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Eight species of low-growing woody and herbaceous landscape plants were evaluated for tolerance to 1.1 or 2.2 kg a.i. bentazon/ha (plus a crop oil) applied over the top twice 7 days apart. Raphiolepis indica L. Lindl. `Alba' was the only species tolerant to bentazon in either of two experiments. Bentazon injury to Liriope muscari (Decne.) L.H. Bailey `Evergreen Giant' was minor (slight chlorosis) and would probably be tolerable under most landscape situations. Injury (primarily chlorosis/necrosis) to Carissa macrocarpa `Emerald Blanket', Juniperus horizontalis Moench `Bar Harbor', Pittosporum tobira (Thunb.) Ait. `Compacta Green', Trachelospermum asiaticum (Sie-bold & Zucc.) Nakai `Aslo', Ophiopogon japonicus (Thunb.) Ker-Gawl., and Hemerocallis × `Aztec Gold' was significant and therefore unacceptable. Chemical name used: 3-isopropyl-1H-2,1,3-benzothiadiazin-(4)-3H-one 2,2-dioxide (bentazon).
The possible loss of IBA for use in propagation of woody ornamental has prompted increased interest in the registration of phenyl indole-3-thiobutyrate (P-ITB), a potential alternative. Two products currently available, CYTOKIN and ROOTS, warrant investigation since ROOTS stimulates rooting of a few species (R. Poincelot, pers. comm.) and CYTOKIN is a similar product. Both contain naturally-derived cytokinin and algal extracts. The purpose of this study was to determine the rooting activity of these products utilizing the mung bean bioassay. Seeds of Vign a radiata `Texsprout' were sterilized in 0.5% sodium hypochlorite for 10 min, rinsed, aerated for 24 hr in tap water, and then sown in coarse vermiculite (1 cm deep) held in plastic trays. Growth of the seedlings and the bioassay were conducted in a growth chamber under a 16-hr photoperiod, an irradiance of 85 μE, 27.5°C during the day and 21.1 C at night. ROOTS enhanced rooting better than 0.1 mM NAA and was 68% that of 0.1 mM IBA. CYTOKIN at .2, 1, 2, 4, 5, or 10% did not stimulate rooting; additional concentrations are currently being tested.
Trees budded on the Brazilian rootstock `A-82' have a lower feeding preference by the primary vector of Phony peach disease over trees on `Nemaguard'; the southeastern industry standard rootstock. `A-82' budded trees have lower levels of infection of the xylem-limited bacteria Xylella fastidios a compared to `Nemaguard' budded trees.
The feasibility of using `A-82' in the industry was evaluated by budding `Flordaking' and `Flordaglobe' peach and `Sungem' and `Armking' nectarine to `A-82' and `Nemaguard'. Vegetative and fruiting responses of these trees will be discussed.
Abstract
Naphthaleneacetic acid (NAA) ethyl ester formulation at 0.25% plus 20% flat white latex paint applied to nonbearing peach [Prunus persica (L.) Batsch] tree trunks reduce sprouting, had no effect on tree growth, and did not induce gummosis.
Abstract
Vegetative and fruiting responses of peach [Prunus persica (L.) Batsch cv. June Gold] treated 3 years with glyphosate [N-(phosophonemethyl)glycine], applied at 2.2 and 4.4 kg/ha singly or in combination with 2.2 kg ai/ha simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] or oryzalin [3,5-dinitro-N4,N4-dipropylsulfanilamide], and a treatment of 0.6 kg ai/ha paraquat (1-1’-dimethyl-4,4’-bipyridinium ion) plus simazine or oryzalin were compared to trees in a hand cultivated control. Herbicide treatments resulted in increased trunk diameters and fruit set while glyphosate combinations resulted in improved yields.
