yields with the exception of the SE × NS × NR interaction ( Table 4 ). Table 4. Results of variance analysis for turf color, turf quality, and clipping yields under seasons (SE), different nitrogen sources (NS), application time (AT), and nitrogen rates
Ugur Bilgili, F. Olcay Topac-Sagban, Irfan Surer, Nejla Caliskan, Pervin Uzun, and Esvet Acikgoz
Robert C. Hansen, Kenneth D. Cochran, Harold M. Keener, and Edward M. Croom Jr.
A natural product known as taxol has been approved by the FDA for treatment of ovarian and breast cancers. In addition, preliminary clinical studies have shown encouraging results when using taxol to treat melanomas, lung, head, and neck cancers. Ornamental yews have been identified as a potential renewable source of taxol and related taxanes. Commercial nurseries were surveyed during Summer and Fall 1991 as a basis for estimating populations of Taxus cultivars currently growing in the United States. Clippings of selected cultivars were sampled from nursery fields in Ohio and Michigan to estimate expected clippings yields as a function of cultivar and cultivar age. More than 30 million Taxus plants were reported to be grown by the 19 major nurseries that responded to the survey. About 88% of all Taxus plants reported in the survey were grown in the three-state area of Ohio, Michigan, and Pennsylvania. Taxus × media `Densiformis', `Hicksii', and `Brownii' were found to be grown by nearly all nurseries in the survey; more than half grew T. × media `Wardii' and T. cuspidata `Capitata', while other well-known cultivars seem to have been specialties of one or two nurseries. Annual clippings yields on a dry-weight basis (db) ranged from ≈20 g/plant to 140 g/plant. Expected yields were found to be very dependent upon plant age and cultivar. Taxus × media `Hicksii' appeared to be the most ideal ornamental yew that could provide a renewable source of taxol because of immediate availability and potential for mechanical harvesting of upright clippings. An estimated 3000 to 4000 ovarian cancer patients could be treated annually with the taxol currently available for extraction from T. × media `Hicksii' clippings.
Nathaniel A. Mitkowski and Arielle Chaves
that there were no substantial differences on clipping yield reduction or root depth reduction among the DMI fungicides tested under field conditions when applied to creeping bentgrass. Although no differences on rooting depth were observed in either
Nikolaos Ntoulas, Panayiotis A. Nektarios, and Glykeria Gogoula
OMC soil amendment effects on bermudagrass establishment and growth was performed through turf visual quality ratings, clipping yields, root growth, and vertical detachment force measurements. In addition, substrate properties were also evaluated and
Acidifying soil to prevent annual bluegrass (Poa annua L.) from infesting creeping bentgrass (Agrostis palustris Hud.) reduces soil P and Ca availability. This study examined Ca and P effects on the growth of these two grasses in four moderately acidic soils using CaSO4 as a Ca source. Each soil received four P rates (0, 10, 40, or 80 mg·kg-1) and three Ca (as CaSO4) rates (0, 400, or 800 mg·kg-1). Neither Ca nor P treatments substantially changed pH or exchangeable soil Al. Clipping yields, tissue P concentration, and P uptake of both grasses were affected by soil NaHCO3-P levels. Compared to bentgrass, annual bluegrass had higher clipping yields and P uptake at high P rates or high NaHCO3-P levels; this result indicates that annual bluegrass was as acid-tolerant as the bentgrass, provided that available P in the soil is adequate. Adding CaSO4 to the Papac soil, which contained the least amount of exchangeable Ca among the four soils, markedly enhanced the clipping tissue P concentration and P uptake of creeping bentgrass but not those of annual bluegrass; this result indicates that a differential response to Ca existed between the two grasses. Maintaining an adequate soil Ca availability was necessary to improve bentgrass growth, particularly for the acid soil containing low available Ca initially.
Bobby D. McCaslin, Michael R. Hughes, and Arden A. Baltensperger
A field experiment was conducted to determine if the turf quality of bermudagrass (Cynodon dactylon L. Pers.) was influenced by an interaction of genotype and nitrogen fertilization. The currently recommended level for maintenance of adequate quality in New Mexico bermudagrass turf is 48 kg N/ha per month during the growing season, the highest rate used in the study. The response of 10 bermudagrass genotypes, ‘Common’, ‘FB 49’, ‘FB 119’, ‘FB 133’, ‘N-7’, ‘NM-B1’, ‘Ormond’, ‘Santa Ana’, ‘Tifgreen’, and ‘Texturf 10’ were evaluated at N levels of 0, 16, 33 and 48 kg N/ha per month during the growing season. Color, density, and clipping yield responses of the genotypes differed for the four N fertility Ievels.‘Texturf 10’ had the highest overall ranking at 48 kg N/ha per month and ‘Ormond’ had the highest ranking at 32 and 16 kg N/ha per month. Thus, cultivar selection must be considered in arriving at precision N fertilization of bermudagrass turf.
Edward W. Bush, Wayne C. Porter, Dennis P. Shepard, and James N. McCrimmon
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).
Christian M. Baldwin, A. Douglas Brede, and Jami J. Mayer
hand-held reflectance meter (CM 1000; Spectrum Technologies, Plainfield, IL). Each individual reading measured an area ≈5.7 inches wide. Three readings were recorded for each plot and then averaged. Clipping yield (ounces per square foot) was collected