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  • Author or Editor: H. Hield x
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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.

Open Access
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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.

Open Access

Abstract

Painting of inhibitors on pruning cuts reduced growth only in the area proximal to treatment in Eucalyptus globulus Labill. Sprays of 0.2 to 0.3% 1-propylphosphonic acid (NIA 10656) or injection of 8 ml of 10% tech grade NIA 10656 gave shoot growth reduction for 1 year. Ethyl hydrogen 1-propylphosphonic acid (EHPP, NIA 10637) showed responses similar to NIA 10656. Naphthaleneacetic acid (NAA), EHPP, NIA 10656 and amonium ethyl carbamoylphosphonate (Krenite) all showed certain growth regulator responses when painted on pruning cuts. Inhibitors applied in an asphalt carrier to cuts were more effective than similar applications in a water carrier. Application of 6, hydroxy-3-(2H) pyridacinone (MH), trifluromethyl sulfonamido-p-acetotoluidide (Sustar), NAA and EHPP combination, or methyl 2-chloro-9-hydroxyfluorene-9-carboxylate (chlorfluernol methyl ester, principal active ingredient in Maintain CF 125) were tested as trunk bark bands for reduction in terminal shoot growth. The Maintain CF 125 product diluted with an equal amount of diesel oil and applied in a band equal to the trunk diameter of E. camaldulensis Denhardt effected a reduction in terminal growth 11 months after banding. Maintain CF 125 applied at full product strength (12.5%) or diluted equally with water and the other inhibitors tested did not cause growth reduction.

Open Access

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.

Open Access

Abstract

Sprays of a plant growth regulator ammonium ethyl carbamoylphosphonoate (Krenite), applied to top regrowth of mature Lisbon lemon trees [Citrus limon (L.) Burmann] resulted in significant inhibition of growth for over 1 year. At concentrations above 0.2% there was excessive foliar and small branch damage.

Open Access