Populations of twospotted spider mite (Tetranychus urticae Koch) infesting greenhouse Dieffenbachia maculata (Lodd.) G. Don cv. Perfection, were significantly reduced 2 weeks after release of predators, Phytoseiulus macropilis (Banks). Numbers of T. urticae at predator introduction and numbers of predators introduced had a direct effect on time required to bring about reductions in spider mite populations and maintenance of high quality plants. Numbers of T. urticae infesting interior D. maculata were suppressed at predator to prey ratios of 1:5, 1:10 and 1:20, but based on foliar damage, 1:20 ratio was not effective from an aesthetic standpoint. Suppression of T. urticae populations was more rapid at higher P. macropilis to T. urticae ratios.
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.
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.
Maranta leuconeura Kerchoviana E. Morr. grew better at 15 than 21°C minimum night temperature (MNT), while Aglaonema commutation Schott. ‘Fransher’ and Aphelandra squar-rosa Nees. ‘Dania’ were unaffected by reduced MNT. Dieffenbachia maculata (Lodd.) G. Don ‘Marianne’ and Nephrolepis exaltata (L.) Schott. ‘Bostoniensis’ (Boston Fern) grew slightly better at 21 and 18° MNT while growth of Epipremnum aureum (Linden & Andre) Bunt (Golden Pothos) improved with each increase in MNT. Irrigation with 5,10,15 or 20° water had no effect on plant growth or grade.
Data indicated the N-P2O5-K2O ratio of 1-1-1 is unnecessarily high in P2O5 and K2O for Dieffenbachia maculata (Lodd.) G. Don ‘Exotica’, Dracaena sanderana Hort. Sander ex M. T. Mast, Maranta leuconeura var. kerchoviana E. Morr., and Peperomia obtusifolia (L.) A. Dietr. Plant growth and tissue nutrient levels were more sensitive to changes in N fertilization level than P and K. Tissue N was a more sensitive indicator of optimum growth and fertility practices than P or K.
Leaching of N into ground water has become a major pollutant in several areas of the U.S. The potential for regulation of environmental plant producers is increasing, but limited information is available on cultural management. This factorial experiment tested a liquid and a slow release fertilizer source at 3 irrigation levels (100, 200 or 300 ml/20 cm pot/2 times/wk) for NH4+, NO3- and P found in leachate collected weekly for 12 weeks. Plant quality and fresh weight for all treatments was similar, but large variations occurred in NH4+, NO3- and P levels in leachate due to irrigation level. Increasing irrigation level from 100 to 300 ml twice weekly resulted mainly in linear increases of NO3- present in leachate, with levels as high as 159 mg/l observed near the end of the production cycle. NH4+ levels were most affected by irrigation and highest early in the experiment, but were generally lower than 1 mg/l. P levels ranged from 1.4 to 16.0 mg/l in leachate with responses to fertilizer source and irrigation mainly during the first 6 weeks.
Brassaia actinophylla Endl. and Dieffenbachia maculata (Lodd.) G. Don ‘Perfection’ were grown under 0.5, 1.0 or 2.0 klx Cool White fluorescent light for 1 year in in anterior environment. Growth increased as light level increasede Increasing rate of fertilizer application from liquid or slow release fertilizer had no effect on growth at 0.5 klx, but a large effect at 2.0 klx. Influence of light and fertilizer levels on elemental tissue content is discussed.
Physical characteristics were determined for 5 potting media composed of varying ratios of Florida sedge peat and pine bark subjected to compaction pressures of 0.0, 0.1, 0.2, or 0.3 kg/cm2. Percent noncapillary pore space decreased as compaction pressure and amount of peat in the mixture increased, while water holding capacity by volume increased with peat addition and compaction pressure. Top growth of Pilea pubescens ‘Silver Tree’ in compacted media was generally as good as in noncompacted media, but root growth was restricted.
Six potting media (Metro Mix 200, 300, 350, 500, 2 sedge peatmoss : 1 pine bark : 1 cypress shavings (by volume) and 3 sedge peatmoss : 1 mason sand (v/v) were compacted at 0, 0.1, 0.2, or 0.3 kg·cm−2. Noncapillary pore space was reduced in all media at 0.1 kg·cm−2 as compared to 0 pressure, but increasing compaction pressure had more effect on 2:1:1 than on 3:1 or Metro Mixes. Pilea pubescens Liebm. ‘Silver Tree’ and Dracaena sanderana Hort. Sander ex M. T. Mast. were used in two additional experiments where the six media were combined factorially with compaction pressures of 0.1 and 0.2 kg·cm−2 and irrigation rates of two or four applications/week. Both genera were affected more by potting media and irrigation levels than by compaction, with best plants generally produced in Metro Mixes receiving the higher irrigation level.
Grade and vine length of P. oxycardium growing on totem poles increased as shade level decreased from 80 to 40%. Highest grade was obtained with Osmocote, followed by liquid fertilizer and MagAmp. Generally, 785 kg N/ha/3 months was adequate for good growth, although interactions occurred with light intensity as shown by lack of fertilizer response at high shade levels. Foliar N levels were higher in 80% shade but quality decreased. MagAmp increased P and Mg and decreased Ca and K levels in foliage, while Osmocote increased N.