The effects of fall applications of glyphosate on johnsongrass, soy beans, and corn

Controlling johnsongrass [Sorghum halepense (L). Pers.] in such agronomic crops as corn (Zea mays L.) and soybeans [Glycine max (L.) Merr.] presents a major problem to many farmers. Although several preemergence herbicides have been developed to control seedling johnsongrass, in general rhizome johnsongrass is primarily responsive only to foliar-applied chemicals. One such postemergence chemical which gives excellent control of rhizome johnsongrass is glyphosate (N-phosphonomethyl glycine). If glyphosate is applied in the spring, a waiting period is required both before spraying to allow johnsongrass foliage to develop and then for trans location of the herbicide following application. As this waiting period may cause an undesirable delay in planting date, a fall application would be more favorable. The objectives of this study were (1) to determine the effectiveness of fall applications of glyphosate for controlling rhizome johnsongrass, (2) to determine the response of corn and soybeans to glyphosate applications made immediately prior to crop maturity, at maturity, and following maturity. A field experiment was conducted at Ames Plantation, Grand Junction, Tennessee, and at the Knoxville Plant Science Field Laboratory, Knoxville, Tennessee. The corn treatments were applied at various grain moisture levels beginning at about 45 percent and continuing through 15 percent. Soybean treatments were applied at one week intervals beginning at three weeks prior to crop maturity and continuing through two weeks past maturity. Johnsongrass treatments corresponded to soybean treatments, except for one early fall treatment applied on August 29. Due to calibration error, the rates of glyphosate application varied between locations. The resulting rates were 1.68 kg/ha at Ames Plantation and 2.24 kg/ha at Knoxville. The glyphosate application made at Knoxville on corn at the 47 percent grain moisture level caused a significant reduction in seed moisture and weight at harvest. However, when the corn was treated at grain moisture levels of 40 to 15 percent, the glyphosate had no effect on lodging, yield, seed moisture, or seed weight at either location. Corn progeny germination was not affected by any of the glyphosate applications. Nevertheless, treatments at grain moisture levels of 35 percent and higher caused serious reductions in progeny seedling emergence, vigor, and weight at 21 days. The emergence of abnormal progeny seedlings was also increased by these same treatments. In addition, there tended to be a reduction in primary root length of these injured seedlings. The glyphosate application made three weeks prior to soybean maturity at Ames reduced seed weight. This treatment also produced drastic reductions in progeny seedling emergence, vigor, weight at 21 days, and primary root length. Furthermore, this treatment increased dry matter content of the seedlings. The subsequent treatments at Ames, as well as all the treatments at Knoxville were applied after the onset of soybean senescence. Consequently, these treatments caused no effect whatsoever on the treated soybeans or their progeny. Protein and oil content of the corn and soybean seed from treated plants was not affected by any of the fall applications of glyphosate. The earliest glyphosate treatments produced the best control of rhizome johnsongrass. Applications made between August 29 and October 18 resulted in 80-95 percent rhizome control. Treatments made on October 24 and 31 gave only fair rhizome control, while no control resulted from a November 7 application. From these data, the optimum treatment stage for controlling johnsongrass in corn or soybeans would appear to be (1) when the corn grain moisture level is below 35 percent, (2) after the onset of soybean senescence, and (3) prior to mid October if johnsongrass is to be controlled in either crop

Rotationally actuated prosthetic helping hand

A prosthetic device has been developed for below-the-elbow amputees. The device consists of a cuff, a stem, a housing, two hook-like fingers, an elastic band for holding the fingers together, and a brace. The fingers are pivotally mounted on a housing that is secured to the amputee's upper arm with the brace. The stem, which also contains a cam, is rotationally mounted within the housing and is secured to the cuff, which fits over the amputee's stump. By rotating the cammed stem between the fingers with the lower arm, the amputee can open and close the fingers

Geochemical variations in an alpine lake and watershed underlain by siliciclastic bedrock, Uinta Mountains, Utah

