Search Results (5)

Weed control in organic spinach for the processing market is challenging because of the low tolerance of weed contamination in the harvested produce and the limited physical weeding options. Optimisation of weed control systems is therefore urgently needed. Three field experiments with autumn spinach were carried out in organic fields to evaluate the impact of cultivar choice, seeding rate (300 and 400 seeds m⁻²), plant spacing management (10.5-cm-wide single rows and 21-cm-wide single or twin rows) and integrated weed management strategy (combinations of pre-sowing, pre-emergence and post-emergence tactics) on weed biomass and spinach yield and quality. Spinach cultivars with a planophile growth habit and a high growth rate were more weed suppressive than the cultivar with an erectophile growth habit and a slower growth rate. Spinach density was significantly negatively correlated with weed biomass and weed biomass fraction in the harvested produce, but significantly positively correlated with (marketable) spinach biomass and petiole fraction in the harvested produce. Narrow row spacing systems with post-emergence broadcast harrowing had the lowest weed biomass and weed biomass fraction but also the lowest (marketable) spinach biomass as a result of the thinning action of harrowing. Post-emergence harrowing is of key importance for reducing weed biomass in any integrated weed control strategy. Weediness was lowest in systems comprising flaming on false seedbed or in pre-emergence followed by post-emergence harrowing. To mitigate the risk of crop failure, the field should preferably be cropped with quickly growing spinach plants arranged in narrow spaced rows at high plant density and weeded by pre-sowing or pre-emergence flaming followed by post-emergence harrowing. Full article

The demand for pesticide-free food has increased the need for sustainable organic farming. Onion (Allium cepa L.) is an important vegetable crop cultivated worldwide. The available weed control tools for intra-row weeds following onion emergence are limited. This study aimed to evaluate the potential use of liquefied petroleum gas (LPG) flaming as a pre- and post-emergence weed control method for both direct-seeded onion seedlings and transplanted onion bulbs. The safety of cross-row, where the flames are targeted to the intra-row area from both sides of the row, and broadcast flaming for bulb onion was compared. Cross-row flaming at twelve days after planting had no effect on onion dry weight, while broadcast flaming-treated plants’ dry weight was reduced by 36% as compared to controls. For the cross-row technique, the tested burners’ angle (45° and 30°) and inter-burner distances (30 and 40 cm) had no impact on weed control efficacy, and similar control levels, between 55% (15 cm) and 45% (10 cm), were observed 15 cm from both sides of the row-center. Direct-seeded onion cultivars were treated at various growth stages. The pre-crop-emergence stage was completely safe for the crop, and the second leaf stage exhibited a wide range of tolerance levels to flaming treatment across the different onion cultivars, with dry weights ranging between 39 and 117% compared to non-treated control in the flaming sensitive and tolerant cultivars, respectively. These results were validated under field conditions using the two most tolerant cultivars (Orlando and Browny); no yield reductions were observed for either cultivar when treated from the third leaf stage. In bulb onion, flaming had no impact on dry weight of shoots or roots when applied from four weeks after planting. This study demonstrates, for the first time, the potential of using flaming as a post-emergence weed control tool for direct-seeded and bulb onion, and at earlier time points than previously shown. Cross-row flaming proved effective for controlling intra-row weeds and can lower weeding costs. Future research should evaluate the safety of sequential applications and test complementary control methods for the initial growth stages. Full article

