University of Arkansas Plant Evaluation Program
2003 Final Report
Plants initiated in Spring 2003 (5 years data):
This completes the ninth year of the statewide plant evaluation program. The current team of cooperators includes Dr. Jim Robbins, Dr. Jon Lindstrom, and Qingfang Chen.
The three test sites are the Hope Research Center (USDA cold hardiness zone 8), the Little Rock/Cooperative Extension Service property (zone 7a), and the Fayetteville Horticulture Research farm (zone 6b). As much as possible the three test sites were prepared in a similar manner. Full sun plants were grown in row-type beds 3' wide with a 7' grass alley. Plant groups are planted together (i.e. trees are planted together). Trees are spaced 10' apart, shrubs 6' apart, and herbaceous perennials 4' apart. The Little Rock site was planted on March 14, 2003; Fayetteville was planted on March 10, 2003; Hope planted on March 14, 2003. Irrigation at all three sites is by a drip system. Plants were fertilized and mulched after planting. Post-emergent herbicides were used at all three test sites. No disease or insect control was implemented during the first year. To maintain a tree-like habit, trees are pruned following final growth measurements. Pruning consists of removing the bottom 1/3 of limbs. SHRUBS are NOT pruned. Final growth measurements were taken at Little Rock on October 9; Fayetteville on November 27; and Hope on November 13.
The spring 2007 was marked by a historic and devastating statewide freeze on Easter weekend that must have influenced some plants in these trials.
|Rating||(growth after 5 years)|
|Thuja plicata 'Hoyt'||3||80||39|
|Cephalotaxus harringtonia 'Prostrata' [NO PICTURE]||CJ||-||-|
|Deutzia setchuenensis v. corymbiflora [NO PICTURE]||6||60||54|
|Acer saccharum 'John Pair'||6||170||3|
|Acer saccharum 'Autumn Splendor'||6||154||2.7|
CJ = cannot judge due to insufficient information or other reasons
1 = Plant has performed well statewide
2 = Plant has performed well in zones 7a and 8.
3 = Plant performed fair statewide
4 = Plant performed fair zones 7a & 8
5 = Plant not recommended
6 = Plant performed well in 6b, poor in 7a & 8
7 = Plant performed fair in 6b, poor in 7a & 8
One-gal plants were initiated from U of A seed. Plants grew exceptionally well statewide with no mortality after five growing seasons. All 12 plants are still alive. Plants flowered at all three locations. At Hope, flowering began in mid-August and lasted until the end of September. The red calyx remained ornamental into mid October. Average plant size statewide is 116" tall x 110" wide with a mean growth index (GI) of 18.888 m3. We have not seen any evidence of self-sown seedlings in the plots. Heptacodium seed takes one year to germinate when sown after fall collection.
One-gal plants were initiated by U of A from an Arborvillage plant. Three of four plants at Fayetteville died during 2004, the remaining plant flowered in late April. Plants are growing well at Little Rock and Hope. Plants flowered at all three locations in 2004. Flowering starts in early April and lasts for about two weeks. Average plant size statewide is 104" tall x 68" wide with a mean growth index (GI) of 7.373 m3. In general, plants are doing better in zones 7 and 8 than zone 6.
One-gal plants of 'Hoyt' were initiated by cuttings at U of A from Univ. of Georgia plants. The cultivar name has changed to 'Green Splendor'. Plant mortality was very high during the 2004 growing season at Little Rock with all four plants dying. The plants were likely killed in early summer due to heavy rainfall. Pythium/Phytophthora was confirmed on roots of plants. Average plant size on remaining plants statewide is 80" tall x 392" wide with a mean growth index (GI) of 1.855 m3. 'Hoyt' is clearly not as aggressive a grower as T. x 'Green Giant'.
One quart plants were initiated by cuttings at U of A from University of Georgia plants. Nine of the 11 original plants died in 2003 and the remaining plants died in 2004. We suspect that the high mortality is due more as a result of the very small plants we started with than the adaptability of this plant to Arkansas conditions.
One quart plants were initiated by cuttings at U of A from Heronswood Nursery plants. After losing all four plants at Hope in 2003, we lost all four plants at Little Rock in 2004. Average plant size at Fayetteville after five years is 60" tall x 54" wide. Plants in Fayetteville began to flower in mid May and continued through August. Fayetteville plants have been killed to the ground in some winters and this species may be more suitable in slightly warmer areas.
Five foot bareroot whips were donated by J. Frank Schmidt Nursery. Plants struggled at Little Rock and Hope. At these two locations trees suffered shoot dieback. Again, we tend to see significant plant loss when dealing with BR trees. All three trees died at Hope during 2004 and the one remaining tree in Little Rock died during 2007. All trees are alive in Fayetteville. Attractive orange/red (distinctively more red than 'Autumn Splendor') fall color was noted on this selection at Fayetteville in 2006. Mean shoot height on remaining trees in Fayetteville is 170" with a trunk caliper at 6 inches of 3.0".
Six foot bareroot whips were donated by J. Frank Schmidt Nursery. This clone performed slightly better than 'John Pair' with less shoot dieback at the 3 locations. All three trees died at Little Rock. Attractive orange fall color was noted in Fayetteville in 2006. The growth habit between these two cultivars is noticeably different at this age. 'John Pair' has a more dense, upright oval habit whereas 'Autumn Splendor' is a more open upright oval. Mean shoot height on remaining trees is 154" with a trunk caliper at 6 inches of 2.7".
Two foot tree tubes were purchased from Forestfarm Nursery. In 2003 we reported that the “Plant is performing well statewide which is amazing considering how small these plants were at the start". The small plant size may have caught up with us. Ten of the 12 plants had died within the first three years. Plant size on the sole remaining plant at Fayetteville is 14" tall x 7.9" wide. The single remaining plant in Fayetteville is an impressive specimen, growing well in an exposed location.
The Ornamentals team would like to express their sincere appreciation to the cooperating nurseries (J. Frank Schmidt Nurseries, Dr. Michael Dirr- University of Georgia) for donating the plants for this season's trial and to the Arkansas Green Industry Association for financial support.