Contrasting cover-cropping systems were compared to determine whether fundamental differences in cover-cropping strategies affect weed seed predators and resulting seed predation. We conducted typical “feeding” trials in which 25 seeds of each of six weed species, including velvetleaf, wild mustard, yellow foxtail, common lambsquarters, redroot pigweed, and hairy galinsoga, were placed in the field. Exclosures showed that the majority of seed predation could be attributed to invertebrates: 43% out of a total of 56% seed predation for 11 d in 2002 and 40% out of a total of 58% seed predation for 4 d in 2003. The predominant invertebrate seed predator across all entry points of four cropping systems was a ground-dwelling carabid beetle, Harpalus rufipes, which was more abundant in vegetated treatments, particularly red clover, compared with treatments recently tilled and planted to a fall cover crop. In the absence of vertebrates, H. rufipes activity–density was positively correlated with mean seed predation in 2002 (Spearman ρ = 0.489; P < 0.001) but not in 2003 (Spearman ρ = 0.090; P = 0.504), possibly because of a delay between pitfall trapping and predation assay. The activity–density of invertebrate seed predators measured in these systems and the high level of predation imposed on weed seeds at the soil surface indicate that cover-cropping strategies should consider late-season weed management, which maintains seeds on the soil surface and provides desirable habitat for invertebrate predators.
Few options exist for effectively managing weeds in organic spring cereals. Establishing a competitive crop through increased seeding rate provides improved weed suppression, but competition with inter-row weeds is delayed, compared with an alternative, more uniform spatial pattern of sowing. We speculated that (i) enhanced interspecific competition or (ii) improved physical weed control with a strategy of wide-row sowing and inter-row hoeing would both provide better weed control than current regional organic practices. However, whether one of these strategies is superior to the other depends on an economic analysis of the relative costs of seed and equipment. We tested this hypothesis in two field experiments with spring barley (Hordeum vulgare) at three row spacings (11.4, 17.7 and 22.8 cm), and by sowing in a more uniform pattern, using condiment mustard (Sinapis alba) as a surrogate weed. Standard regional organic practice (17.7 cm rows, 200 plants m )2 ) had the highest weed biomass at the conclusion of both seasons. Weeds in this treatment accounted for 57% of total above-ground plant biomass in 2007 and 27% in 2008. The more uniform sowing pattern reduced weed biomass by 26% compared with the regional standard, averaged over 2 years of the experiment. Although we expected enhancing crop competition to be the most economical practice, high cost of organic seed resulted in intermediate net returns. At high weed density, the wide row strategy offered improved weed control, yields and profitability. However, with lower weed density, spring barley was sufficiently competitive that it did not benefit from cultivation.-2008 Minnesota machinery total cost per ha for a high-residue cultivator with guidance system.Managing weeds in organic spring cereals 603
Weeds remain the foremost production challenge for organic small grain farmers in the northeastern United States. Instead of crops sown in narrow, single-line rows, band sowing offers a more uniform spatial arrangement of the crop, maximizing interspecific while reducing intraspecific competition. Weeds in the inter-band zone are controlled by cultivating with aggressive sweeps; tine harrowing can target weeds in both intra- and inter-band zones. Field experiments in Maine and Vermont in 2016 and 2017 evaluated band sowing for improved weed control, crop yield, and grain quality in organic spring barley (Hordeum vulgare L. ‘Newdale’). Specifically, we compared: (1) the standard practice of sowing 16.5-cm rows at a target crop density of 325 plants m−2, (2) narrow-row sowing with increased crop density, (3) wide-row sowing with interrow hoeing, and (4) band sowing both with and (5) without inter-band hoeing. Mustard (Sinapis alba L. ‘Ida Gold’) was planted throughout the experiment as a surrogate weed. Compared with the standard practice, band sowing with hoeing reduced surrogate weed density on average by 45% across site-years. However, effects on weed biomass and yield were inconsistent, perhaps due to suboptimal timing of hoeing and adverse weather conditions. In 1 out of 4 site-years, band sowing with hoeing reduced surrogate weed biomass by 67% and increased crop yield compared with the standard treatment. Results also indicate that band sowing with hoeing may improve 1,000-kernel weight and plump kernel grain-quality parameters.
Percutaneous vertebroplasty (PVP) is an increasingly common intervention, and complications resulting from embolization are increasingly observed. We report a case of polymethyl methacrylate (PMMA) embolization resulting in cardiac complications in a frail patient, which was managed with endoscopic robotic-assisted removal of the embolized material.
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