University of Arkansas Plant Evaluation Program

2001 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 2001:

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. Plants 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 23, 2001; Fayetteville was planted on March 23, 2001; Hope planted on March 22, 2001. 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).

Agarista populifolia Leprechaun^TM

Flowerwood Nursery donated 3-gal plants. Performance appears to be good at Hope. All three plants are now dead at Little Rock. The plants are declining in Fayetteville. Flowers were first noted in early May and continued for about 1 week at Hope. Flowering occurred in early May in Fayetteville. Average plant size statewide is 30” tall by 39” wide with a growth index of 0.778 m³. Average plant height at Hope, which is probably more typical, is 39” with a width of 52”.

Gelsemium sempervirens Lemon Drop^TM

Flowerwood Nursery donated 1-gal plants. All plants are dead statewide. Little Rock lost two of the three plants in 2002. Hope lost all plants that summer also.

Pyrus fauriei Korean Sun^TM

J. Frank Schmidt Nursery donated 4’ BR plants. So far, the plant is performing fair to poor at all three locations. Habit is more like a crabapple and foliage is thin. In Fayetteville, the trees begin to flower in late March (when P. calleryana is at peak) and then set a significant amount of fruit. Foliage that remains healthy at the end of the season has a nice deep maroon fall color. Average tree height statewide is 66” tall with a trunk caliper (@ 6”) of 1.8”.

Itea ilicifolia

University of Arkansas propagated plants and they were planted from a 1-quart container. All of the nine original plants are now dead. The oak-like foliage is very attractive. Emerging foliage is a beautiful copper color.

Itea oldhamii

University of Arkansas propagated plants and they were planted from a 1-quart container. All plants at Hope and Fayetteville are dead. The plants in LR flower with a peak around mid-March. Flowers are actually quite impressive. The white spikes are shorter than Itea virginica but still showy. Average size in LR is 43” tall x 44” wide.

Crataegus species

University of Arkansas seed-propagated plants from a stock plant at Blossomberry Nursery in Clarksville, AR. This plant is from a 1970’s distribution from the U.S. National Arboretum. At this time we have no further information on its identity. Trees were planted as a 1-gal container plant.

The plant continues to grow very well at all three sites. Not a single plant has died statewide. Plants began to flower in 2003. Flowering occurs in mid-April and lasts, depending on location, from one to two weeks. The fruits are very attractive, 1/3”, yellow color. The fruiting display in 2004 in Fayetteville was not ornamental, many fruit did not ripen due to late season heat and drought. In September, in Little Rock and Hope, a significant number of leaves were affected by some type of leaf spot disease. Statewide tree height is 114” with an average trunk caliper (@ 6”) of 3.8”.

Quercus × Crimson Spire^TM

J.Frank Schmidt Nursery donated 3’ BR whips. Trees are growing well at all three test sites. Fall color was almost non-existent at all three sites. Some large acorns were noted at Fayetteville. In size they resemble the fastigiate English oak parent. Although powdery mildew appeared in Fayetteville, it was 95% less than fastigiate English oak. Statewide tree height is 130” with a trunk caliper (@ 6”) of 2.9”.

Deutzia setchuenensis var. corymbiflora

University of Arkansas propagated plants and they were planted from a 1-quart container. Sadly, all three test plants were stolen from the Little Rock site when this plant was in full flower.

We are still very impressed with the length of flowering on this shrub. Plants at Hope starting flowering in late April and until early November. Plants in Fayetteville begin to flower in mid May and continue to frost. We don’t expect that this extended bloom time will continue on mature plants. The source plant on the University of Arkansas campus (now mature) flowers once in late May and no repeat bloom occurs. Due to the fact the three plants were stolen in Little Rock and some over-ambitious Roundup spraying in Fayetteville, we re-evaluated this plant in 2003.

Average plant size statewide is 42” tall by 40” wide.

Viburnum utile

University of Arkansas propagated plants and they were planted from a 1-quart container. Performance of this broadleaf evergreen is good at all three sites. Plants began to flower at all three locations in 2003. Flowering is in mid-April and lasts for about 2 weeks. Average plant size statewide is 39” tall by 72” wide.

Fontanesis fortunei ‘Titan’

University of Arkansas propagated plants and they were planted from a 1-quart container. Growth rate is unbelievable at all three sites. Flowering is typically in early to late April. Flowers are slightly showy. Average plant size statewide is 114” tall by 103” wide. This plant might make a good screen but the amount of seed produced is of some concern.

Thuja × ‘Green Giant’

The Botany Shop, Joplin, MO, donated 1-gal plants. Performance was outstanding at Hope and Fayetteville, however, one plant died at Little Rock from what was identified as Pythium/Phytophthora following a wet spring. Bagworms were observed on plants at all three locations. Average plant size statewide is 104” tall by 57” wide.

Acer negundo ‘Sensation’

J. Frank Schmidt Nursery donated 7’ BR whips. Growth was fair at all three sites. Foliage at all three sites was less than attractive. Leaves are just severely distorted in June by leafhoppers. Foliage that developed later in the season displayed less of this leaf distortion. Plants exhibited no fall color. Average tree height is 146” with an average trunk caliper (@ 6”) of 3.4”.

Cotinus obovatus

J.Frank Schmidt Nursery donated 1-gal plants. All but one of the American smoketrees are dead. It would appear that our intense summer heat is too hard on this outstanding plant when grown in full sun.

Agapanthus ‘Headbourne Hybrids’

One quart plants were purchased from Colvos Creek Nursery, WA. Plants are performing fair at Little Rock and Hope. Plants in Fayetteville are multiplying nicely and began flowering in late June and continues for a month. Plants at Hope and LR begin flowering the second week of June and flower for at least one month.

The Ornamentals team would like to express their sincere appreciation to the cooperating nurseries (Flowerwood Nurseries, J. Frank Schmidt Nursery, and The Botany Shop) for donating the plants for this season’s trial and to the Arkansas Green Industry Association for financial support.