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Joanna Hubbard and Ted Whitwell

Ornamental grasses are popular landscape plants and often encounter turf encroachment or other grass weed problems. Several postemergence grass herbicides are available for use in turf and ornamentals and herbicide tolerance information is needed for ornamental grass species. Fifteen ornamental grasses including species from the genera Calamagrostis, Cortaderia, Eragrostis, Erianthus, Miscanthus, Sorghastrum, Spartina, Panicum and Pennisetum were field planted in Clemson, SC in May 1989 and Festuca species in November, 1989. Herbicide treatments were fenoxaprop-ethyl, fluazifop-P and sethoxydim at 0.4 kg a.i.·ha-1 applied 4 weeks after planting and an untreated control. Height and injury evaluations were taken at weekly intervals and plants were harvested 10 weeks after treatment. Fenoxaprop-ethyl treated Calamagrostis and Festuca species treated with all herbicides were the only treatments that were the same as untreated controls in terms of % injury, height and dry weight. Three ornamental Calamagrostis species were evaluated in a greenhouse study to determine the level of tolerance to fenoxaprop-ethyl at 0.4, 0.8, 1.6 and 3.2 kg a.i.·ha-1. No visual injury symptoms were seen on any treatments as compared to untreated controls but growth rates of the youngest leaves did vary among species shortly after treatment.

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Joanna Hubbard and Ted Whitwell

Twelve ornamental grasses from the genera Calamagrostis, Cortaderia, Eragrostis, Erianthus, Miscanthus, Sorghastrum, Spartina, Panicum, and Pennisetum were evaluated for tolerance to the postemergence herbicides fenoxaprop-ethyl, fluazifop-P, and sethoxydim at 0.4 kg a.i./ha. Calamagrostis was uninjured by fenoxaprop-ethyl as measured by visual injury ratings, height, and foliage dry weight. Greenhouse studies evaluated the tolerance of three Calamagrostis cultivars to fenoxaprop-ethyl rates of 0.4 to 3.2 kg a.i./ha with no observed visual injury from any treatment. However, the expansion rate of the youngest Calamagrostis leaf was reduced linearly with increasing herbicide rates each day after application. The highest rate (3.2 kg a.i./ha) reduced the leaf expansion rate by 1 day and all other rates by 3 days after treatment. Leaf expansion rate differed between Calamagrostis cultivars at different times after herbicide treatment. Dry weight of Calamagrostis arundinacea `Karl Foerster' was reduced at 4 weeks after treatment but not at 10 weeks after treatment. Chemical names used: (±)-ethyl 2-[4-[(6-chloro-2-benzoxazolyl)oxy)phenoxy]propanoate (fenoxaprop-ethyl); (R)-2-[4-[[5-trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid (fluazifop-P); 2[1-(ethoxy imino)butyl]-5[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim).

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Joanna Hubbard and Ted Whitwell

Ornamental grasses are popular landscape plants and often encounter turf encroachment or other grass weed problems. Several postemergence grass herbicides are available for use in turf and ornamentals and herbicide tolerance information is needed for ornamental grass species. Fifteen ornamental grasses including species from the genera Calamagrostis, Cortaderia, Eragrostis, Erianthus, Miscanthus, Sorghastrum, Spartina, Panicum and Pennisetum were field planted in Clemson, SC in May 1989 and Festuca species in November, 1989. Herbicide treatments were fenoxaprop-ethyl, fluazifop-P and sethoxydim at 0.4 kg a.i.·ha-1 applied 4 weeks after planting and an untreated control. Height and injury evaluations were taken at weekly intervals and plants were harvested 10 weeks after treatment. Fenoxaprop-ethyl treated Calamagrostis and Festuca species treated with all herbicides were the only treatments that were the same as untreated controls in terms of % injury, height and dry weight. Three ornamental Calamagrostis species were evaluated in a greenhouse study to determine the level of tolerance to fenoxaprop-ethyl at 0.4, 0.8, 1.6 and 3.2 kg a.i.·ha-1. No visual injury symptoms were seen on any treatments as compared to untreated controls but growth rates of the youngest leaves did vary among species shortly after treatment.

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Gary R. Bachman and Ted Whitwell

Demand for commercially grown Uniola paniculata L. (southern seaoats) is increasing for use in restoring beaches damaged by tropical storms. Fresh seeds harvested from the Jekyll Island, Ga area (with permission of the Jekyll Island Authority), were planted in 50 peat: 50 perlite and treated with 100 or 500 ppm GA4 for 24 h. Germination was higher for 100 compared to 500 ppm GA4. Liners grown from seed and planted with the crowns even with the surface of the pine bark-sand media, compared to deep planting to simulate burial conditions of beach planting, had the highest shoot and root weights after 100 days. Uniola paniculata liners with the crowns buried had reduced weights due to higher moisture conditions in the bottom of the containers. Uniola paniculata grown without supplemental fertilization had shoot weights similar to those of plants receiving 1.5 lb N/yd3 (0.89 kg N/m3) from both quick or slow release fertilizers. Increasing N to 3 lb/yd3 (1.78 kg N/m3) and/or supplying micronutrients only, reduced shoot weight. Nursery production of Uniola paniculata in pine bark-sand is one way to increase the supply of this important dune plant.

