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  • Author or Editor: Lih-Jyu Shu x
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Abstract

Foliar sprays of 0.5% dikegulac sodium applied to 4 cultivars of greenhouse-forcing azaleas (Rhododendron spp.) 11 days after shearing, decreased shoot length and increased shoot number with more shoots originating along the entire stem at lower node positions than on untreated plants. Five to 6 weeks after treatment shoot length increased normally indicating that dikegulac sodium did not have a long term depressive effect on azalea shoot growth and development.

Open Access

Abstract

Applications of 0.5% dikegulac sodium (sodium salt of 2,3:4,6-bis-0-(l-methylethylidene-L-xylo-2-hexulofu-ranosonic acid) sprays produced significantly more new shoots on ‘Red wing’ or ‘King fisher’ azalea plants than manual pinching and other chemical pinching agents in 2 experiments. In 5 other experiments involving 5 other cultivars, dikegulac sodium-treated plants generally produced the most shoots, however, the shoot number was not different from shoot number on either manually pinched or 4.2% Off-Shoot-O-treated (mixture of C6 to C12 methyl ester of fatty acids) plants. Sprays of dimethyl dodecylamine caprylate at 0.2% and 0.5%, n-decanol at 2.5%, ethephon [(2-chloroethyl)phosphonic acid)] at 0.08%, and UBI-P293 (2,3-dihydro-5,6-diphenyl-1,4-oxathiin) at 1.0% gave inconsisent results but yielded shoot number comparable to dikegulac sodium in some tests. Off-Shoot-O, dimethyl dodecylamine caprylate, and n-un-decanol were destructive pinching agents at some concentrations and caused considerable plant injury. Dikegulac sodium caused minor injury and transient chlorosis. Ethephon, PBA [6-benzylamino-9(2-tetrahydropyran-2-yl)-9H-purine], and UBI-P293 did not produce any visible phytotoxicities. Shoots of plants sprayed with 0.5% dikegulac sodium and 1.0% UBI-P293 were of similar length or shorter than shoots of either manually pinched or untreated check plants 3 weeks after treatment.

Open Access

Abstract

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.

Open Access