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  • Author or Editor: James Aldrich x
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Postemergence control of Phyllanthus urinaria L. (chamberbitter) in nursery and landscape plantings has been primarily limited to hand-weeding. Prodiamine was evaluated for postemergence control of chamberbitter and phytotoxicity to containerized ornamentals. On 20 June 1995, prodiamine at 0, 1.68, 3.36, or 6.72 kg a.i./ha was applied over-the-top to immature chamberbitter growing in 3.8-L containers of established Buddleia davidii Franch. `White Bouquet' Cuphea hyssopifolia HBK. `Desert Snow', Lantana camara L. `Irene', and Lantana montevidensis (Spreng.) Briq. `Lavender Weeping'. Weed-free checks were included. Applications were made with a compressed air backpack sprayer. There were four replications per treatment placed in a randomized complete block design by species. Plants were established and maintained on a container bed under full sun and overhead irrigation. Growth of and phytotoxicity to the ornamentals species, and percent coverage and number of chamberbitter, were recorded periodically for 14 weeks after treatment (WAT). Chamberbitter shoots were harvested for dry weight analysis 14 WAT. Prodiamine provided some postemergence control of chamberbitter. However, Cuphea and both Lantana species exhibited leaf distortion and/or delayed flowering.

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The response of the root system of `Barbara Karst' bougainvillea [Bougainvillea buttiana (Bougainvillea glabra Choicy × Bougainvillea peruviana Humb. & Bonpl.) `Barbara Karst'] cuttings to 100 g Cu(OH)2·liter-1 in a white latex paint applied to the interior surface of square 66 ml, 120 ml, or 280 ml plastic pots was determined. Cuttings (10 cm long; 3-5 nodes; 2 leaves) were scored on opposite sides and dipped in 6000 mg·liter-1 KIBA for 3 sec. The cuttings were placed in treated or untreated pots that contained a medium of 1 Canadian sphagnum peat: 1 coarse perlite (v/v). The pots were completely randomized in a 3×2 factorial design. The cuttings were rooted under intermittent mist 9 sec·min-1 for 12 hr·day-1 in a greenhouse (20% shade). The number of primary roots, fresh and dry weights, and root quality were determined 15 June. The Cu(OH)2-treated pots resulted in a more compact, well-branched root system and eliminated root circling. However, root fresh weight was reduced by Cu(OH)2 treatment. Pot size influenced the number of primary roots and fresh and dry weights.

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The effectiveness of three concentrations of either dikegulac-sodium or mefluidide on the growth of two containerized woody vine crops was investigated. A single application of dikegulac-sodium at 1600, 3200, or 4800 mg·liter-1 or mefluidide at 600, 1200, or 1800 mg·liter-1 was applied to either 3.8-liter containers of Asiatic jasmine (Trachelosoerum asiacticum Siebold and Zucc.) or staked confederate jasmine (Trachelosperum jasminiodes (Lindl.) Lem.) on 25 May 1993. Two additional applications were made at 8 week intervals after transplanting to 9.5-liter containers. Plant growth and phytotoxicity were evaluated 0, 4, and 8, and 1, 2, 4, and 8 weeks after application, respectively. Dikegulac-sodium at 3200 mg·liter-1 was the optimum treatment for suppressing the lateral growth of Asiatic jasmine and the vertical growth of confederate jasmine with minimal phytotoxicity. Dikegulac-sodium at 4800 mg·liter-1 excessively inhibited growth of both species and resulted in unacceptable phytotoxicity. All mafluidide treatments had minimal growth inhibitory effect on either species.

