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In a field experiment, clinoptilolitic zeolite was compared to sphagnum peat and sawdust as sand amendments at 5%, 10%, and 209” (v/v) to enhance `Penncross' creeping bentgrass (Agrostis palustris Huds.) establishment and to compare their gravimetric and volumetric cation exchange capacities and their effects on moisture retention and cation exchange capacities of the resultant mixes. In addition, cation exchange capacities and exchangeable K+ and
Although the effect of cold winters on the severity of bermudagrass (Cynodon dactylon Pers.) spring dead spot (SDS) has been studied, information is needed concerning the effect of infection by fungi associated with SDS on the host's freezing resistance. A-22 bermudagrass was inoculated with Leptosphaeria korrae J. Walker & A.M. Smith and Ophiospharella herpotricha (Fr.) J. Walker & A.M Smith. Differential thermal analysis was used to monitor exotherm temperatures of healthy and O. herpotricha- and L. korrae-infected A-22 bermudagrass at 10-day intervals during 90 days of acclimation in cold chambers. Healthy bermudagrass crowns supercooled to an average of -6.7C and fungi-infected crowns supercooled to an average of -4.8 and -4.4C, respectively. Healthy crown exotherm temperatures were significantly lower than those of fungi-infected bermudagrass crowns on all nine sampling dates. This result indicates that fungi-infected plants are more susceptible to cold damage.
Throughout the north-south climatic transition zone of the eastern United States, cool- and warm-season turfgrasses are used adjacently. A greenhouse study with creeping bentgrass (Agrostis palustris Huds.) was initiated to determine threshold concentrations of atrazine, an effective pre- and postemergence herbicide for warm-season turfgrasses, that would result in unacceptable levels of phytotoxicity to seedling and mature creeping bentgrass. Mature and 8-week-old seedling `Penncross' creeping bentgrass were given 6.5 mm of daily irrigation of untreated water or water containing atrazine at 0.01, 0.02, 0.04, 0.08, 0.16, 0.32, 0.64, 1.28, or 2.56 mg·liter-1. A model of quality ratings taken 20 days after the initiation of treatments indicated threshold concentrations resulting in unacceptable turf quality to be approximately 0.05 and 0.08 mg·liter-1 for seedling and mature bentgrass, respectively. Chemical name used: 2-chloro-4-ethylamino-5-isopropylamino-s-triazine (atrazine).
Abstract
Superimposed Amplified Exotherm Differential Thermal Analysis System is presented as a system used for detecting low-temperature exotherms of excised dormant flower buds. This system uses thermistors that do not penetrate the tissue and a liquid freezing medium for more uniform temperatures between the sample and reference. A test chamber is presented that can be used with a nonprogrammable freezer. Tests with Forsythia flower buds indicate 2 exotherms, the second of which is associated with a dramatic loss of tissue viability.
The objectives of this study were to determine the effects of high P applications on `Baron', Kentucky bluegrass (Poa pratensis L.) turf quality, chlorophyll content, soil test levels of P and K, and foliar nutrient concentration. In this 5-year field study, P was applied at 0, 22, 43, 86, 172, or 258 kg·ha-1·year-1 using triple superphosphate (210 g P/kg) in single-applications in May. Phosphorus applications did not affect overall yearly quality, chlorophyll content, or soil pH, but increased available soil P and reduced available soil K and Cu concentration in clippings.