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

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

Toward an internally consistent astronomical distance scale

Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been established. We review current efforts to homogenize the Local Group's distance framework, with particular emphasis on the potential of RR Lyrae stars as distance indicators, and attempt to extend this in an internally consistent manner to cosmological distances. Calibration based on Type Ia supernovae and distance determinations based on gravitational lensing represent particularly promising approaches. We provide a positive outlook to improvements to the status quo expected from future surveys, missions, and facilities. Astronomical distance determination has clearly reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press (chapter 8 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age