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The effect of four PGRs on production of `Barbara Karst' bougainvillea [Bougainvillea × buttiana (Bougainvillea glabra Choicy × Bougainvillea peruviana Humb. & Bonpl.) was determined. Liners were transplanted into 3.8-L containers with a soilless substrate on 6 Apr. 1995 and were pruned on 15 May (mean height and width 23.6 and 34.5 cm, respectively). Uniconazole (10 ppm), maleic hydrazide (2808 ppm), daminozide (5000 ppm), and paclobutrazol (50, 100, or 200 ppm) were applied as a foliar spray (to wet) by a compressed air backpack sprayer on 16 May (0 weeks after treatment [WAT]). Daminozide (5000 ppm) was reapplied 31 May and 13 June as described above. Soil drenches of 5, 10, or 20 ppm paclobutrazol were additional treatments. Two nonPGR-treated controls were included: pruned at 0 WAT, and pruned at 0 and 4 WAT. There were eight replications per treatment placed in a randomized complete block design on a container bed under full sun and drip irrigation. At 6, 9, and 12 WAT, growth, flowering, growth habit, number of structural branches (>15 cm long), and level of bacterial spot infection by Pseudomonas andropogonis were recorded. Marketability was recorded 12 WAT and phytotoxicity noted 1, 4, 5, 6, 9, and 12 WAT. No PGR treatment effectively suppressed growth, or enhanced quality or marketability of `Barbara Karst' bougainvillea grown in 3.8-L containers. Furthermore, daminozide reduced the number of structural branches and maleic hydrazide was phytotoxic.

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The parasitic eastern mistletoe, Phoradendron serotinum is a perennial evergreen that infests trees including the deciduous pecan [Carya illinoensis (Wangenh.) C.Koch]. Various chemical and/or mechanical methods of mistletoe eradication have been studied. An efficient method of mistletoe removal in deciduous trees involves the use of ethephon, an ethylene-releasing compound. Mistletoe in dormant `Stuart' trees and `Desirable' trees at bud break were treated on 15 Mar. with 0, 2500, 5000, 7500, or 10,000 ppm ethephon [pH of treatment solution adjusted with 1.2 ml/L of a buffering agent (pH +, Stoller Chemical Co.)]. `Desirable' trees at the prepollination stage of development were treated with 0, 312, 625, 1250, or 2500 ppm + 1.2 ml/L of the buffering agent on 27 Mar. 1991. All ethephon treatments except 312 and 625 ppm resulted in >95% defoliation on 18 Apr. All chemical treatments resulted in abscission cf some mistletoe branchlets. There was a negative correlation between ethephon concentration and mistletoe regrowth on 2 Dec. for both cultivars. The most effective treatment was 2500 ppm applied at prepollination on `Desirable'. This treatment resulted in no mistletoe regrowth on 80% of the trees. No phytotoxicity to the pecans was observed.

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Dormancy issues and lack of approved protocols have led to increasing use of the pregermination tetrazolium test to assess whether seeds of premium-priced, prevariety germplasm of native wildflower species are living and have the potential to germinate and develop normally under field conditions, that is, whether seeds are viable. A major concern is the limited amount of industrywide training on how to conduct and interpret results of tetrazolium (TZ) tests for the multitude of native species. Precise methods that yield uniform results are especially critical for testing of prevariety germplasm of native species given their high value and economic consequences of inaccurate test results. In preliminary work, we observed that embryos extracted from intact seeds of native Coreopsis species subjected to TZ testing were viable if they were turgid and appeared normal and were stained pink, red, or were pure white with or without the radicle tip stained pink to red. In this study, we conducted an in-depth analysis of TZ testing of intact seeds of prevariety germplasm of four native Coreopsis species to: 1) verify our preliminary conclusions; and 2) to determine if staining could be improved by preconditioning or gibberellic acid (GA3) because relatively low percentages of embryos of intact seeds stained pink or red. In addition, we evaluated two other methods to assess viability: the excised embryo test and emergence tests in soil and a soilless medium under ambient conditions. We confirmed that embryos extracted from intact seeds subjected to TZ testing were viable provided that embryos were turgid and appeared normal and were stained pink, red, or were pure white ± a pink to red radicle tip. Embryo staining was not consistently improved by moist preconditioning or GA3. Results of pregermination TZ tests of intact seeds and/or germination plus postgermination TZ tests of intact, nongerminated seeds were not consistently accurate and/or uniform across all species and seed lots, issues usually encountered in seed lots that were relatively dormant or of poor quality, and in postgermination TZ testing of seed lots with relatively low dormancy. Moreover, these issues are likely to be encountered even with standard TZ testing protocols given the widely accepted challenges of accurately interpreting TZ tests of native species in general. The most precise, uniform method of assessing viability was the excised embryo germination test because all viable seeds germinated, results were easy to interpret so the likelihood of false-positives or -negatives was nil, and results were very uniform across replications. Emergence tests under ambient conditions substantially underestimated viability. In summary, the high cost of prevariety germplasm seeds of native Coreopsis species, inherent genetic and phenotypic variability, and unknown dormancy characteristics warrant the use of the embryo excision test for determining viability and for increased sample sizes, especially for any tests involving TZ.

