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  • Author or Editor: B. K. Harbaugh x
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Abstract

When cultivars of chrysanthemums, Chrysanthemum morifolium Ramat. were evaluated for resistance to the vegetable leafminer, Liriomyza sativae Blanchard, more differences among mean leafmines occured as each flowered than when biweekly evaluations were made before harvest. Pinched plants at this time also had more leafmines than unpinched plants, probably because of the increased maturation time and, hence, increased exposure to the leafminer population. When cultivars were evaluated simultaneously after they all had flowered, pinched plants had fewer complete leafmines on 2 of 10 cultivars.

Open Access

Abstract

Flowering Kalanchoe blossfeldiana Poelln, exposed to various concentrations of ethylene (0-1 μl/liter of air) at 23.5°C for 2 and 3 days were injured at levels of ethylene greater than 0.5 μl/liter of air for 2 or more days. Ethylene induced leaf abscission and chlorosis, and closed open florets (sleepiness). Sleepy florets failed to re-open. Bud florets were not as severely injured by ethylene as open florets. Bud florets opened when removed from an ethylene environment but their opening was delayed. Florets on plants exposed to 2.5 μ1 ethylene/liter air for 3 days at 6°C were slightly injured. At 2.5 μl ethylene/liter air, severity of injury increased as temperature increased.

Open Access

Abstract

Stored ‘Candidum,’ ‘Carolyn Whorton,’ and ‘Frieda Hemple’ caladium tubers were soaked for 0, 4, 8, 16, 32, or 64 hours in 0, 250, 500, or 1000 mg/liter gibberellic acid (GA3) solutions to determine if flowering could be enhanced during the subsequent forcing period. Mean number of inflorescences produced per plant with no soaking was 0.2, 0.7, and 0.0 for ‘Frieda Hemple,’ ‘Candidum,’ and ‘Carolyn Whorton’ respectively, while tubers soaked in 250 mg/liter GA3 for 16 hours at 23°C averaged 2.4, 3.7, and 4.0 inflorescences per plant, respectively. There was no significant difference in number of inflorescences per plant from tubers treated with 250, 500, and 1000 mg/liter GA3. Optimum soaking time was 8 hours for ‘Frieda Hemple’ and ‘Carolyn Whorton,’ and 16 hours for ‘Candidum.’

Open Access

Abstract

Daily water use for potted Chrysanthemum ×morifolium Ramat. ‘Spirit’ was estimated from pan evaporation and plant height data collected over 2 seasons using 3 different growing environments (glass greenhouse, saranhouse, and outside—no structure). Regression equations derived using pan evaporation and plant height were not significantly improved with the inclusion of plant width as an additional variable to estimate water use.

Open Access

Abstract

A hypothesis was tested that the cause of a damaging marginal bract necrosis common to ‘Gutbier V-14 Glory’ poinsettia is a deficiency of Ca that is expressed when the rapidly growing bract outdistances the current supply of Ca. Plants were grown in the greenhouse in a sedge peat-EauGallie sand mix with fertility adjustments designed to moderately enhance Ca deficiency. Twice-weekly foliar applications of Ca (432 ppm) were begun at the stage of first bract coloration to attempt to prevent necrosis. In addition to bract necrosis, puckering of bracts occurred on controls but not in Ca-treated plants. In another experiment, induced Ca deficiency symptomology included bract necrosis. Calcium chloride spray essentially prevented the necrosis. Necrotic bract marginal tissue had 0.07% Ca, whereas sprayed tissue contained more than three times this Ca concentration.

Open Access