Ixoras (Ixora L.) growing in calcareous sandy soils are highly susceptible to a reddish leaf spot disorder. Symptoms appear on the oldest leaves of a shoot and consist of irregular diffuse brownish-red blotches on slightly chlorotic leaves. Symptoms of K deficiency, P deficiency, and both K and P deficiency were induced in container-grown Ixora `Nora Grant' by withholding the appropriate element from the fertilization regime. Potassium-deficient ixoras showed sharply delimited necrotic spotting on the oldest leaves, were stunted in overall size, and retained fewer leaves per shoot than control plants. Phosphorus-deficient plants showed no spotting, but had uniformly brownish-red older leaves and olive-green younger foliage. Plants deficient in both elements displayed symptoms similar to those observed on landscape plants. Symptomatic experimental and landscape ixoras all had low foliar concentrations of both K and P.
Timothy K. Broschat
Li-Yun Chen, Chien-Young Chu, and Min-Chang Huang
Experiments were conducted on 6-month-old chinese ixora (Ixora chinensis Lam.) from February 1999 to April 2000. Floral development was studied with scanning electron microscopy (SEM) to determine the flowering sequences. Morphological characters were used to clarify the stages of flowering processes. The time of organogenesis and flowering arrangement was established through field observations. Floral evocation occurred in early September, floral initiation occurred in the middle of September and floral differentiation began in late September. A distinctly convex apex with bracts around the shoulder indicated the beginning of reproductive development. Subsequently, primary inflorescence axes were observed and differentiated into secondary, tertiary, and quaternary inflorescence axes consecutively in about one and a half months. Once the terminal apex reached the inflorescence bud stage, it would flower without abortion, and this may be assessed as no return. The sepals, petals, stamens, and pistil were well developed thereafter and anthesis was achieved in January through March in the following year. The observation of floral differentiation sequences and investigation of floret arrangement made it certain that chinese ixora had cymose inflorescence (cyme), but not corymb. A quadratic equation was established to predict floret number from the differentiation level (a quantitative description of differentiation stage) of a developed inflorescence.
Timothy K. Broschat
`Petite Yellow' dwarf ixoras (Ixora spp.) were grown in an alkaline substrate (3 limestone gravel: 2 coir dust) or a poorly aerated composted seaweed substrate to induce iron (Fe) chlorosis. Chlorotic plants were fertilized every 2 months with soil applications of 0.1 g (0.0035 oz) Fe per 2.4-L (0.63-gal) pot using ferrous sulfate, ferric diethylenetriaminepentaacetic acid (FeDTPA), ferric ethylenediaminedi-o-hydroxyphenylacetic acid (FeEDDHA), Hampshire Iron (FeHEDTA plus FeEDTA), ferric citrate, iron glucoheptonate, or DisperSul Iron (sulfur plus ferrous sulfate). Additional chlorotic ixoras growing in a substrate of 3 sedge peat: 2 cypress sawdust: 1 sand were treated every 2 months with foliar sprays of Fe at 0.8 g·L-1 (0.11 oz/gal) from ferrous sulfate, FeDTPA, FeEDDHA, ferric citrate, or iron glucoheptonate. Only chelated Fe sources significantly improved ixora chlorosis when applied to the soil, regardless of whether the chlorosis was induced by an alkaline substrate or a poorly aerated one. As a foliar spray, only FeDTPA was effective in improving chlorosis in dwarf ixora. Leaf Fe content either showed no relationship to plant color or was negatively correlated with plant chlorosis ratings.
Timothy K. Broschat and Kimberly A. Klock-Moore
Areca palms [Dypsis lutescens (H. Wendl.) Beentje & J. Dransf.], spathiphyllums (Spathiphyllum Schott. `Figaro'), ixoras (Ixora L. `Nora Grant'), tomatoes (Lycopersicon esculentum Mill. `Floramerica'), marigolds (Tagetes erecta L. `Inca Gold'), bell peppers (Capsicum annuum L. `Better Bell'), and pentas [Pentas lanceolata (Forssk.) Deflers. `Cranberry'] were grown in a pine bark-based potting substrate and were fertilized weekly with 0, 8, 16, 32, or 64 mg (1.0 oz = 28,350 mg) of P per pot. Shoot, and to a much lesser extent, root dry weight, increased for all species as weekly P fertilization rate was increased from 0 to 8 mg/pot. As P fertilization was increased from 8 to 64 mg/pot, neither roots nor shoots of most species showed any additional growth in response to increased P. Root to shoot ratio decreased sharply as P fertilization rate was increased from 0 to 8 mg/pot, but remained relatively constant in response to further increases in P fertilization rate.
