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  • Author or Editor: Gary J. Kling x
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Cornus sericea L. rooted cuttings were held in cold storage for 60 days and then transferred to a growth chamber in hydroponic culture. Roots and shoot tips were sampled during storage and through resumption of vegetative growth. Samples were analyzed for abscisic acid (ABA), indole-3-acetic acid (IAA), zeatin, zeatin riboside, glucose, fructose, sucrose, and starch. Budbreak was associated with increasing levels of the cytokinins and IAA, and decreasing levels of sucrose and starch in the shoot tips. Regeneration of new roots was preceded by an increase in the cytokinins and IAA, and a decrease in ABA in roots. Root sucrose increased nearly two times 1 week after budbreak and starch content generally decreased throughout the experiment. The results agree, in general, with previous reports indicating decreasing levels of ABA and increasing levels of cytokinins to be associated with root regeneration and budbreak. They also indicate that, of the four carbohydrates studied, sucrose levels changed most dramatically during the root regeneration and budbreak processes.

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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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Abstract

The genus Quercus comprises a major group of woody landscape plants that differ widely in root system morphology and recovery from transplanting (2, 6). Quercus alba has a coarse root system and is more difficult to transplant than the more fibrous-rooted Quercus rubra (2).

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Abstract

Root systems of two Magnolia taxa were treated with spray applications of auxins to determine their effects on root regeneration. Spray application of 500 ppm of IBA doubled the number of adventitious roots regenerated from the cut ends of main roots in 1-year-old cuttings of Magnolia × Soulangiana (Soul.-Bod). Higher concentrations of IBA inhibited root regeneration. Auxin applications did not increase the number of lateral or branch roots. Root systems of Magnolia × Soulangiana were treated with spray applications of ethanol to determine effect of IBA on root regeneration. A significant negative linear relationship was found between ethanol concentration and the number of adventitious roots initiated at the cut ends of main roots. Ethanol concentrations of 12.5% to 70% had no effect on the number of lateral roots. Root regeneration of Magnolia × ‘Betty’ was not stimulated with soil drench applications of 250 to 1000 ppm IBA. IBA and NAA concentrations of 1000 to 4000 ppm were inhibitory. Chemical names used: 1H-indole-3-butyric acid (IBA), 1-napthaleneacetic acid (NAA).

Open Access

Growers, nurseries, landscape contractors and installers, and those responsible for maintenance have observed a trend that trees are too deep within the root ball. This study addresses the relationship between planting depth and its effect on tree survival, root growth, root architecture, and caliper growth. The experiment was initiated to determine the effect of planting depth on nursery-grown trees. Three-year-old, 2.1–2.7 m, bare-root liners of Acer platanoides `Emerald Lustre', Fraxinus americana `Autumn Purple', Fraxinus pennsylvanica `Patmore', and Gleditsia triacanthos f. inermis `Shade Master' were planted in April 2004 in a completely randomized design with 20 replications per treatment per species. The trees were selected so that the distance between the graft union and the trunk flare was consistent. Trees were planted with the graft union 15.2 cm below the soil surface, or with the base of the graft union at the finished grade or with the trunk flare at the finished grade. The trees were grown in a nursery field setting with minimal supplemental watering. There were no differences in stem caliper growth at the end of two seasons in any of the four species. Root dry mass, stem elongation, and rooting structure were determined on a representative sample of trees while others were planted into the landscape for a long-term study of the effects of the original planting depth on landscape performance.

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Abstract

Methanolic extracts from leaves, young stems, and old stems of five Acer (maple) spp. were tested for their effects on adventitious root initiation in mung bean (Vigna radiata Wilcox’) cuttings. An extract from the leaves of A. ginnala strongly stimulated root initiation, and the active compounds in this fraction were not synergistic with IAA. This extract was more stimulatory than IAA on mung bean cuttings and stimulated root initiation in softwood cuttings of A. saccharinum and A. griseum. Preliminary characterization of this extract indicates that it is a phenolic compound and/or a weak acid. Chemical name used: 1H-indoIe-3-acetic acid (IAA).

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UIPLANTS is a computer-based reference to help identify, culture, and use woody landscape plants for the northern and central United States. The program provides a comprehensive reference to serve the educational and professional communities with more than 8000 high-quality color images and textual descriptions of more than 900 species and cultivars. Special features include a highly flexible slide show and the ability to compare any two images side by side. Student activity can be tracked, creating detailed logs of student use patterns and times.

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An integrated approach to weed control in nursery containers is crucial if herbicide applications during the growing season are to be reduced. This experiment, conducted in 2002 and 2003 in Urbana, Ill., evaluated rice hulls, leaf-waste pellets, and pine bark as herbicide carriers for the preemergence herbicides oryzalin at 2 lb/acre a.i. and diuron at 1 lb/acre a.i. The efficacy of the treatments in controlling annual weeds and the phytotoxic effects of the treatments on the woody plant species were evaluated in separate completely randomized designs. For the efficacy experiment, no ornamental plants were present and containers were each seeded with a mixture of 1:1:1 (by volume) of annual bluegrass (Poa annua), common groundsel (Senecio vulgaris), and shepherd's purse (Capsella bursa-pastoris) immediately after treatment applications. For the phytotoxicity experiment, ‘Goldflame’ spirea (Spiraea japonica), ‘Hetz Midget’ american arborvitae (Thuja occidentalis), and ‘Snowmound’ nippon spirea (Spiraea nipponica) were evaluated. No weed seeds were sown in the phytotoxicity containers. Treatments for both experiments included spray applications of herbicides with water or with one of the organic mulches as a carrier or one of the mulches alone. Evaluations were done 45 and 120 days after treatment (DAT) in both years. The organic carriers with herbicide sprays gave efficacy visual ratings equivalent to water as a carrier for both herbicides. Phytotoxicity was not observed in the spirea species in either year. For ‘Hetz Midget’ american arborvitae in 2002, diuron with water had the highest visual phytotoxicity rating. Diuron phytotoxicity on the ‘Hetz Midget’ american arborvitae was alleviated when diuron was applied with any of the three mulches as a carrier. Pine bark treatments increased plant biomass for ‘Goldflame’ spirea in 2003, 45 DAT. At 120 DAT in 2002, pine bark gave increased plant biomass as compared with no organic mulch treatments for ‘Goldflame’ spirea. The study was conducted to ascertain whether the use of organic mulches as carriers could reduce phytotoxic effects of a herbicide on container-grown woody ornamentals, improve crop plant biomass, and act as a herbicide carrier for container-grown woody ornamentals.

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