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Charles R. Hall and Dewayne Ingram

, positive impact on atmospheric GHG. The life cycle GWP of the described redbud tree, including GHG emissions during production, transport, transplanting, take-down, and disposal, would be a negative 63 kg CO 2 e ( Ingram et al., 2012 ). These data can be

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Len Burkhart and Martin Meyer Jr.

Selected cultivars of redbud (Cercis canadensis L.) and related Cercis species are usually propagated by grafting, but the success rate is low and other problems can be associated with the rootstock. Micropropagation would solve many of these problems. Shoots from a 25 year-old redbud were collected during July 1989 and established in vitro on modified MS medium. Shoots proliferated poorly with lower concentrations of Benzyladenine (BA) and high concentrations of BA caused shoot tip abortion. Similar problems with red-silver hybrid maples were solved by the use of Thidiazuron (TZ) in the medium. Established 2 cm redbud shoots were treated with TZ (0, 0.05, and 0.1 uM) and BA (0, 1 and 5 uM) in a factorial arrangement to test for shoot proliferation. After 4 weeks of the treatment with 0.1 uM TZ and 5 uM BA, mean shoot number was 4.6 compared to 1.1 shoots with no BA or TZ in the medium. Further experiments with rooting treatments will be presented.

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A.M. Shirazi and K.A. Jacobs

Near-lethal abiotic stresses, e.g., low or high temperatures, chemicals, etc., can break endodormancy prematurely and reduce cold hardiness in woody plants. It is not well-ducumented whether biotic stresses can cause the same effect. Botryosphaeria dothidea causes canker in redbud (Cercis canadensis) and many other woody plants and is one of the most limiting factors growing redbud in the landscape. Two-year-old seedlings were planted in a nursery in May 1998 at The Morton Arboretum. Trees were inoculated (n = 10/treatment) with the fungus in Sept. 1998 using the stem slit method (a slit was cut about 5 cm above the base of the trunk and the wound was covered with parafilm after treatment). The treatments were T1 = control (PDA, Potato Dextrose Agar),T2 = 1-mm mycelium plug, T3 = low spore suspension (25 μL), T4 = high spore suspension (25 μL). Stem cold hardiness was evaluated by artificial freezing tests in Nov. 1998. The mean LT50 (the temperature at which 50% of the tissues is killed) from ion leakage were T1 (Control) = -29.3 °C, T2 (mycelium): -24.05 °C, T3 (low spore) = -18.75 °C, and T4 (high) = -16.4 °C. T3 and T4, the low- and high-spore inoculation, significantly reduced cold hardiness in redbud stem tissues. The LST (lowest survival temperature) based on visual observation of the samples after 7 days indicated all Botryosphaeria dothidea-treated plants had lower cold hardiness compared to control. Endodormancy was broken in B. dothidea-treated plants after placing plants under 16 h of light and 23 /18 °C day/night temperature for 1 month after the treatment. The highest percent budbrealk was for T4 (high spore), followed by T3 (Low Spore) and T2 (Mycelium).

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Richard A. Jaynes

Abstract

Many unusual forms of mountain laurel are under simple genetic control. Myrtifolia (m) and polypetala (p) appear to be controlled by single recessive genes. Two types of banding on the inside of the corolla, fuscata (B) and star-ring (Sr), are apparently controlled by single dominant genes: a recessive lethal trait for albino seedlings occurred among some of the banded crosses. Flower color inheritance is complex. True breeding red-budded or white flowered seedlings have been secured, and true breeding pinks appear possible. Red-bud is recessive to white and wild type.

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D. F. Hamilton and P. L. Carpenter

Abstract

An examination of dormancy in seeds of Eastern Redbud, Cercis canadensis L., showed that dormancy is controlled by permeability of the testa. Scarification by H2SO4 or mechanical abrasion permitted rapid and complete germination of dormant seed. Stratification was necessary only if seed were not scarified. Nonscarified seeds showed almost no water uptake during 55 days at 5°C, while scarified seeds had a steep imbibitional gradient. Germination was not stimulated by adding oxygen. No growth inhibitors were detected in dormant seed, and no promoters were found in chilled seeds.

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Jason J. Griffin, William R. Reid, and Dale Bremer

Successful establishment and growth of newly planted trees in the landscape is dependent on many factors. Weed pressure and water conservation are typically achieved with either organic mulches or chemical herbicides applied over the root ball of the newly planted tree. In the landscape, eliminating turfgrass from the root zone of trees may be more complicated than resource competition. Studies have shown that tall fescue (Festucaarundinaceae Schreb.) has allelopathic properties on pecan trees [Caryaillinoiensis (Wangenh.) K. Koch]. Well-manicured tall fescue turf in the landscape may have negative effects on the establishment and growth of landscape trees as well. A study was designed to examine the effects of popular turfgrasses on the growth of newly planted pecan and redbud (Cerciscanadensis L.). Results demonstrate that the presence of turfgrass over the root zone of trees negatively impacts tree growth. Through two growing seasons, every growth parameter measured on redbuds (caliper, height, shoot growth, shoot dry weight, root dry weight, leaf area, and leaf weight) was significantly reduced by the presence of turf. However, the warm season bermudagrass [Cynodondactylon (L.) Pers.] was less inhibitied than the cool season grasses. The affects of turfgrass on pecan growth was less significant; however, caliper, leaf area, and root dry weight were significantly reduced when grown with turf.

