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  • Author or Editor: Diane L. Johnston x
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`Pink Splash' Hyoestes were grown in chambers fitted with single-walled polycarbonate. Chambers were shaded with various photoselective shading compounds, using a white shading compound as a non-selective control. When grown under orange shading, plants had more shoot dry weight, greater leaf area, larger stem diameters, and were taller compared to plants shaded with white. When grown under green shading, plants had less shoot dry weight, less leaf area, smaller stem diameters, and were taller compared to plants shaded with white. Intermediate responses were recorded when plants were grown under red, blue or yellow shading. Differences in the ratio of red to far-red light among shading compounds did not provide a consistent explanation of growth responses.

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Stem tip cuttings of Evolvulus glomeratus Nees & Mart., E. tenuis Nees & Mart., Lantana camara L. `Dallas Red,' and L. montevidensis Briq. `Alba' were rooted for 6 weeks in 57-mm-diameter (150 ml) square pots. Before rooting, interior surfaces of half of the pots were treated with 100 g Cu(OH)2/liter, while remaining pots were left untreated. Elongation of adventitious roots stopped when root tips came in contact with a Cu(OH)2-treated surface. Cupric hydroxide treatment reduced total root length and the length of the longest root for all four species, but did not influence root, shoot, or total plant weight. One month after transplanting to 150-mm-diameter (1.2 liter) hanging baskets, plants moved from Cu(OH)2-treated pots had more flowers than those transplanted from nontreated pots. Applying Cu(OH)2 to interior surfaces of pots used for propagation prevented root deformation, reduced root length, and increased flowering following transplanting.

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The effect of Cu(OH)2 applied to interior container surfaces on shoot and root responses was evaluated on eight species cultivated in subtropical regions. Species studied were Cedrela odorata L.; Eriobotrya japonica (Thunb.) Lindl.; Leea coccinea Planch.; Peperomia serpens (Swartz.) Loud.; Peperomia obtusifolia (L.) A. Dietr.; Radermachera sinica (Hance) Hensl.; Schefflera actinophylla (Endl.) Harms; and Swietenia mahagoni (L.) Jacq. No foliar Cu toxicity symptoms developed on any species during the study. Swietenia mahagoni seedlings grew faster in height and had larger shoot: root ratios when grown in Cu(OH)2-treated containers than in nontreated containers. Leea coccinea seedlings were taller and produced more shoot dry weight when grown in Cu(OH)2-treated than in control containers. Applying Cu(OH)2 did not influence shoot growth of the other six species studied. Root coverage reduction on the exterior of the rootball in Cu(OH)2-treated containers was excellent for all species studied, and coverage was completely eliminated in three species. Shoot and root responses to Cu(OH)2-treated containers varied among subtropical species, which is consistent with shoot and root responses among temperate species.

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Phenoxy and related herbicides used in turfgrass have the potential for volatilization and movement from treated areas. Three studies assessed potential injury to subtropical landscape plants caused by volatile turf herbicides in polyethylene enclosures. Phenoxy herbicide mixtures were emphasized. There were significant differences among the seven landscape species tested. The most sensitive species were african marigold (Tagetes erecta), joseph's coat (Alternanthera ficoidea), and tomato (Lycopersicon esculentum). Severe injury was caused by exposure to herbicides containing 2,4-D isooctyl ester and MCPA isooctyl ester. Exposure to individual active ingredients 2,4-D dimethylamine, dicamba acid, atrazine, and metsulfuron resulted in no injury to the species tested.

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