No abstract

Cyperus esculentus is an invasive perennial sedge that can cause huge losses in arable crops. Current control strategies are based on combinations of cultural, mechanical, and chemical measures, repeated over years. Recent commercial releases of safe innovative electric weeders, offer promising alternative opportunities for controlling perennial weeds with high energy/high frequency electricity. To evaluate the effect of a single electrocution application on the efficacy of C. esculentus control, field experiments were performed in two locations in Belgium. Two electric weeding devices were evaluated: Zasso XP300, delivering a high-frequency, phased direct current (maximum voltage of 7000 V and maximum power output of 2000 W per square meter of green biomass, driving speeds between 1.1 and 3.0 km·h−1), and Rootwave Pro, delivering high-frequency alternating current (maximum voltage of 5000 V and power output between 7.5 and 10 kVA, treatment duration of 2 s). The impact of various technical (driving speed and voltage), biotic (clone and growth stage), and abiotic parameters on electrocution efficacy was evaluated. Plant responses to electrocution were evaluated by examining the vitality of treated C. esculentus mother tubers and shoots. Both devices were ineffective at mother tuber control, regardless of their burial depth (−5 cm to −15 cm), but were highly effective against aboveground shoots with reductions of vitality of up to 91% and 100% after a single pass with Zasso XP300 and Rootwave Pro, respectively. Maximum reductions were obtained when electricity was delivered at low speed (1.1 to 1.5 km·h−1) and on 5-leaf shoots without heat or water stress. Remarkably, the lowest efficacies were found on water-stressed soils at the time of application. Voltage had no effect on the degree of C. esculentus control. The efficacy of electricity was not affected by clone, irrespective of electric weeding device. Electrocution is a useful and effective control method within any integrated control strategy for controlling emerged shoots. However, as C. esculentus mother tubers are not affected by a single treatment, season-long repeated treatments are needed to exhaust the mother tubers.

Mini-plant experiments  Raw or citric acid treated (1 h at 25°C) sugarcane bagasse as feedstocks.  Continuously operated bench scale setup based on the auger reactor technology.  Non-catalytic fast pyrolysis reactor temperature: 500 °C. Schematic drawing of the mini-plant. Adapted from [7]. Bio-oils were examined by pH, solids and water content (i.e. Karl Fisher Titration), the higher heating value (HHV, using a bomb calorimeter) and GC/MS analysis.

Cyperus esculentus is considered the sixteenth worst weed in the world. The weed causes huge losses in arable crops. Current control strategies are based on combinations of chemical and mechanical methods, repeated over years, and aim to deplete the belowground bud bank. However, this is a slow process. Anaerobic soil disinfestation (ASD) using readily decomposable carbon sources may be a promising innovative method to quickly deplete the bud bank. This study investigated the effect of ASD with fresh grass clippings (dosage of 80 tonnes ha−1) differing in C:N ratio and Herbie® (consists of organic by-products from the food processing industry, dosage of 25 tonnes ha−1) on the vitality of small and large C. esculentus tubers buried at three depths (5, 15, and 30 cm) into two soils differing in soil type and soil moisture content. Their effects were compared with the effect of chemical soil disinfestation (CSD) with metam-sodium (153 kg ha−1). ASD with Herbie® showed at least equal performance compared with CSD with metam-sodium, with reductions in tuber vitality up to 97.5%. The performance of ASD with grass clippings was less consistent across soils and was affected by the C:N ratio of the grass. Both ASD and CSD showed the highest performance in moist, sandy soil and on small tubers. ASD is an effective and promising method to quickly deplete the C. esculentus bud bank, provided that the soil is sandy and moist, the carbon source has a C:N ratio of about 10, and the incorporation depth is at least 25 cm. To foster the implementation of ASD, future research should evaluate its performance consistency across environments and years.