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Michael R. Spafford and Gary J. Kling

Cercis canadensis, Eastern Redbud, is very Cercis canadensis, Eastern Redbud, is very susceptible to infection by Verticillium Wilt caused bysusceotible to infection by Verticillium Wilt caused by the common soil-borne fungi Verticillium albo-atrum and Verticillium dahliae. Little is known about the inoculum levels, the time required for natural infection to occur and how fast the pathogen travels inside the host species. One-year-old Cercis canadensis seedlings were planted in 7.6 liter (2-gallon) containers with a 1:1:2 soil/sand/perlite mix inoculated with five levels (0, 10, 100, 500, and 1000 microsclerotia/g soil) of V. dahliae prior to planting. At the end of the first growing season, half of the plants were removed from the containers, surface sterilized, dissected and root sections plated out on a Verticillium selective media. The remaining plants were grown for a second season. Infection first occurred in plants which received 100, 500 or 1000 ms/g at the end of the first season. The infection had spread at least 5 cm during the first growing season.

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Dan Neely and W. R. Crowley Jr.

Abstract

Seventeen commercial products containing 11 herbicides used to control weeds in lawns were tested at rates recommended by the manufacturers and at three times the recommended rate in plots of established white ash and pin oak trees for three consecutive seasons. Bandane, benefin, bensulide, 2,4-D, DCPA, DSMA, siduron, silvex, 2,4,5-T, and trifluralin were not phytotoxic but dicamba consistently caused phytotoxic symptoms especially at the high dosage. Tree species sensitivity to dicamba varied with rate of application, soil type, and amount of rainfall. White and blue spruce trees were readily killed; tulip trees, honey locust, pin oak, and linden trees suffered twig die back; walnut, ash, maple, and redbud trees suffered leaf distortion and red cedar trees were unaffected.

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Hala G. Zahreddine, Daniel K. Struve, and Salma N. Talhouk

The Mediterranean region is a center of great plant diversity, harboring around 25,000 plant species, more than 20% of them endemic. Since the last Lebanese flora record in 1966, the country has experienced habitat fragmentation and destruction, due to overgrazing, overexploitation of natural resources, and urban expansion. A large number of Lebanese tree species have unexplored economic potential as either ornamental or medicinal plants. This study aimed at exploring the effects of two nitrogen fertility treatments on the growth and water use of 2-year-old Cercis siliquastrum seedlings. C. siliquastrum seeds were collected from different locations and mother trees in Lebanon in mid-Aug. 2001. Two-year old plants were then transplanted into 3-gal. containers and were randomly assigned to one of two N fertility programs, 25 ppm or 100 ppm. Plants from all redbud sources were significantly taller in the low N treatment and had significantly higher RGR than plants growing at 100 ppm N. On the other hand, plants growing at 100 ppm N level had significantly higher LAR and lower NAR than plants growing at 25 ppm N. There were significant differences in LAR and plant heights among the different sources. Water use was conducted monthly. It ranged from 3.6 × 10-4 to 1.3 × 10-3 g·cm Ht-1 per hour at 25 ppm and from 2.6 × 10-4 to 1.3 × 10-3 g·cm Ht-1 per hour at 100 ppm N through the experiment.

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Paul B. Redman and John M. Dole

The postharvest attributes of six specialty cut flower species were studied. First year results indicate that Achillea filipendulina `Coronation Gold' had a vase-life of 10.7 days in deionized water (DI) and can be stored one week at 1.7°C and shipped for one day. Buddeleia davidii (Butterfly Bush) had a vase life of 3.8 days in DI water and tolerated two weeks of cold storage and two days of shipping. Celosia plumosa `Forest Fire' (Plume Celosia) had a vase-life of 5.9 days in DI water and tolerated 2 days of shipping. Cercis canadensis (Redbud) had a vase-life of 9 days in DI water and tolerated one day of shipping. Echinacea purpurea `Bright Star' (Purple Coneflower) had a vase-life of 4.6 days in DI water and tolerated 2 weeks of storage and five days of shipping. Helianthus maximilianii (Maximillian Sunflower) had a vase-life of 6.3 days in DI water and tolerated one week of storage. In addition, silver thiosulfate and 8-hydroxyquinoline citrate increased vase-life of Buddeleia davidii, Celosia plumosa, Echinacea purpurea, and Helianthus maximilianii.