Abstract
Paclobutrazol was applied 30 Mar. 1984 as a soil drench to 3rd-leaf pecan [Carya illinoensis (Wangenh.) C. Koch] ‘Cheyenne’ at concentrations between 0.05 to 2.60 g a.i./cm2 trunk cross-sectional area. Paclobutrazol inhibited tree growth, shoot extension, and trunk and limb growth during 1984 and 1985. Relative water content of leaflets was positively related and leaflet area was negatively related to paclobutrazol concentration. Paclobutrazol promoted lateral branching on a unit length basis on 1983 wood, although no significant relationship was apparent on 1984 wood. Leaflet weight under stress and turgid conditions was reduced with increasing paclobutrazol concentration. Net CO2 assimilation rate, leaf conductance, transpiration rate, leaf chlorophyll, and kernal weight measured during 1985 were not affected by paclobutrazol. The effects of soil-applied paclobutrazol under field conditions persist at least 3 years. Chemical name used: P-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
The use of dikegulac in production of hanging baskets (4.5-liter capacity) of Bougainvillea `Rainbow Gold' was investigated under decreasing daylengths and high temperatures. Liners treated with a single application of 1200 ppm dikegulac 4 weeks after transplanting and pruning (WATP) resulted in the only marketable hanging baskets 9 WATP. Application of 1200 ppm dikegulac 4 WATP enhanced flowering and aesthetic quality compared with plants that had only been pruned. Bract size did not appear to be reduced. Plant width tended to increase as time of application was delayed. Dikegulac had no effect on height or branching. Chemical name used: sodium salt of 2,3:4,6-bis-O-(l-methylethylidene)-a-L-xylo-2-hexulofuranosonic acid (dikegulac-sodium).
The use of dikegulac foliar sprays in production of 4.5-liter hanging baskets (25.4-cm in diameter) of `Barbara Karst' bougainvillea [Bougainvillea ×buttiana (Bougainvillea glabra Choicy X Bougainvillea peruviana Humb. & Bonpl.) `Barbara Karst'] and `Rainbow Gold' bougainvillea (Bougainvillea `Rainbow Gold') was investigated under high temperatures (27.5-32C) and two production seasons (late spring to early summer and midsummer to early fall). During the late production season, liners pruned at transplanting (0 weeks) and treated with 1600 mg dikegulac/liter at 0 and 4 weeks resulted in plants with more flowers than that of controls (pruned only at 0 and 4 weeks), with `Barbara Karst' having a slightly compact, pendulous growth habit similar to that of controls. Dikegulac enhanced flowering compared with controls during midspring to early summer, but it did not result in plants with a slightly compact pendulous growth habit. These results suggest that a foliar spray of 1600 mg dikegulac/liter could substitute for the second pruning during hanging basket production of `Barbara Karst'. Chemical name used: sodium salt of 2,3:4,6-bis-O-(1-methylethylidene)-α-xylo-2-hexulofuranosonic acid (dikegulac-sodium).
Foliar spray application of dikegulac at 1600 mg·liter-1 during production of Bougainvillea glabra Choicy `Mauna Kea White', and Bougainvillea `Raspberry Ice', `Royal Purple', `Summer Snow', and `Temple Fire' in 4.5-liter hanging baskets (25.4 cm in diameter) was investigated in relation to flowering. The effect of foliar-applied dikegulac at 0, 400, 800, 1200, and 1600 mg·liter-1 on bracteole size of `Mauna Kea White' was also determined. Liners of `Temple Fire' pruned at transplanting (0 weeks) and sprayed with dikegulac at, 0 and 4 weeks had increased flowering and a slightly more compact, pendulous growth habit than plants that had only been pruned at 0 and 4 weeks. Dikegulac had little to no effect on flowering of the other cultivars. Under late-spring to early summer conditions (generally increasing temperatures), bracteole size of `Mauna Kea White' was reduced ≈25 % by 400 mg dikegulac/liter compared to nontreated plants; 800 to 1600 mg dikegulac/liter reduced bracteole size ≈37%. Under late-summer to mid-fall conditions when the weather was cooler and wetter, dikegulac had little to no effect on bracteole size; however, bracteoles of nontreated plants were ≈25% smaller than those of plants grown under the warmer and drier conditions of late spring to early summer. Chemical name used: sodium salt of 2,3:4,6-bis -O- (1-methylethylidene) -α-l-xylo- 2-hexulofuranosonic acid (dikegulac).
Abstract
Dikegulac [2,3:4,6-bis-0-(1-methylethylidene)-a-L-xylo-2-hexulofuranosonic acid] was applied by handgun to the drip-point on May 27, 1978 at 0, 500, 1000, 1500, and 2000 ppm to trees of peach [Prunus persica (L.) Batsch cv. June Gold] 2 months after transplanting. Tree height and width decreased and lateral branching increased with increasing concentration of dikegulac. Phytotoxicity was concentration-dependent. All treatments were repeated on May 21, 1979, and a 3rd application of 500 and 1000 ppm was made on August 8, 1979. The best control of vegetative growth in 1979 was from biannual applications since foliar phytotoxicity was reduced. No effect on flowering date or number was detected in March 1980.