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  • Author or Editor: James McCrimmon x
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The Introduction to Horticulture course in the Department of Agriculture at Southeast Missouri State Univ. provides an overview of the principles of various horticulture crops. It is a lower-level course comprised primarily of freshmen and sophomores. Although many of the students that take the course are majors in the horticulture option, there are some students taking the course that are not horticulture majors, since the course is a requirement for all majors in the department. The objective of this study was to have students assess their knowledge of various types of horticultural plants before and after the course. During the first day of class, a pre-course student profile and survey was given to each student in order to determine their background and to assess their knowledge of certain horticultural plants. They were asked their knowledge of these topics; and, they rated their knowledge as follows: excellent, good, average, fair, or poor. Throughout the semester, these topics and plants were discussed or demonstrated in either the lecture or the laboratory. At the end of the semester, students were given a post-course survey to assess their knowledge of the same topics and horticultural plants which they rated their knowledge of the first day of class. Comparisons between pre- and post-course student assessment of their knowledge of topics and plants will be discussed.

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Limited information is available concerning the mineral nutrient content of different turfgrass species. There is a need to develop sufficiency ranges for turfgrasses under various management programs. The nutrient concentration of a turfgrass provides an indication of the nutrient status and quality of the turf. A study was conducted to assess the mineral nutrient composition of selected turfgrass species and cultivars. Plant tissue samples of the following turfgrasses were collected: creeping bentgrass, Agrostis palustris Huds. `Penncross'; bermudagrass, Cynodon dactylon (L.) Pers. `NuMex Sahara', `Santa Ana', `Texturf 10', and Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy `Tifgreen', `Tifway'; perennial ryegrass, Lolium perenne L. `Medalist × Blend'; St. Augustinegrass Stenotaphrum secundatum (Walt.) Kuntze `Seville'; and zoysiagrass, Zoysia japonica Steud. `El Toro' and Zoysia japonica × Zoysia tenuifolia Willd. ex Trin. `Emerald'. Three samples of each cultivar were collected, washed with deionized water for 30 s, and dried in a forced-air oven at 70°C for 72 hr. Plant samples were analyzed for both macronutrient and micronutrient concentration. For the bermudagrass cultivars, the concentrations of potassium (K) and magnesium (Mg) were less than 20.0 g·kg-1 and 2.0 g·kg–1, respectively, and less than known sufficiency levels. `Tifway' and `Texturf 10' had lower nitrogen (N) concentrations than other bermudagrasses. `Penncross' and `Medalist X' had the highest N concentrations. Zoysiagrass had low concentrations of N, phosphorus (P), calcium (Ca), K, and Mg. The concentration of copper (Cu) was low for zoysiagrass and three bermudagrass cultivars (`Texturf 10', `Tifgreen', and `Tifway'). There were differences among the turfgrasses for manganese (Mn) and zinc (Zn) concentrations.

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Establishing and maintaining turfgrass in the shade is one of the most challenging problems facing turfgrass managers and home owners. A greenhouse study was initiated to determine the shade tolerance of centipedegrass [Eremochloa ophiuroides (Munro.) Hack.], carpetgrass [Axonopus affinis Chase], and selected St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] cultivars (`Floratam', `FX-10', `Seville', and `TR 6-10'). Plants were grown under artificial shade (85% polypropylene shade cloth) and full sun. Actual percent shade (%shade={PAR under shade/PAR under sun}*100) was determined by measuring photosynthetically active radiation (PAR) under shade cloth and full sun adjacent to the shade structure using a quantum sensor. Pots were arranged in a completely randomized block design with four replications. All turfgrasses, except `TR 6-10', had a significant reduction in total dry weight in the shade compared to those in the sun. `TR 6-10' had the highest root, leaf, and total dry weight in the shade. `FX-10' had the lowest root, leaf, and total dry weight in the shade. Plants grown under the shade treatment compared to those in the sun resulted in an average decrease in stolon number of 13 and in total stolon length of 170 cm. In the shade, `Floratam' and `Seville' had the longest stolon internode lengths, while `Floratam' had the longest in the sun. There were significant differences for leaf length between the shade and sun treatments, except for carpetgrass and `FX-10'. `Floratam' and `FX-10' had differences in leaf width between the sun and shade.

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An experiment to determine the nonstructural carbohydrate composition and nodal survival (LT50) of common carpetgrass was conducted between 1993 and 1994 at Baton Rouge, La. Nonstructural carbohydrates in stolons were primarily sucrose [70-130 mg·g-1 dry weight (DW)] and starch (8-33 mg·g-1 DW). Total nonstructural carbohydrate (TNC) composition of stolons ranged between 30 to 165 mg·g-1 DW. Node survival following exposure to 2 °C ranged from 0% in August-sampled grass to 48% in December. The LT50 following acclimation under field conditions was -2 to -4 °C. Environmental factors influenced nonstructural carbohydrate composition, partitioning, and node survival. No relationship between TNC concentration and low-temperature tolerance was found. This research confirms previous reports that low-temperature tolerance of carpetgrass is very poor, and its culture may be limited to geographical areas having moderate winter temperatures.

