the real test will be how well they survived our southwestern North Dakota winter conditions. Evaluation will continue in 2002.
The diversity of planting materials has already served an educational function. This evaluation project was showcased during the annual DREC horticulture tour, the North Dakota State Horticulture Society Conference, and was viewed by hundreds of DREC visitors.
Thank you to Kris Ringwall, DREC director, and staff for all the cooperation and assistance with planting, care and maintenance of trees and shrubs.
A special thank you to Jim Stolzenburg, Baily Nurseries, Inc., St. Paul, Minnesota.