University of Arkansas Plant Evaluation Program

2003 Plants/ Arkansas Plant Evaluation Program2004 Final Report

[Program information (data, reports, photographs) can be found on the internet at: http://www.uark.edu/campus-resources/cotinus/arboretum_html/planteval.html]

2004 Final Report

January 2005

 

Plants initiated in Spring 2003:

 

This completes the sixth year of the statewide plant evaluation program.  The current team of cooperators includes Dr. Jim Robbins, Dr. Jon Lindstrom, and Manjula Carter.

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 November 19; Fayetteville on November 16; and Hope on November 28.

Weather data at all three test sites is attached (see attached graph). 

 

Heptacodium miconioides

One-gal plants were initiated from UofA seed.  Plants grew exceptionally well statewide with no mortality after two growing seasons.  Plants flowered at all three locations. At Hope, flowering began in mid-August and last for nearly two months.  In Fayetteville, flowering commenced early, July 30th, and continued until the middle of August. The red calyx remained ornamental into mid October. Average plant size is 73” tall x 70” wide with a mean growth index (GI) of 4.509 m3.

 

Sinojackia xylocarpa

One-gal plants were initiated by UofA 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 is 69” tall x 36” wide with a mean growth index (GI) of 1.428 m3.

 

Thuja plicata ‘Green Splendor’ (‘Hoyt’)

One-gal plants of ‘Hoyt’ were initiated by cuttings at UofA 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 44” tall x 22” wide with a mean growth index (GI) of 0.317 m3.

 

Cephalotaxus harringtonia  ‘Prostrata’

One quart plants were initiated by cuttings at UofA from Univ. 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.

 

Deutzia setchuenensis v. corymbiflora

One quart plants were initiated by cuttings at UofA from Heronswood Nursery plants.  After losing all four plants at Hope in 2003, we now have lost all four plants at Little Rock in 2004.  Average plant size at Fayetteville is 39” tall x 41” wide. Plants in Fayetteville began to flower in mid May and continued through August.

 

Calocedrus decurrens

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.  All 4 plants are now dead at Hope and three of the four at Little Rock are now dead. Average plant size on the remaining plants is 14” tall x 8” wide. Three plants are still alive in Fayetteville and one of these is significantly larger than the remaining trees.

 

Acer saccharum  ‘John Pair’

Five foot bareroot whips were donated by J. Frank Schmidt Nursery.  Plants are struggling in 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 only one tree remains in the trial at Little Rock. All trees are alive in Fayetteville. Mean shoot height on remaining trees is 100 inches with a trunk caliper at 39 inches of 0.9”.

 

Acer saccharum  ‘Autumn Splendor’

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 are now dead at Little Rock.  Mean shoot height on remaining trees is 119 inches with a trunk caliper at 39 inches of 1.1”.

 

 

 

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.