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- Author or Editor: M. Sachs x
- HortScience x
Abstract
Although at each shoot apical meristem, vegetative and reproductive development represent alternative courses of differentiation, we wish to emphasize the quantitative interaction between these two processes particularly with regard to the potential for chemical control. Without exception the known flower promoting or inhibiting substances also have substantial influence on vegetative development (32).
Abstract
Although for an entire plant, vegetative and reproductive development may proceed concurrently, at each shoot apical meristem a transition occurs from leaf production to bract or sepal production at the time of flower initiation. Subsequent stages of reproductive development are equally differentiated from that of vegetative development. Hence, vegetative and reproductive development represent alternative courses of differentiation of apical meristematic tissues.
Abstract
Retardation of runner formation in the fall was obtained in summer-planted strawberry (cv. Tioga) as a result of (2-chloroethyl)trimethylammonium chloride (chiormequat) and succinic acid-2,2-dimethylhydrazide (SADH) spray treatments. No residual effects of the growth retardants on runner development were found in the following spring. The treatments brought about a significant increase in the no. of crowns per plant, but this had no effect on the total yield of the plants. Fruit quality was lowered by the treatments, especially by SADH.
Abstract
Foliar applications of 2, 3, 4, 6-di-o-isopropyl-idene-2-keto-L-gulonate (dikegulac) at rates of 0.2-0.3% resulted in growth reductions comparable with l,2-dihydro-3,6-pyridazinedione (MH) or methyl-2-chloro-9-hydroxyfluorene-9-carboxylate (chlorflurenol). Where terminal leaf abscission occurs, tree appearance after treatment is sometimes better than that of trees treated with either MH or chlorflurenol. Growth reduction from trunk banding with dikegulac n-pentyl ester was observed only on Ulmus parvifolia Jacq.; chlorflurenol in trunk banding has a much wider species range and is effective at lower concn.
Abstract
Foliar application of 0.1 to 1% dikegulac-sodium [sodium 2,3:4,6-di-0-isopropyl-idene-2-keto-L-gulonate (Atrinal)] inhibited (shoot) elongation and axillary bud break for more than 3 months in field grown Xylosma congestum, (Lour.) Merr., Pyracantha coccinea (Roem.), Callistemon citrinus (Curt.), Cotoneaster pannosa (Franch.), and Nerium oleander L. Phytotoxic symptoms were minor in most species, but Nerium, chlorosis of young leaves and necrotic areas on tips of half expanded leaves were noted. Applications made immediately after pruning eliminated this problem. Fully expanded leaves were undamaged and their viability more than 5 months after treatment with 1% solutions were equal to that of control plants. Greenhouse trials with Eucalyptus globulus Labill., Fraxinus uhdei (Wenz.) lingelsh, and Ulmus parvifolia Jacq. indicated that this compound will also be a useful inhibitor for landscape tree species, although at 0.4%, phytotoxicity in Eucalyptus may be too severe for general application.
Abstract
Chemical control of plant height has been achieved for many herbaceous and woody species. Horticultural practices in the greenhouse, orchard, and landscape have been altered to include the use of numerous compounds, the main function of which is to eliminate overgrowth. The problems encountered in selecting and using even the registered materials cannot be readily generalized since each compound presents special difficulties. Nevertheless, for the purpose of this review, 7 challenges to effective use usually presented by all compounds will be discussed, namely: 1) identifying the primary cause of inhibition of stem elongation; 2) timing the application of compounds to the appropriate stage of plant development; 3) determining the best method of application; 4) determining the optimum dosage, formulation, and frequency of application; 5) testing for cumulative phytotoxicity; 6) noting species specificity; and 7) taking note of potential environmental effects. Many chemicals have been made available for testing, but relatively few of them are registered expressly for control of overgrowth (Fig. 1).
Abstract
Morphactins, mixed with non-phytotoxic paraffinic, low molecular weight oil, were applied as bark bands and tested for growth inhibition of trees growing under field conditions. Three species were tested: Monterey pine (Pinus radiata D. Don.), olive (Olea europaea L. cv. Manzanillo) and eucalyptus (Eucalyptus globulus Labill). Shoot elongation was inhibited in all three species, but sensitivity to the treatment varied.
Abstract
Watermelon [Citrullus lanatus (Schrad.) Matsum. & Nakai] seeds of the tetraploid ‘Alena’ and the diploid ‘Sugar Baby’ were subjected to one of several treatments prior to germination at 17°, 21°, and 25°C, including lateral splitting, soaking in H2O (aerated or nonaerated), GA4+7, or benzyladenine (BA) for 24 hr, or in KNO3 for 5 days, followed by drying. These treatments were successful in increasing germination percentage of ‘Alena’ seeds. Soaking treatments increased ‘Alena’ embryo length. ‘Alena’ seeds possessed thicker seed coats, larger seed cavities, and absorbed more water than those of their diploid counterpart, ‘Sugar Baby’.
Abstract
A new formulation of maleic hydrazide (Royal Slo-Gro), containing the surfactant polyoxyethylene trimethylnonyl ether (TMN-10), was superior to the maleic hydrazide formulation, containing polyoxyethylene nonyl surfactant (X-77) for inhibiting shoot elongation of Pinus radiata L., Xylosma congestum (Lour.) Merr., Viburnum japonicum (Thunb.) Spreng., and Coprosma repens A. Rich. The X-77 formulation was superior to the one containing TMN-10 for inhibiting growth of Juniperus sabina L. ‘Tamariscifolia’, Pyracantha coccinea (Roem.), and Callistemon citrinus (Curt.). There was little difference between the two formulations in tests with Cotoneaster pannosa (Franch.) and mixed results were obtained with Nerium oleander L. The greatest advantage of the TMN-10 formulation was manifested in Pinus where inhibition occurred without severe foliar discoloration, necrosis, or tip dieback which are characteristic of other maleic hydrazide formulations.