With organic farming hectarage and cover crop interest increasing throughout the United States, effectively timed cover crop termination practices are needed that can be utilized in organic conservation tillage production systems. Four commercially available termination treatments approved by Organic Materials Review Institute (OMRI) were evaluated, immediately following mechanical termination with a cover crop roller/crimper and compared to a synthetic herbicide termination to access termination rates. Treatments included rolling/crimping followed by (1) 20% vinegar solution (28 L a.i. ha⁻¹ acetic acid), (2) 2.5 L a.i. ha⁻¹ 45% cinnamon (Cinnamomum verum L.) oil (cinnamaldehyde, eugenol, eugenol acetate)/45% clove oil (eugenol, acetyl eugenol, caryophyllene) mixture, (3) 0.15 mm clear polyethylene sheeting applied with edges manually tucked into the soil for 28 days over the entire plot area (clear plastic), (4) broadcast flame emitting 1100 °C applied at 1.2 k/h (flame), (5) glyphosate applied at 1.12 kg a.i. ha⁻¹ (this non-OMRI-approved, non-organic conservation tillage cover crop termination standard practice was included to help ascertain desiccation, regrowth, and economics), and (6) a non-treated control. Five cover crop species were evaluated: (1) hairy vetch (Vicia villosa Roth), (2) crimson clover (Trifolium incarnatum L.), (3) cereal rye (Secale cereale L.), (4) Austrian winter pea (Pisum sativum L.), and (5) rape (Brassica napus L.). Three termination timings occurred at four-week intervals beginning mid-March each year. In April or May, organic producers are most likely to be successful using a roller crimper as either a broadcast flamer for terminating all winter covers evaluated, or utilizing clear plastic for hairy vetch, winter peas, and cereal rye. Ineffectiveness and regrowth concerns following cover crop termination in March are substantial. Commercially available vinegar and cinnamon/clove oil solutions provided little predictable termination, and producers attempting to use these OMRI-approved products will likely resort to cover crop incorporation, or mowing, to terminate covers if no other practice is readily available. Full article

In this paper, we investigate the mysterious tsunami fires that occurred at Aonae Harbor on Okushiri Island during the 1993 Hokkaido Nansei-Oki earthquake. Specifically, five fishing boats moored separately from each other in the harbor suddenly caught fire and burned nearly simultaneously with the arrival of the first tsunami wave. However, the ignition mechanism of those fires has, until now, remained largely unknown. At the time the earthquake occurred, an NHK (Japan Broadcasting Corporation, Tokyo, Japan) crew that was on the island to report on its scenic natural attractions just happened to capture video footage of those tsunami-related fires. Using that NHK video footage in combination with eyewitness accounts, this study investigates the spatio-temporal process leading to those tsunami-related fires. For example, one witness said, "There was whitish bubbling in the offshore area and I saw five burning fishing boats moored on the seawall being blown about by the strong winds. The burning boats were swept ashore with the tsunami and ignited the gasoline of a car that was rolling in the waves. The fire eventually spread to the center of the Aonae District." The NHK video footage confirmed flames arising from the five fishing boats almost simultaneously and the shimmering white color of the tsunami waters striking the seawall, which were consistent with the eyewitness testimony. Based on these spatio-temporal data, we propose the following hypothetical model for the origin of tsunami fires. Combustible methane gas released from the seabed by the earthquake rose toward the surface, where it became diffused into the seawater and took the form of whitish bubbles. The tsunami strike on the Aonae Harbor seawall resulted in the generation of large electrical potential differences within the seawater mist, which quickly developed sufficient electrical energy to ignite the methane electrostatically. The burning methane bubbles accumulated on the boat decks, which then burned violently. Full article

In recent decades, anthropogenic activity and climate changes have reshaped global weed dispersal and establishment in new territories. This study aimed to evaluate the effectiveness of propane flaming approach in the control of perennial invasive and native Mediterranean broadleaf and grass weeds. The invasive weeds, Cyperus rotundus, Sorghum halepense, and Ecballium elaterium, were treated multiple times with a single propane dose (2.5 kg propane km⁻¹), using the broadcast technique. The local annual weeds, Sinapis arvensis, Lavatera trimestris, and Avena sativa, were treated once at five propane doses (0–2.5 kg propane km⁻¹), using the cross-row technique. Dose-response analysis was performed. Three applications provided effective control (up to >90%) for all tested perennials, and affected seed and flower production in Sorghum halepense and Ecballium elaterium, respectively. However, the timing of the sequential application had a significant impact on the degree of control, in terms of dry weight reduction and seed production. Weed density had an impact on control efficacy but was only a significant determinant for Ecballium elaterium. Cross-row application was effective during early growth stages of broadleaf weeds (ED₅₀ < 1.2 kg propane km⁻¹), but was less effective during later growth stages (ED₅₀ > 2.6 kg propane km⁻¹). For grass weeds, both early and late application were ineffective (ED₅₀ > 4.1 kg propane km⁻¹). More research is needed to optimize this weed control tactic for various cropping systems and weed species. Implementation of this novel approach into integrated weed management programs will increase the control efficacy of invasive weed under the projected climate changes and reduce the evolution of herbicide-resistant weeds. Full article