Foliar sprays of 5,000 ppm dikegulac [sodium salt of 2,3:4,6 bis-0-(1-methylethlidene)-a-L-Xylo-2-hexulofuranosonic acid (Atrinal)] applied to 4 cultivars of greenhouse forcing azaleas (Rhododendron spp.) 1 week after shearing, produced plants with more shoots than untreated plants and plants treated with 42,000 ppm Off-Shoot-O (methyl esters of fatty acids: 4% C6, 56% C8, 38% C10 and 2% C12). Increases in shoot number on dikegulac-treated plants generally did not increase the number of flowers. Plants treated with sprays of 3,000 to 6,000 ppm dikegulac initially exhibited temporary shoot growth inhibition but had fewer by-pass shoots at flowering.
Dry weight and total plant height of Hex cornuta IindL cv. Burfordii and Thuja occidentalis L. were greater in municipal compost-amended medium than in sphagnum peat moss-amended medium. Viburnum burkwoodii Burkwood did not show any differences in the two media. Generally, constant and biweekly liquid fertilizer regimes produced more growth than other regimes.
The growth retardants ancymidol, flurprimidol, and chlormequat chloride were incorporated into plaster of paris tablets and compared to drenches on various plants. Ancymidol tablets were as effective as drenches in controlling height and increasing racemes of Clerodendrum thomasoniae Balf. (southern bleeding heart). Drenches of ancymidol and flurprimidol reduced the height of Lilium longiflorum Thunb. (Easter lily) more than tablets; flurprimidol reduced Lilium height more than ancymidol. Tablets reduced the height of Euphorbia pulcherrima Willd. ex Klotzsch (poinsettia) cvs. Topstar and V-14 Glory, but not C-1 Red. Ancymidol drenches produced shorter ‘C-1 Red’ and ‘V-14 Glory’ plants than tablets. Tablets reduced bract diameter more than drenches. Flurprimidol tablets produced the smallest bracts. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); α-(1-methylethyl)-α-[4-(trifluoromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol); 2-chloro-N,N,N-trimethylethanaminium chloride (chlormequat chloride); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide).
Passiflora caerulea L., blue passion-flower, has been hybridized with other species to produce hybrids of ornamental value and has been grown as a potted plant. P. edulis Sims, the passion fruit, has handsome 3-lobed leaves and large white ornamental flowers. Both species are large vines that would make interesting potted, patio hanging-basket or trellis plants if their stem elongation could be controlled.
Paclobutrazol drenches were more effective in retarding chrysanthemum (Chrysanthemum × morifolium ‘Charm’) plant height than paclobutrazol incorporated in plaster-of-paris tablets, injected hydrogels, and gelatin capsules applied at the same rate (0.5 mg a.i./15-cm pot) in three experiments. Capsules containing paclobutrazol also controlled plant height effectively in all three experiments. Drenches consistently reduced plant area, whereas a 50-ppm paclobutrazol spray did not. Paclobutrazol tablets, gels, and capsules reduced plant area in two of three experiments. Drenches were the only treatment to reduce flower number per plant. Chemical name used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Total immersion of Pseuderanthemum atropurpureum L. H. Bailey, Sanchezia speciosa J. Leonard, and Strobilanthes dyeranus M. T. Mast. cuttings in aqueous solutions of the morphactins chlorflurecol and chlorflurenethol prior to propagation retarded plant growth 16 weeks after rooting. Height of Sanchezia and Strobilanthes also was reduced by dips of chlorfluren and dichlorflurecol and chlormequat chloride. Morphactins caused abnormal growth on Pseuderanthemum and Strobilanthes. Dips of PBA reduced the height of Pseuderanthemum and Strobilanthes. Pseuderanthemum height also was reduced by ancymidol and ethephon dips, and height was reduced on Strobilanthes by oxathiin and piproctanyl bromide. Chlorflurecol dips reduced plant dry weight of all species. Plant dry weight of Strobilanthes also was reduced by chlorofluren, chloroflurenthol, oxathiin, and PBA immersion. Ethephon, PBA, and chlorflurenthol dips also reduced Pseuderanthemum dry weight. Chemical names used: 2-chloro-9-hydroxy-9H-fluorene-9-carboxylic acid (chlorflurecol); 2-chlorofluorenecarbonic acid-(9)-methylester (dichloroflurecol); 2-chloro-9-hydroxyfluorene-carbonic acid-(9)-p-chlorophenoxyethylester (chloroflurenethol); 2-chloro-N,N,N-trimethylethanaminium chloride (chlormequat chloride); N-(phenylmethyl)-9-(tetrahydro-2H-pyran-2-yl)-9H purin-6-amine (PBA); α-cyclopropyl-α-(4-methoxyphenyI)-5-pyrimidinemethanol (ancymidol); (2-chlorethyl)phosphonic acid (ethephon); 2,3-dihydro-5,6-diphenyl-1,4-oxathiin (oxathiin); 1-(3,7-dimethyloctyl)-1-(2-propenyl)piperidinium bromide, (piproctanyl bromide).
Drenches and sprays of α-cyclopropyl-α (p-methoxyphenyl)-5 pyrimidinemethanol (ancymidol) were comparable to 2,4-dichlorobenzyl-tributylphosphonium chloride (CBBP, Phosfon) in inhibiting stem growth of the ‘Georgia’ Easter lily. Both materials produced plants with enlarged, thin-walled sclerenchymatous stem cells. Some of the higher rates of ancymidol delayed flowering and reduced the number of flowers per plant. Drenches of (2-chloroethyl)phosphonic acid (ethephon) and sprays of ethyl hydrogen 1-propylphosphonate (EHPP) showed some promise as deflowering agents in commercial lily bulb production.
Chamaecereus silvestri (Spreg.) Britt & Rose ‘Peanut cactus’, Mammillaria elongata D.C. ‘Gold Star’, and Opuntia microdasys (Lehm.) Pfeiff. ‘Bunny Ears’ were grown on an 8-hr natural photoperiod (short) or an 8-hr natural plus 4-hr incandescent light from 10:00 pm to 2:00 am photoperiod (long) and treated with single sprays of growth regulators. Ethephon or the long photoperiod increased shoots on Opuntia. Gibberellic acid alone or BA alone increased Mammillaria and Chamaecereus shoot number linearly, whereas GA plus BA reduced shoot number. Chamaecereus and Opuntia plants grown on a long photoperiod produced more shoots than plants grown on the short photoperiod. Ethephon reduced the dry weight of all cacti tested. Dry weight of untreated Mammillaria and Opuntia plants exceeded that of growth regulator-treated plants. Opuntia plants produced more dry weight on the long photoperiod than on the short photoperiod. GA increased the growth of glochids on Opuntia and Mammillaria. Chemical names used: A-(phenylmethyl-1H-purin-6-amine (BA); (2-chloroethyl)phosphonic acid (ethephon); and gibberellic acid (GA).
Of various controlled-release fertilizer materials, tested on African violet (Saintpaulia ionantha H. Wendl) at 300, 600, and 900 kg/ha for leachate soluble salts, Ca, P, K, and Mg and plant injury, Scott 25.0–4.4–8.3 gave the best result and Scott 15.0–8.7–4.2 gave the poorest result. Precise 8.0–4.8–4.2 leachate generally contained more Ca and Mg and lower leachate soluble salts, but was lower in P and K than the other fertilizers. With the exception of Precise, the leachate soluble salts of most of the fertilizers was initially (10th irrigation) too high. The 900 kg/ha rates for some fertilizers caused high leachate soluble salts and plant injury.