An Evaluation of Herbicides for Control of Wild Oats in Barley: Efficacy, Phytotoxicity, and Barley Variety Susceptibility Studies

The control of wild oats (Avena Jatua L.) in Alaskan spring-planted barley was investigated in a series of experiments conducted from 1981-1984. Rates and times of applications of triallate (a preemergence, soil-incorporated herbicide), diclofop, barban, and difenzoquat (postemergence herbicides) were investigated in relation to control of wild oats and barley yield in 1981-1982. Because of very high wild oats populations. none of the herbicides controlled wild oats to the point of· allowing a barley harvest. Generally, wild oats were best controlled when herbicides were applied at an early growth stage and at the highest application rates. Control of wild oats with triallate was the same whether incorporated using parallel or perpendicular passes of a spike-tooth harrow. In 1983-84 both single herbicide treatments and combinations of herbicides were studied. Barban, diclofop, and difenzoquat were applied alone or with triallate applied in the fall or spring in emulsifiable concentrate or granular formulation. Wild oats population levels were lower in these 2 years, and applications of even single herbicides provided good wild oats control. Of the individual herbicides, diclofop provided the best control of wild oats. In general, when triallate was applied in conjunction with diclofop, barban, or difenzoquat, control of wild oats was better and higher barley yields were obtained than when a single wild oats herbicide was applied. When triallate was applied in the fall, the granular formulation provided better control of wild oats than the emulsifiable formulation. In a study of the response of eight barley varieties ('Eero', 'Paavo', 'Galt', 'Otra', 'Otal', 'Datal', 'Udal', 'Weal') to high rates and late times of application of the four herbicides, none of the varieties were differentially susceptible. Diclofop decreased heights of all varieties and decreased test weights

Weed Control in Annual Strawberries Grown with Plastic Mulch: Efficacy, Phytotoxicity, and Soil Persistence Studies

Cool soil temperatures in Alaska are a limiting factor for many crops. Clear plastic mulch has been shown to increase soil temperatures, and use of this mulch has allowed the production of many warm season crops farther north than they could otherwise be grown. Clear plastic mulch and row covers are used in interior Alaska to promote early growth and increase yields of strawberries

Shifting feelings

Sarah Conn explores the complex feelings that accompany being an international student in the UK

A phenomenological study of help seeking behaviours and coping strategies of international students of non-European backgrounds

The aim of this study is to explore the subjective experience of what are the help-seeking behaviours and coping strategies of international students from non-European backgrounds. Eighteen students from eleven non-European countries on three sites were interviewed. Using a phenomenological approach, the study seeks to capture the knowledge of the experiential experts, i.e., the students themselves, with the hope that it can be used to enhance provision for this client group in university counselling services. The study was motivated by the distinct under-use and under-representation of such students using traditional counselling services. Interpretative Phenomenological Analysis (IPA) was employed to address the research questions from a first-person-perspective, helping to shed light on the sense making of international Students of non-European backgrounds, when confronted with challenge. Themes such as culture shock, culture, family, spirituality/religion, identity, sense of justice, resistance, perceived barriers and reflections on how to improve transition were categorised, with impact of transition, living with challenge – coping, living with challenge – seeking help; shifting identities and enhancing cultural engagement as superordinate themes emerging. The study revealed that patterns of help-seeking typically followed preferential relationships, called here hierarchy of helping. The findings are discussed with regard to implications for individual practice and staff training in transcultural work to enhance cultural engagement in educational settings

An Evaluation of Herbicides for Broadleaf-Weed Control in Rapeseed: Efficacy, Phytotoxicity, and Soil Persistence Studies

