Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] is a common grass species in the eastern half of the USA, but legumes grown with it could provide benefits. Obstacles to legume establishment in fescue pastures...Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] is a common grass species in the eastern half of the USA, but legumes grown with it could provide benefits. Obstacles to legume establishment in fescue pastures include disease, insect damage, and grass competition. Experiments were performed in 2010 and 2011 at Site 1 to test the efficacy of insect control, disease control, and two methods of grass suppression on seedling establishment of three legumes. The highest seedling density of red clover (Trifolium pretense L.) was obtained with glyphosate treatment regardless of pest control and for clipping without pest control. No overall or consistent benefit was found for white clover (Trifolium pretense L.) or trefoil (Lotus corniculatus L.) from seed and foliar insecticides or fungicides, or for grass suppression by either clipping or glyphosate application. Experiments were performed in 2012 and 2013 at Site 2 to test the efficacy of grass suppression by grazing cattle or by clethodim application. Seedling density of red clover was not significantly improved by either treatment, but the density of birdsfoot trefoil was increased by clethodim, and the density of white clover was increased in 2013 by both methods of grass suppression. Overall, red clover was least sensitive to grass competition. Birdsfoot trefoil was better served by the immediate effect of chemical suppression, whereas white clover benefitted most from the lengthier grass suppression provided by grazing.展开更多
Alfalfa (Medicago sativa Leyss) is an important forage crop whose production is hampered by pests, including the alfalfa weevil (Hypera postica Gyllenhal) which is a major problem in many areas. Flaming during dormanc...Alfalfa (Medicago sativa Leyss) is an important forage crop whose production is hampered by pests, including the alfalfa weevil (Hypera postica Gyllenhal) which is a major problem in many areas. Flaming during dormancy could be an alternative control measure. Late fall and early spring flaming at three intensities were compared with pesticide and no treatment for their effects on alfalfa weevil damage and weed density. In four site-years, flaming at high intensity generally reduced weevil damage to alfalfa. When winter annual broadleaf weeds were prevalent, flaming decreased their density. When fall and spring flaming effects were different, spring flaming gave better results.展开更多
One of the inputs required by daily decision support tools for scheduling irrigation is the amount of water supplied by rainfall. In-field measurements of daily precipitation are expensive or laborious, while measurem...One of the inputs required by daily decision support tools for scheduling irrigation is the amount of water supplied by rainfall. In-field measurements of daily precipitation are expensive or laborious, while measurements from gauges within a few kilometers are frequently not representative due to the high spatiotemporal variability of precipitation. Online radarbased precipitation analyses from NOAA’s National Weather Service (NWS) have obvious potential to provide the needed data, but are known to have varying degrees of accuracy with location and conditions. The NWS precipitation analysis is computed on a 4 km × 4 km grid, so differences should also be expected between the product and individual gauge measurements under each grid cell. In order to test the utility of the NWS precipitation analysis in a daily irrigation scheduler, daily data were gathered in July 2012 from 18 weather stations under 2 NWS precapitation analysis grid cells across instru-mented research and production fields in the Mississippi Delta. Differences between individual station measurements and the NWS precipitation analysis are examined, and root-zone daily soil water deficits computed using both station data and the NWS precipitation analysis. Sub-grid spatial variability between gauge locations, and differences in precipitation between gauges and the gridded NWS analysis, are found to be similar to those reported elsewhere. Differences between time series of soil water deficit computed using the two different precipitation data sources are noted, but prove to be of limited impact on the decision to irrigate or not to irrigate. It is also noted that profile-filling rainfalls limit the impact of accumulating error, resetting the modeled soil water to “full”. Given the Delta-local practice of irrigating to replace full evapotranspirational water used, use of the NWS daily precipitation analysis data as input for a daily irrigation scheduler is judged not only acceptable, but also preferable to other sources of daily precipitation data.展开更多
文摘Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] is a common grass species in the eastern half of the USA, but legumes grown with it could provide benefits. Obstacles to legume establishment in fescue pastures include disease, insect damage, and grass competition. Experiments were performed in 2010 and 2011 at Site 1 to test the efficacy of insect control, disease control, and two methods of grass suppression on seedling establishment of three legumes. The highest seedling density of red clover (Trifolium pretense L.) was obtained with glyphosate treatment regardless of pest control and for clipping without pest control. No overall or consistent benefit was found for white clover (Trifolium pretense L.) or trefoil (Lotus corniculatus L.) from seed and foliar insecticides or fungicides, or for grass suppression by either clipping or glyphosate application. Experiments were performed in 2012 and 2013 at Site 2 to test the efficacy of grass suppression by grazing cattle or by clethodim application. Seedling density of red clover was not significantly improved by either treatment, but the density of birdsfoot trefoil was increased by clethodim, and the density of white clover was increased in 2013 by both methods of grass suppression. Overall, red clover was least sensitive to grass competition. Birdsfoot trefoil was better served by the immediate effect of chemical suppression, whereas white clover benefitted most from the lengthier grass suppression provided by grazing.
文摘Alfalfa (Medicago sativa Leyss) is an important forage crop whose production is hampered by pests, including the alfalfa weevil (Hypera postica Gyllenhal) which is a major problem in many areas. Flaming during dormancy could be an alternative control measure. Late fall and early spring flaming at three intensities were compared with pesticide and no treatment for their effects on alfalfa weevil damage and weed density. In four site-years, flaming at high intensity generally reduced weevil damage to alfalfa. When winter annual broadleaf weeds were prevalent, flaming decreased their density. When fall and spring flaming effects were different, spring flaming gave better results.
文摘One of the inputs required by daily decision support tools for scheduling irrigation is the amount of water supplied by rainfall. In-field measurements of daily precipitation are expensive or laborious, while measurements from gauges within a few kilometers are frequently not representative due to the high spatiotemporal variability of precipitation. Online radarbased precipitation analyses from NOAA’s National Weather Service (NWS) have obvious potential to provide the needed data, but are known to have varying degrees of accuracy with location and conditions. The NWS precipitation analysis is computed on a 4 km × 4 km grid, so differences should also be expected between the product and individual gauge measurements under each grid cell. In order to test the utility of the NWS precipitation analysis in a daily irrigation scheduler, daily data were gathered in July 2012 from 18 weather stations under 2 NWS precapitation analysis grid cells across instru-mented research and production fields in the Mississippi Delta. Differences between individual station measurements and the NWS precipitation analysis are examined, and root-zone daily soil water deficits computed using both station data and the NWS precipitation analysis. Sub-grid spatial variability between gauge locations, and differences in precipitation between gauges and the gridded NWS analysis, are found to be similar to those reported elsewhere. Differences between time series of soil water deficit computed using the two different precipitation data sources are noted, but prove to be of limited impact on the decision to irrigate or not to irrigate. It is also noted that profile-filling rainfalls limit the impact of accumulating error, resetting the modeled soil water to “full”. Given the Delta-local practice of irrigating to replace full evapotranspirational water used, use of the NWS daily precipitation analysis data as input for a daily irrigation scheduler is judged not only acceptable, but also preferable to other sources of daily precipitation data.
