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Abstract
Four methods of overwintering container-grown ornamental nursery stock were evaluated. Canopy temperatures of plants unprotected or covered with a thin layer of ice closely followed air temperatures during subfreezing conditions; minimum ambient air temperature was – 16C. Canopy temperatures under white copolymer film fluctuated widely, while canopy and growth medium temperatures of plants continuously irrigated during subfreezing temperatures did not drop below 0C. Root injury of all species and foliar injury of azalea (Rhododendron × ‘Due de Rohan’), euonymus (Euonymus japonica Thunb. ‘Microphylla’ H. Jaeg.), and pittosporum [Pittosporum tobira (Thunb.) Ait.] were least when plants were continuously irrigated or covered with white copolymer film. Foliage of Japanese holly (Ilex crenata Thunb. ‘Compacta’) and dwarf Burford holly (Ilex cornuta Lindl & Paxt. ‘Burfordii Nana’) was not injured with any treatment. Bark splitting of azaleas was most severe under the thinly iced and white copolymer-covered treatments, less severe in the unprotected treatment, and least with continuous irrigation.
Abstract
Dwarf Japanese euonymus (Euonymus japonica Thunb. ‘Microphylla’) and ‘Pink Supreme’ azalea (Rhododendron Xsp.) grown in containers of three diameters (10.2, 15.2, and 20.3 cm), were given three rates of Osmocote 17N-3P-10K (3.6, 7.1, and 10.7 kg·m-3). Response to container volume and fertility was species-dependent. Top growth of euonymus increased in response to both increased medium volume and fertility and was closely related to foliar levels of N, P, and K. Top growth of azalea increased in response to increasing fertility rates in the smallest pots, and to increasing medium volume at the lowest fertilizer rates. With an increase in both fertilizer rate and medium volume, growth of azalea was reduced. Top growth was inversely related to foliar K, but was unrelated to foliar N and P.
Abstract
Dwarf Japanese euonymus (Euonymus japonica Thunb. ‘Microphylla’) and Japanese holly (Ilex crenata Thunb. ‘Compacta’), grown in fresh or aged (1 year) pine bark amended with a slow-release complete fertilizer, were supplied with NH4NO3 weekly at 0, 100, 200, or 300 ppm N. Plant growth, foliar color, leaf tissue N, and leachate soluble salts increased with increasing levels of supplemental N while tissue K, Ca, and Mg decreased. Plant growth, foliar color, and leaf tissue N, P, Ca, and Mg in fresh pine bark equaled or exceeded that in aged pine bark at all levels of supplemental N. Leachate soluble salts, pH, and leaf tissue K was higher in aged pine bark.
Abstract
Three pot/mulch combinations and 2 pot spacings were evaluated as to their effects on growing-media temperatures and growth of ‘Hershey’s Red’ azalea (Rhododendron Xsp.). The highest, maximum temperature and least root and shoot growth occurred in black pots on white clam shell mulch compared to white pots on black polyethylene and to white plywood-shielded pots. Close spacings of pots increased root growth with black pots on white mulch but not with white pots on black mulch. Plants in black pots on white mulch developed the greatest winter foliage discoloration and leaf abscission.
Abstract
Overhead irrigation during the day reduced maximum temperatures and their duration within the plant canopy and the container growth medium, and resulted in increased top and root growth of ‘Hershey’s Red’ azalea (Rhododendron × ‘Hershey’s Red’). Intermittent irrigation for 2.5 min/hr during the day reduced canopy temperature but did not affect growth medium temperature or plant growth.
Abstract
The effects of greenhouse environment and outside weather factors on epidemiology and spore release of powdery mildew of roses (Rosa hybrida L.) caused by the fungus Sphaerotheca pennosa (Wallr.) Lev. var. rosae Wor. were studied. Mildew epidemics were correlated to outside dew point temperatures, and mildew incidence could be reduced to low levels by sulfur vaporization and adopting cultural procedures designed to dry out the greenhouse environment prior to nightfall during seasonal periods when mildew was likely to be prevalent Highest spore release occurred in the period between 1200 to 1600, and was correlated with external variables.
Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the U.S. However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H2O or hydrogen peroxide (H2O2). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of the H2O or H2O2; both nicking and H2O2 increased germination, but not equal to rate of the control in 5 mL H2O or H2O2. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (CV = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seedcoat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.
Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the United States However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H2O or hydrogen peroxide (H2O2). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of H2O or H2O2; both nicking and H2O2 increased germination but not equal to rate of the control in 5 mL H2O or H2O2. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (cv = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seed coat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.
Abstract
Dwarf Burford holly (Ilex cornuta Lindl. & Paxt. ‘Burfordii Nana’), dwarf Japanese euonymus (Euonymus japonica Thunb. ‘Microphylla’), and ‘Hershey’s Red’ azalea (Rhododendron x sp.) were grown in containers in all combinations of 3 diameters (10.2, 15.2, and 20.3 cm) and 3 depths (7.6, 15.2, and 30.5 cm). Top growth of Burford holly, a species with coarse, lateral, and deep roots, increased as pot depth and width increased; root growth was increased in deep pots. Euonymus, a species with a densely branched, medium fine root system, increased in top growth as pot depth and width increased, although the response to pot depth was less than to width. Top growth of azalea, a fibrous and shallow-rooted species, increased as pot width increased but was not affected by pot depth. Root density of euonymus and azalea decreased as pot depth and width increased, whereas relative root depth of azalea was reduced in deep pots.
Designing a landscape involves the selection of plants with certain characteristics such as height, color, hardiness zone, bloom time, etc. A Hypercard stack, which is a specific type of software application for Macintosh computers, was developed to aid landscapers in the location of plants with the desired characteristics. This Hypercard stack, called the “Plant Stack”, is based on the book, Identification Selection and Use of Southern Plants for Landscape Design, by Dr. Neil Odenwald and James Turner. The stack is also useful as an educational tool; for example, it can be used as a set of flash cards. Use of the software for selecting southern plants will be discussed as will use of the same software as an educational tool.