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  • Author or Editor: Gregory L. Davis x
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In his State of the Union Address (1990), President Bush proposed planting a billion trees annually for the next 10 years. Organizations such as Global ReLeaf are planning to plant 400 to 600 million trees by the year 2000. A review of science education periodicals and general information available on tree planting and care reveal little directed to children. Science education tends to focus on the nature, not the handling of trees, and where planting ideas are suggested, they tend to be about growing trees from seed. To determine the level of landscape tree care knowledge of 4th–6th graders, a questionnaire addressing how trees grow, site and tree selection, proper planting, and other areas was administered by 4-H agents and Univ. of Florida students throughout the state during five camps, involving 211 children during the summer of 1995. The questionnaire was revised with additional topics such as irrigation and mulching added and administered during three 4-H camps involving 77 4th–6th graders. Answers to these questionnaires were used to develop materials targeted for this age group and their teachers.

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Osmoconditioning was examined as a presowing seed treatment for its influence on germination, rate of germination, and initial seedling root growth in seeds of A morpha fruticosa L. (imbibed for 48 hrs) and Hippophae rhamnoides L. (imbibed for 18 hrs) at 25C. Based on preliminary studies, seeds were imbibed in one of five osmotic solutions (0, -0.2, -0.7, -1.5, or -3.0 MPa) prepared with polyethylene glycol-8000. Seeds were then sown in test tubes containing plugs of Oasis growing medium saturated with osmotic solutions of no drought (0 MPa) or drought (-1.0 MPa) conditions at 15-35C. Root growth was measured with an image analysis system. Total root growth per seedling was less for both species in drought conditions regardless of temperature. Presowing treatments did not produce large differences in germination or rate of germination in either species.

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Municipalities often restrict irrigation of urban landscapes, causing plants to experience drought stress. Few data are available regarding drought resistance of non-turfgrass landscape species. This study evaluated the performance of one turfgrass (Poa pratensis L. ‘Apollo’) and eight herbaceous landscape species (Achillea millifolium L., Ajuga reptans L. ‘Bronze Beauty’, Liriope muscari Decne., Pachysandra terminalis Siebold and Zucc., Sedum album L., Thymus serpyllum L., Vinca major L., and Vinca minor L.) during a severe drydown and subsequent recovery. This greenhouse study was conducted in the spring/summer and again in the fall of 2010. S. album performed the best, averaging 254 days to decline to a drought rating of 1 (1 to 9 scale, 1 = dead/dormant and 9 = best quality). L. muscari and P. terminalis also performed well, averaging 86 days to a drought rating of 1. V. minor and V. major declined faster than the previous species, averaging 63 days. A. millifolium, A. reptans, P. pratensis, and T. serpyllum declined the fastest to a drought rating of 1 (mean 52 days). Thereafter, the only species to recover after 60 days of resuming irrigation were P. pratensis [46% pot cover (PC)], S. album (38% PC), and V. major (35% PC) in the spring/summer study; no species recovered during the fall study. Results indicate S. album, L. muscari, and P. terminalis are the most drought-resistant among the species evaluated in landscapes where severe drought may occur. V. minor and V. major are good selections in less severe droughts as is P. pratensis if periods of dormancy are acceptable.

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