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Four warm-season grass species [common carpetgrass (Axonopus affinis Chase), common bermudagrass (Cynodon dactylon [L.] Pers.), St. Augustinegrass (Stenophrum secondatum Walt. Kuntze.), and zoysiagrass (Zoysia japonica Steud.)] were established in containers filled with an Olivia silt loam soil for 12 weeks. Grasses were maintained weekly at 5 cm prior to the start of the experiment. Water stress treatments consisted of a control (field capacity), waterlogged, and flooded treatments. Waterlogging and flood treatments were imposed for a period of 90 days. The effects of water stress was dependent on grass species. Bermudagrass vegetative growth and turf quality were significantly reduced when flooded. Carpetgrass, St. Augustingrass, and zoysiagrass quality and vegetative growth were also reduced by flooding. St. Augustinegrass and zoysiagrass root dry weight was significantly decreased. Zoysiagrass plants did not survive 90 days of flooding. Leaf tissue analysis for common carpetgrass, common bermudagrass, St. Augustinegrass, and zoysiagrass indicated that plants subjected to waterlogging and flooding had significantly elevated Zn concentrations.

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Common carpetgrass (Axonopus affinis Chase), mowed at 3.8 or 7.6 cm and fertilized with at least 98 kg·ha–1 N, maintained acceptable lawngrass quality during the 1993 and 1994 growing seasons. Cumulative vegetative growth (CVG) quality and coverage were increased in mowed plots fertilized with 98, 147, or 196 kg·ha–1 N. Unsightly seedheads were a problem in nonmowed plots 3 weeks after the start of the experiment, but did not appear in the mowed plots. Our results indicate that mowing common carpetgrass at 3.8 or 7.6 cm and fertilizing with 98, 147, or 196 kg·ha–1 N will provide acceptable turfgrass quality.

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Field studies were performed on established carpetgrass (Axonopus affinis Chase) in 1994 and 1995 to evaluate plant growth regulators (PGRs) and application rates. Trinexapac-ethyl (0.48 kg·ha-1) improved turf quality and reduced cumulative vegetative growth (CVG) of unmowed and mowed plots by 38% and 46%, respectively, in 1995, and suppressed seedhead height in unmowed turf by >31% 6 weeks after treatment (WAT) both years. Mefluidide (0.14 and 0.28 kg·ha-1) had little effect on carpetgrass. Sulfometuron resulted in unacceptable phytotoxicity (>20%) 2 WAT in 1994 and 18% phytotoxicity in 1995. In 1995, sulfometuron reduced mowed carpetgrass CVG 21%, seedhead number 47%, seedhead height 36%, clipping yield 24%, and reduced the number of mowings required. It also improved unmowed carpetgrass quality at 6 WAT. Sethoxydim (0.11 kg·ha-1) suppressed seedhead formation by 60% and seedhead height by 20%, and caused moderate phytotoxicity (13%) in 1995. Sethoxydim (0.22 kg·ha-1) was unacceptably phytotoxic (38%) in 1994, but only slightly phytotoxic (7%) in 1995, reduced clipping yields (>24%), and increased quality of mowed carpetgrass both years. Fluazasulfuron (0.027 and 0.054 kg·ha-1) phytotoxicity ratings were unacceptable at 2 WAT in 1994, but not in 1995. Fluazasulfuron (0.054 kg·ha-1) reduced seedhead height by 23% to 26% in both years. Early seedhead formation was suppressed >70% when applied 2 WAT in 1994, and 43% when applied 6 WAT in 1995. The effects of the chemicals varied with mowing treatment and evaluation year. Chemical names used: 4-(cyclopropyl-x-hydroxy-methylene)-3,5 dioxo-cyclohexane-carboxylic acid ethyl ester (trinexapac-ethyl); N-2,4-dimethyl-5-[[(trifluoro-methyl)sulfonyl]amino]phenyl]acetamide] (mefluidide); [methyl 2-[[[[(4,6-dimethyl-2-pyrimidinyl) amino]carbonyl] amino] sulfonyl]benzoate)] (sulfometuron); (2-[1-(ethoxyimino)butyl-5-[(2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one) (sethoxydim); 1-(4,6-dimethoxypyrimidin-2yl)-3-[(3-trifluoromethyl-pyridin 2-yl) sulphonyl] urea (fluazasulfuron).

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