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Application of plant biostimulants to various crops has enhanced yields and increased growth. This study was conducted to determine the effect of plant biostimulants on growth of Hemerocallis × `Aztec Gold'. Roots of single-plant divisions were immersed for 5 min in solutions of 520 ppm KELPAK (seaweed concentrate), 390 ppm PGR IV (hormone concentrate containing nutrients), 250 ppm AGRI-GRO (contains dormant nitrogen-fixing bacteria) + 250 ppm molasses, or water prior to planting on 20 April 1992. Plants were grown in 3.8-liter containers under 31% shade. Foliar sprays (to wet) of these biostimulants (same concentrations as before) were applied on 20 May, 19 June, and 13 August 1992. Plants were harvested on 21 October 1992. None of the biostimulants affected final plant height, number of divisions, or shoot and root fresh and dry weights. However, plants treated with KELPAK had higher shoot to root ratios (fresh and dry weight) compared to the control.

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Flowering of Bougainvillea is enhanced when liners are treated 0 and 4 weeks after transplanting and pruning with 1200 or 1600 ppm dikegulac (ATRIMMEC). Dikegulac, however, slightly to moderately reduces bract size. This study was conducted to quantify the effect of dikegulac on bract size. Rooted liners of Bougainvillea `Mauna Kea' were transplanted into 2.5-liter containers (1 liner/container) on 14 April (Expt. 1) or 20 August 1991 (Expt. 2) and pruned (0 weeks). Dikegulac at 0, 400, 800, 1200, or 1600 ppm was applied at 0 and 4 weeks. Control plants were also pruned at 4 weeks. Plants were grown under full sun. In Expt. 1, 400 ppm dikegulac reduced bract size about 25%, with 800 to 1600 ppm reducing bract size about 37%. However, dikegulac had little to no effect on bract size in Expt. 2 seemingly due to cool temperatures. The mean minimum and maximum temperatures were about the same during the first six weeks of both experiments; however, the mean minimum/maximum temperatures for the remainder of Expt. 1 and 2 were 19.2°/30.4° and 10.8°/23.2°C, respectively.

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Abstract

Methazole [2-(3,4-dichlorophenyl)-4-methy1-1,2,4-oxadiazolidine-3,5-dione] napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], oryzalin [3,5-dinitro-N4 ,N4 -dipropyl-sulfanilamide], oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-∆2-l,3,4-oxadiazolin-5-one], and simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] each at 4.5 kg/ha were applied preemergence on June 17, 1976 in a nursery of 6-month-old seedlings of peach [Prunus persica (l.) Batsch cv. Nemaguard]. Though simazine and oryzalin provided better weed control, oxadiazon increased seedling height and trunk diameter from 25 to 89 days after application. All treatments impeded bark adhesion (slippage) 25 days after application but not after either 56 or 89 days. No phytotoxicity was observed from any treatment.

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Profitability and production of hanging baskets of bougainvillea, a short day species, could increase if vegetative growth and flowering were more easily controlled. Three-month-old rooted liners of Bougainvillea `Barbara Karst' and `Rainbow Gold' were transplanted into 4.5-liter hanging baskets (3 liners/basket) in late April (Expt. 1) or late July 1991 (Expt. 2) and pruned 2 or 3 days later. Selected combinations of 0, 600, 800, 1200, or 1600 ppm dikegulac were applied at 0, 2, and 4 weeks after initial pruning. Control plants were also pruned at 4 weeks. Plants were grown under full sun. Peak flowering occurred 9 to 10 weeks after initial pruning in both experiments. Dikegulac enhanced flowering of both cultivars under increasing and decreasing daylengths but was greatest under increasing daylengths, especially for `Rainbow Gold'. There was little to no effect on branching.

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