Timothy K. Broschat
new commercial and residential landscapes in Florida. Physical and chemical properties of these soils are provided in Broschat (2015) . The design was split plot (two soil types) with three shrub species (bush allamanda, ixora, and surinam cherry) and
Christopher Ramcharan, Dewayne L. Ingram, Terril A. Nell, and James E. Barrett
Short-term effects of root-zone temperatures (RZT) of 28, 33, 38, and 43C for 6 hours daily on container-grown Musa spp. (AAA) `Grande Naine' and Ixora chinensis L. `Maui' were determined under greenhouse and growth room conditions. Diurnal fluctuation of leaf carbon assimilation (LCA) was altered by treatments. In the growth room at 43C, the maximum LCA occurred about midday for banana, but not until afternoon in ixora. LCA was highest (0.53 mg CO2/m2 per sec) in banana with a 33C RZT under greenhouse conditions, while it was equally high (0.74 mg CO2/m2 per sec) at 33 and 38C in a growth room. In ixora, 33C induced the highest LCA (0.40 mg CO2/m2 per sec) in the greenhouse at 1200 hr, but there were no apparent differences in midday LCA between plants with RZT of 28, 33, and 38C in the growth room. Effects of RZT and environment on the daily fluctuations of gaseous exchange processes raise questions about using measurements at only one time during the day to separate treatment effects.
Edward Bush, Ann L. Gray, Virginia Thaxton, and Allen Owings
Previous research has shown the effectiveness of prodiamine (FactorÆ)as a preemergent herbicide. The objective of this experiment was to evaluate the efficacy and phytotoxicity of prodiamine applied to several woody ornamental and weed species. Phytotoxicity effects were evaluated on eight ornamental species: azalea (Rhododendron indicum `Mrs. G.G. Gerbing'), dwarf yaupon (Ilex vomitoria `Nana'), dwarf mondograss (Ophiopogon japonicus `Nana'), ixora (Ixora coccinea), lantana (Lantana camara `New Gold'), Southern live oak (Quercus virginiana), weeping fig (Ficus benjamina), and daylily (Hemerocallis fulva). Preemergent herbicide treatments (control-nontreated, 2 lbs aia Factor®, and 4 lbs aia Factor®) were applied to ornamentals twice during the experiment at twelve week intervals. There was a reduction in top dry weight for azalea and dwarf mondograss for both 2 and 4 lbs aia treatments. No significant growth reductions were measured for daylily, dwarf yaupon, ixora, lantana, live oak, and weeping fig. The efficacy experiment consisted of four weed species: barnyardgrass (Echinochloa crusgali), crabgrass (Digitaria sanguinalis), coffeeweed (Sesbania exaltata), and pigweed (Amaranthus retroflexus) and five preemergence herbicide treatments (control-nontreated, control-Rout® at 100 lbs/A, Factor® 1 lb aia, Factor® 2 lbs aia, and a tank mixture of Factor® 1 lb aia plus Gallery® 1 lb aia) applied to bark-filled containers. Twenty-five weed seeds of each species were broadcast over each container following herbicide applications. The high rate of Factor®, Rout®, and the combination of Factor®+Gallery® significantly reduced weed dry weight compared to the control. All preemergence herbicides significantly reduced weed counts and height in a similar manner.
Alan W. Meerow
Growth of Pentas lanecolata (Forssk.) Deflers `Starburst Pink' and Ixora coccinea L. `Maui' was compared in container media using sphagnum peat, sedge peat, or coir dust as their peat components. Growth index and top and root dry weights of both crops were significantly better in coir-based medium than sedge peat-based medium. Pentas grew equally well in coir- and sphagnum peat-based medium. Growth index and top dry weight of Ixora were significantly lower in the coir-based than the sphagnum peat-based medium, although root dry weights were equal. This difference was not apparent and may have been caused by N drawdown in the coir-based mix. The sedge peat-based medium had the highest air porosity and the lowest water-holding capacity of the three media at the initiation of the trials, but at the termination of the study, it showed a reversal of these characteristics. The coir-based medium showed the least change in these attributes over time. Coir dust seems to be an acceptable substitute for sphagnum or sedge peat in soilless container media, although nutritional regimes may need to be adjusted on a crop-by-crop basis.
Alan W. Meerow
Coir is the name given to the fibrous material that constitutes the thick mesocarp of the coconut fruit (Cocos nucifera L.). The long fibers of coir are extracted from the coconut husk and utilized in the manufacture of various products. The short fibers and dust (“pith”) left behind have accumulated as a waste product. Coir pith is light to dark brown in color and consists primarily of particles in the size range 0.2-2.0 mm (75-90%). In composition, it is 65-70% lignin and 20-30% cellulose. To date, few replicated tests have assessed the performance of coir pith as a plant growth medium. From April, 1993 to April, 1994, four ornamental crops (pentas, ixora, anthurium and majesty palm) were grown in container media that differed only in the peat fraction (40%), either sphagnum, Florida (sedge) peat, or coir pith. On the basis of plant growth parameters, coir pith was superior to sedge peat as a medium component (though only marginally for the anthurium) and at least equal to sphagnum peat. In addition to physical qualities equal to or better than sphagnum peat, coir decomposes more slowly than either sedge or sphagnum peat, withstands compression better and is easier to wet than peat. There are also no ecological drawbacks to the use of coir -- a waste product -- relative to the harvest of peat from wetland ecosystems.
Dewayne L. Ingram, John M. Ruter, and Chris A. Martin
exposure duration for Ixora coccinea L. (ixora) root cell membranes were 38 and 221 min for treatment temperatures of 55 and 50 °C, respectively. Ixora roots exposed to 48 °C were not injured by a 300-min exposure ( Ingram and Ramcharan, 1986 ). Research