Journal ArticleA small watershed which includes several small lakes in the Uinta Mountains of northern Utah is underlain by monolithologic Precambrian siliciclastic rock with extremely limited buffering capacity. In spite of this, s\ stematic spatial and temporal variations in alkalinity, pH, and major elements occur in springs, small streams, and one lake within the watershed. Alkalinity changes by 3-fold over 1 km of vertical elevation within the watershed. Cations and silica show similar although less dramatic changes with respect to elevation. Silicate weathering seems to constitute the dominant mechanism of alkalinity generation. The water column in Marshall Lake shows significant seasonal stratification of temperature and chemical constituents. Vertical variation of alkalinity in the lake during the summer is related to the input of geochemically distinct water sources in the watershed. Vertical pH variations in Marshall Lake do not match alkalinity variations but instead are related to photosynthesis in the upper and middle portions of the water column. Thermal and chemical stratification is greater in the lake than in well-studied alpine lakes of the Sierra Nevada. Numerical hydrodynamic models suggest that temperature and chemical stratification of this Uinta Mountain lake can be attributed to lake depth (13 m vs more shallow depths of the Sierra lakes) or relatively weak wind shear stress. The combined watershed/lake study demonstrates the need for complete vertical water sampling in order to accurately characterize the geochemistry of deep (> 10 m) alpine lakes

The Impact of Information Literacy-Related Instruction in the Science Classroom: Clickers Versus Nonclickers

The goal of information literacy instruction is to enable students to develop skills that they can use for life to facilitate their empowerment through information. Instruction librarians, particularly those teaching Millenials whose need for “hands on” instruction has been widely emphasized, are constantly searching for methodologies that will provide appropriate levels of interactive instruction. Many methods for enhancing the relevance of library instruction have been discussed in the literature. This study, designed and developed by a collaborative team of librarians and science faculty, describes the effects of providing course-integrated, interactive (with clickers) information literacy instruction to undergraduates at a small private nonprofit university in the Southeast

Drinking-Water Arsenic Exposure Modulates Gene Expression in Human Lymphocytes from a U.S. Population

BACKGROUND: Arsenic exposure impairs development and can lead to cancer, cardiovascular disease, and diabetes. The mechanism underlying these effects remains unknown. Primarily because of geologic sources of contamination, drinking-water arsenic levels are above the current recommended maximum contaminant level of 10 µg/L in the northeastern, western, and north central regions of the United States. OBJECTIVES: We investigated the effects of arsenic exposure, defined by internal biomarkers at levels relevant to the United States and similarly exposed populations, on gene expression. METHODS: We conducted separate Affymetrix microarray-based genomewide analyses of expression patterns. Peripheral blood lymphocyte samples from 21 controls interviewed (1999–2002) as part of a case–control study in New Hampshire were selected based on high- versus low-level arsenic exposure levels. RESULTS: The biologic functions of the transcripts that showed statistically significant abundance differences between high- and low-arsenic exposure groups included an overrepresentation of genes involved in defense response, immune function, cell growth, apoptosis, regulation of cell cycle, T-cell receptor signaling pathway, and diabetes. Notably, the high-arsenic exposure group exhibited higher levels of several killer cell immunoglobulin-like receptors that inhibit natural killer cell activity. CONCLUSIONS: These findings define biologic changes that occur with chronic arsenic exposure in humans and provide leads and potential targets for understanding and monitoring the pathogenesis of arsenic-induced diseases. KEY WORDS: arsenic, drinking water, immune response, lymphocytes, microarray, U.S. population. Environ Health Perspect 116:524–531 (2008). doi:10.1289/ehp.10861 available vi

Investigation of radioactivity-induced backgrounds in EXO-200

The search for neutrinoless double-beta decay (0{\nu}{\beta}{\beta}) requires extremely low background and a good understanding of their sources and their influence on the rate in the region of parameter space relevant to the 0{\nu}{\beta}{\beta} signal. We report on studies of various {\beta}- and {\gamma}-backgrounds in the liquid- xenon-based EXO-200 0{\nu}{\beta}{\beta} experiment. With this work we try to better understand the location and strength of specific background sources and compare the conclusions to radioassay results taken before and during detector construction. Finally, we discuss the implications of these studies for EXO-200 as well as for the next-generation, tonne-scale nEXO detector.Comment: 9 pages, 7 figures, 3 table