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F. C. Waltz and Ted Whitwell

Herbicides can runoff during storms or irrigation and contaminate ponds that are used for irrigation. Overseeded turf areas are particulary vulunerable to low concentrations of herbicides in irrigation water. A greenhouse study was conducted to determine the phytotoxic concentration of simazine in irrigation water perenial ryegrass (Lolium perenne), creeping bentgrass (Agrostis palustris), and fine fescue (Festuca rubra). Irrigation of 6.5 mm of herbicide contaminated and uncontaminated water was applied to seeded pots during a six week period. Concentrations of water containing simazine levels of 0.0001. 0.01, 0.1 and 1.00 ppm were used. Visual injury and number of live seedlings were evaluated every seven days after the beginning of the treatments and a threshold concentration was determined. An immunoassay kit was evaluated for practicality to the golf industry. Species varied in their response to simazine concentrations and immunoassay diagnostic kits have potential for use in detecting phytotoxic simazine concentrations.

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Gary R. Bachman and Ted Whitwell

Southern seaoats (Uniola particulata) are difficult to propagate from seed due to low seed numbers produced and cold dormancy effects. To efficiently produce southern seaoats in the nursery industry the dormancy must be effectively broken to assure quick and even germination. 24 hr soaks in gibberillic acid (100 and 500 ppm) or scarification of the seed coat combined with GA soaks were compared. Seeds were planted in 50/50 peat/perlite medium 2.5 cm deep. 21 DAT both the 100 and 500 ppm GA soaks had higher germination rates. The 100 ppm GA was determined to he most effective (56% germination) with the seedlings being 3 cm in length. The 500 ppm treated seeds were 6 cm in length hut twisted from the GA causing excessive cell elongation.

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Gary R. Bachman and Ted Whitwell

Bittercress (Cardamine hirsuta) is a nuisance weed in the ornamental nursery industry. Seed formation and dispersal during propagation production at an ornamental nursery were studied. There is much variability in silique number and seed per silique with the means being 77 and 29. respectively after five weeks. Average number of seed produced was 2233 per plant. The seeds arc forcefully expelled with a mean distance of 61 cm. Germination of these freshly released seeds was 90% after 13 days with a generation time of nine weeks. Seed source in the nursery was from either the gravel floor or reuse of the propagation containers. Comparing germination of bittercress seedlings in dirty or cleaned containers, use of dirty containers resulted in significantly higher numbers of bittercress seedlings than the cleaned.

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Anne Marie Johnson and Ted Whitwell

Twenty-nine annual and perennial wildflower species were evaluated for sod development based on ratings for appearance, root mat density, and stability following undercutting and storage and performance after replanting. Species selection was based on the lack of a large taproot, adaptability to the southeastern climate, flowering period, and potential for surviving root undercutting. Species were seeded in fall and spring, and leaf area and root mass samples were compared. Wildflower sod was undercut at a 5 cm (2 in) depth in March (fall-seeded plots) and May (spring-seeded plots) and then stored on clear plastic for 7 weeks and replanted. Fall-planted species had a higher survival rate than spring-planted species. Species selected for sod development were Achillea millefolium L., Chrysanthemum leucanthemum L., Coreopsis lanceolata L., Coreopsis tinctoria Nutt., Gaillardia aristata Foug., Monarda citriodora Cerv. ex Lag., Rudbeckia hirta L., and Verbena tenuisecta Briq. To reduce damage to aerial growth during harvesting, paclobutrazol, daminozide, and uniconazole were tested on eight greenhouse-grown wildflower species. Uniconazole had limited growth control over Rudbeckia hirta, Monarda citriodora, Coreopsis lanceolata, and Coreopsis tinctoria.

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Anne Marie Johnson and Ted Whitwell

Twenty-nine annual and perennial wildflower species were evaluated for commercial seed production potential in South Carolina. Species selection was based on adaptability to southeastern conditions and potential for use in wildflower sod. Potential for seed production was based on seed maturation ratings, percent germination 4 to 6 weeks after harvest, and yield. Individual species were seeded into I-m2 plots (3.3 ft2), on 7 Oct. Seeds were collected, clcaned, and counted, and total seed yield (lb) was calculated based on seed germination and weight of 100 seeds. Species with potential for production were Hesperis matronalis L. (2605 lb/acre), Monarda citriodora Cer. ex Lag. (1247 lb/A), Silene armeria L. (1122 lb/acre), Bidens aristosa (Michaux) Britton. (41 lb/acre), Centaurea cyanus L. (823 lb/acre), Coreopsis tinctoria Nutall (185 lb/acre), Gypsophila elegans L. (120 lb/acre), Ipomopsis rubra (L.) (2301 lb/acre) Wherry, and Rudbeckia hirta L. (500 lb/acre).

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Anne Marie Johnson and Ted Whitwell

In a study examining the potential for production of a field grown wildflower sod, 29 annual and perennial wildflower species were evaluated. Species selection for the study was based on lack of a large taproot, adaptability to the southeastern climate, flowering period, and potential for surviving root undercutting. Species were individually seeded in 1-m2 plots in Fall 1993 and Spring 1994 to determine an optimum planting time. In early Spring 1994, fall seeded plots were undercut at a 5 cm depth with a hand held sod cutter. Spring planted species were undercut in early summer. After undercutting, sod pieces were placed on clear plastic under overhead irrigation for 7 weeks then transplanted to prepared field sites. Ratings for flower appearance, root mat density, top growth vigor and fresh root weights were taken at the time of undercutting and after transplanting. Fall-planted species had a higher survival rate than spring-planted species. Species with the highest ratings and greatest increase in fresh root weights from the time of undercutting to transplanting were yarrow (Achillea millefolium), oxeye daisy (Chrysanthemum leucanthemum), lance-leaf coreopsis (Coreopsis lanceolata), plains coreopsis (Coreopsis tinctoria), blanketflower (Gaillardia aristata), lemon mint (Monarda citriodora), blackeyed Susan (Rudbeckia hirta), and moss verbena (Verbena tenuisecta).