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  • Author or Editor: Charles H. Peacock x
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Initial release of N from waste materials used as natural organic N carriers for turfgrass may be slow due to the need for microbial degradation. In a greenhouse study, `Rebel' tall fescue (Festucau arundinacea Schreb.) and `Tifway' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] growth response to a natural organic fertilizer (Turf Restore) amended or not amended with a soil-derived microbiological inoculum were compared with soluble urea using sterilized and nonsterilized soil. No interactions of soil sterilization and fertilizers were noted at 19 days after treatment (DAT). Urea fertilizer increased tall fescue growth rates by 68% in the nonsterilized soil and 126% in the sterilized soil compared to rates for turf grown with inoculated Turf Restore. Nitrogen uptake rate was 419% higher with urea-fertilized turf in the sterilized soil than for turf fertilized with inoculated Turf Restore. Soil sterilization at 33 DAT no longer affected turf response, but turf growth rate was 133% higher and N uptake 353% higher with urea fertilization than with inoculated Turf Restore. Infection of the plants with Rhizoctonia spp. at 72 DAT was unaffected by fertilizer treatments. Bermudagrass response was similar to that of tall fescue. Growth rate was 67% and N uptake 51% higher with urea than with Turf Restore through 17 DAT, regardless of inoculant addition. Amendment of the natural organic fertilizer Turf Restore with a soil-derived biological inoculant did not enhance turf growth rate or N uptake nor impact infection with Rhizoctonia spp.

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Grass clippings may comprise a minimum of 35% of yard waste. We investigated whether bioavailable herbicide residues in grass clippings used as mulch would be toxic to desirable plants. In each of three experiments, tall fescue (Festuca arundinacea Schreb.) was treated with a mixture of 2,4-D + dicamba + MCPP at 0.5 g total a.i./m2. Clippings were collected at 1-, 5-, 10-, and 15-day postspray intervals. Clippings at gram equivalent weights relative to desired mulching depths were applied to tomato (Lycopersicon esculentum L.), cucumber (Cucumis sativus L.), salvia (Salvia splendens F.), and marigold (Tagetes tenuifolia Cav.) grown in pots. Plant dry-weight comparisons were made at two destructive harvest intervals, from 2 to 5 weeks after mulching. No mulch and nontreated mulch treatments were used as controls. Growth of tomato and marigold was enhanced when nontreated grass mulch was used compared to no mulch, but growth of cucumber and salvia was not enhanced. The bioavailable residues relative to the postspray interval (1 to 15 days) influenced growth of all species. Mulching depth affected growth of all species, except salvia. Herbicide-treated mulch reduced dry weight by ≤80% for cucumber, 73% for tomato, 65% for marigold, and 34% for salvia compared to controls. Herbicide residues apparently increased with mulching depth, resulting in a cumulative effect inhibiting plant growth. Chemical names used: 2,4-dichlorophenoxyacetic acid (2,4-D); 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP); and 3,6-dichloro-o-anisic acid (dicamba).

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Organic-(muck) and mineral-(sand) grown sods of ‘Floratam’ St. Augus tinegrass [Stenotaphrum secundatum (Walt.) Kuntze] were planted on 27 Apr. 1982. Two fertilizer rates (5 g N m-2 and 10 g N m-2) were applied before planting (sodbed surface) or after planting (sod surface). Rooting strength and turf quality were evaluated at 2 and 4 weeks, and growth rate at 4 weeks postplanting. Mineral-grown sod had greater rooting strength at 2 and 4 weeks after planting. Fertilizer placement was a factor only at 4 weeks, with sod surface better than sodbed placement. Strongest rooting occurred at 5 g N m-2. Turf quality and growth rate were greatest for organic-grown sod whereas the 10 g N m-2 fertilizer rate produced the best quality and greatest growth rate.

Open Access

Winter-hardiness of zoysiagrass (Zoysia spp.) cultivars is an important attribute throughout the biogeographical transition zone; thus, the inability to withstand freezing temperatures may limit the use of these cultivars. The objective of this research was to determine the freeze tolerance (LT50) of nine zoysiagrass cultivars grown in Raleigh, NC. Four Zoysia japonica Steud. cultivars (JaMur, Palisades, Empire, and Ultimate) and five Zoysia matrella (L.) Merr. cultivars (Pristine, Zeon, Cavalier, Diamond, and Zorro) were chosen to undergo freeze testing. Cores were taken from the field in Feb. 2008, 2009, and 2010 for the winter trials and in Apr. 2008, 2009, and 2010 for the spring trials (after green-up had occurred). The cores were subjected to freeze treatments of –6, –8, –10, –12, and –14 °C in programmable freezers. After thawing, cores were placed in a 41/20 °C greenhouse to promote green-up. Cores were rated for green-up after 4 weeks on a 1 to 9 scale. Nonlinear regression analysis was used to calculate an LT50 value for each cultivar. ‘JaMur’, ‘Palisades’, ‘Empire’, and ‘Ultimate’ were no different in the winter trials with an LT50 ranging from –9.8 to 10.2 °C. Among the matrella species, ‘Zeon’, ‘Cavalier’, and ‘Zorro’ were no different but ‘Diamond’ (LT50 of –6.0 °C) and ‘Pristine’ (LT50 of –5.7 °C) had less tolerance to freezing than the other matrella cultivars (LT50 range from –9.7 to –9.8), suggesting lower ability to cold-acclimate in the field than the other cultivars. Shoot weights of cores were correlated to visual green-up ratings for each cultivar with an R 2 range from 0.70 to 0.99 indicating a good relationship between the green-up ratings and shoot weights.

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