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  • Author or Editor: A. R. Chase x
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Ficus lyrata Warb. ‘Compacta’ plants were grown with various rates of Osmocote 19N-2.6P-10K for 2 months prior to inoculation with Pseudomonas cichorii (Swing.) Stapp. Optimal plant growth occurred at rates from 4 to 13 g/12.5-cm pot in the spring, and 4 to 16 g/12.5-cm pot in the summer and fall. Percentage of leaf area affected with Pseudomonas cichorii was correlated to fertilizer level at rates between 4 and 16 g/12.5-cm pot. Disease rating was lowest for underfertilized plants (1 g/12.5-cm pot) increased at the 4-g rate and decreased at higher rates according to the following equation (y = 14.39 - 0.72x, R2 = 0.86).

Open Access
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Abstract

Storage at 4.5°C prevented decay of cut fronds of leatherleaf fern [Rumohra adiantiformis (G. Forst) Ching] artificially inoculated with Cylindrocladium heptaseptatum Sobers, Alfieri, & Knauss and/or naturally infected with C. pteridis Wolf and increased frond vase-life compared to 24° storage. Storage at 4.5° for 10, 21, and 31 days did not affect subsequent frond vase-life. Inoculation of fronds decreased vase life by 11% in one experiment and had no effect in a second. Prestorage dips in benomyl suspensions at concentrations as low as 38 ppm reduced frond decay by 82% when stored at 24° and increased vase-life of fern stored at both 4.5° and 24°. Benomyl [methyl l-(butylcarbamoyl)-2-benzimidazole-carbamate] dips at concentrations as high as 300 ppm had no detrimental effect on vase-life. Iprodione [3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide] had no effect on vase-life.

Open Access
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Abstract

Information regarding fertilization of Begonia × semperflorens-cultorum, Hort. (fibrous-rooted begonia) is sparse and does not provide sufficient parameters for plant production (1-3). The purpose of the following experiment was to evaluate effects of various rates of a slow-release fertilizer on plant growth.

Open Access
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Abstract

The effect of fertilizer level (1.2-41.3 g Osmocote 19N-2.6P-10K per 15-cm pot) was tested in factorial experiments with air temperature [13.5° to 21°C (winter) or 32° to 41° (summer)] and light level (47-80% shade) on Syngonium podophyllum Schott ‘White Butterfly’. Optimal shoot growth was obtained for plants fertilized with 4.9 to 19.5 g Osmocote per 15-cm pot for 3 months under greenhouse conditions during the summer and winter (recommended rate is about 5.0 g). Slight reductions in plant growth occurred at higher rates. Interactions between fertilizer level and air temperature were rarely significant. Optimal shoot growth was obtained for plants with a maximum air temperature between 32° and 41° during the summer and a minimum air temperature of 18.5° and 21° during the winter. High-quality plants were produced with fertilizer rates from 4.9 to 34.0 g per 15-cm pot for 3 months under shadehouse conditions. Plants grown with 200 μmol·s-1·m-2 (80% shade) had fewer leaves, were taller, whiter (color), had lower-quality grades, lower fresh weight of shoots, higher percentage of pots with healthy-appearing roots, and produced larger leaves than those grown with 700 μmol·s-1·m-2 light (47% shade). Interactions between fertilizer and light levels were not significant.

Open Access
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Hibiscus rosa-sinensis L. plants treated three times with 850 mg·liter-1 of the growth retardant chlormequat chloride (CCC) were less susceptible to infestation with Tetranychus urticae (Koch) than water-treated control plants. The difference in mite numbers was noted within 8 days after releasing mites onto test plants. Mean number of mites per treated plant was 3.7, compared to 30 on nontreated plants. This activity was observed on all treated plants 6 months after applying CCC. Significant differences were observed on treated plants that were defoliated and allowed to produce new foliage before being evaluated. Therefore, surface chemical residues were not responsible for reducing mite infestations on CCC-treated plants.

Free access
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Abstract

Excessive fertilization produces high soluble salts, resulting in root damage and poor quality foliage. Although usually determined by mixing soil with water, conductivity also can be determined by mixing with leachate obtained by pouring water through the potting medium.

Open Access
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Abstract

Of 4 Spathiphyllum species and 5 cultivars tested for sensitivity to Cylindrocladium spathiphylli root and petiole rot, 3 demonstrated resistance. Spathiphyllum floribundum, S. floribundum ‘Mini’, and S. cannifolium were resistant, whereas all others tested were susceptible. Twenty hybrids from a cross of S. lechlerianum × S. floribundum also were tested and found resistant to C. spathiphylli, indicating potential for development of new Spathiphyllum cultivars resistant to this serious pathogen.

Open Access
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Abstract

Trials in the greenhouse and growth chambers were performed to evaluate the influence of fertilizer level and temperature on sensitivity of Spathiphyllum cv. Clevelandii to acephate insecticide. Plant quality was not influenced consistently by fertilizer level in all tests, although highest-quality plants usually were produced with recommended fertilizer levels (3 g/15-cm pot Osmocote 19N-6P-12K). Plants were grown at fertilizer levels up to 15 g/15-cm pot with those grown between 22° and 27°C undamaged, while those grown at 32° had severe foliar necrosis and were stunted. Increases in either fertilizer level or temperature resulted in increased levels of phytotoxicity when plants were sprayed with recommended rates (0.4 g/liter) of acephate insecticide. An interaction occurred between temperature and fertilizer level in growth chamber trials.

Open Access
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Abstract

Peperomia obtusifolia (L.) A. Dietr. were grown with various fertilizer levels (0.5–3.5 g Osmocote 19-3-10/10-cm pot) and irrigation frequencies (1, 2, or 3 times/week). Plants were inoculated with Pythium splendens Braun 2–6 months after initiation of fertilizer treatments. Top and root quality responses were linear and quadratic with respect to fertilizer level. One month after inoculation, root quality decreased the most for plants with the highest irrigation frequency and the lowest fertilizer level. Plants fertilized at the highest rate did not show a significant decrease in root quality. There was an interaction between fertilizer and irrigation rates as measured by plant height, quality, and disease ratings. Poorest quality plants resulted when watered 3 times/week and fertilized with 0.5 g Osmocote/pot. Highest quality plants resulted when watered 2 or 3 times/week and fertilized with 2.5 g Osmocote/pot.

Open Access
Authors: and

Abstract

Factorial experiments, including three potting media, two potting medium temperatures, and two air temperatures were used to evaluate growth of Nephrolepis exaltata ‘Fluffy Ruffle’ (Boston fern) infected with Rhizoctonia solani (the causal agent of aerial blight). Potting medium mixtures of sphagnum peat-sand, sphagnum peat-pine bark, and sphagnum peat-vermiculite-perlite did not affect severity (percentage of foliar infection) in four of five tests. Plant quality was highest for plants grown in peat-vermiculite-perlite in two of four tests. Potting medium temperature of 32°C reduced percentage of foliar infection in four of five tests, and plant quality in three of four tests. Fresh weights of shoots or roots were not affected consistently by potting medium temperature at 32°. Air temperatures ranging from 35° to 38° were favorable for disease development, with reduced development at temperatures above 35°. In vitro radial growth of R. solani isolates was optimal at ≈30° with a statistically significant reduction at 35°.

Open Access