At the recommended rates (1.0 lb/A for trifluralin, ethalfluralin, EL5261; 0.75 lb/A for dinitramine; 1.2 lb/A for nitrofen), none of the herbicides we evaluated in these studies reduced rapeseed stands, yields, or test weights. However, at higher rates (1. 5, 3.0 lb A), dinitramine reduced rapeseed stands, but this did not result in decreased yields. None of the other herbicides reduced rapeseed stand, yield, or test weights when applied at up to four times the recommended rate. No trifluralin residues were detected in rapeseed whole-plant or seed samples. All of the herbicides provided adequate control of common lambsquarters (Chenopodium album L.). Corn spurry (Spergula arvensis L.) was controlled by trifluralin. ethalfluralin. EL-5261, and nitrofen. All of the herbicides except nitrofen controlled chickweed [Stellaria media (L.) Cyrillo]. In 1979, 51 per cent of the trifluralin applied remained at the end of the growing season in one study while 26 per cent remained in another study. The rate of degradation at three sites in 1979 were as follows (greatest to least); Delta Junction, Matanuska Valley, Fairbanks. Degradation rates of trifluralin were not significantly different in three soil types or at two different application rates. Trifluralin showed no signs of leaching through the soil profile. In 1981, 25 per cent of the trifluralin, 8 per cent of the ethalfluralin, and 24 per cent of the EL-5261 applied remained at the end of the growing season. Despite the relatively long persistence of these preplant, incorporated herbicides, yields and test weights of barley planted in succeeding years were not reduced. A benefit of these persistent residues was control of broadleaf weeds in the succeeding barley crop

Postemergence Broadleaf Weed Control in Barley

Experiments were conducted from 1981-1983 to determine the efficacy and phytotoxicity of postemergence herbicides used to control broadleaf weeds in spring-planted barley. The following herbicides were evaluated: MCPA amine (0.37, 0.75, 1.5 lb/A, active ingredient), 2,4-D amine (0.25, 0.5, 1 lb/A), bromoxynil (0.21, 0.43, 0.86 lb/A), and metribuzin (0.11, 0.21, 0.43, 0.86 lb/A). In 1982 and 1983, three additional herbicides were included: dinoseb (0.25, 0.5, 1 Ib/A), dicamba (0.09, 0.18, 0.36 lb/A), and chlorsulfuron (0.04, 0.07, 0.14 lb/A). Weed control was determined through measurements of weed biomass in each herbicide and control plot. Phytotoxicity was measured by barley yield and test weight in all years, and additionally by germination of seed produced in 1982. None of the herbicides except dicamba in 1982 significantly reduced the yield or test weights of barley below that of the control. Common lambsquarters was the only weed present in 1981 and 1982. Bromoxynil and metribuzin provided both early-and late-season control MCPA, 2,4-D, and j dinoseb took longer to control common lambsquarters but provided adequate control by midseason. Dicamba did not control common lambsquarters as well as the other herbicides. In 1983, prostrate knotweed was also present at the study site. None of the herbicides significantly reduced the number of prostrate knotweed below that of the control Germination of 'Galt' barley was not \, affected by treating parent plants with any of the herbicides tested. The following barley varieties were screened for susceptibility to metribuzin injury in 1982: Galt, Lidal, Weal, Otal, Datal, Eero, Paavo, Otra, and Klondike. Only 'Klondike' was highly sensitive to metribuzin

Hybrid force and position control of a manipulator with an elastic link

This thesis describes the hybrid force and position control of an elastic manipulator constrained by a surface. Based on the inverse and predictive control techniques, the proposed controller minimizes a quadratic function of contact force error, tip tracking error, elastic deflection, and control torques. Applying the proposed controller to a two-link planar manipulator where the first link is rigid and the second elastic, computer simulation and laboratory experiment results are presented to show the effectiveness of the proposed controller for force and position control and elastic mode stabilization

An assessment of the impact of water impoundment and diversion structures on vegetation in Southern Arizona

High-altitude color infrared photography was used to survey existing conditions, both upstream and downstream, from nineteen diversion structures in Southern Arizona to determine their effect upon vegetation health, vigor, and cover. A diversion structure is defined as a man/made feature constructed to control storm runoff. The results are used to determine the policy for future structure design