Rhizome Fragmentation by Vertical Disks Reduces Elymus repens Growth and Benefits Italian Ryegrass-White Clover Crops

Abstract

Tillage controls perennial weeds, such as Elymus repens, partly because it fragments their underground storage organs. However, tillage is difficult to combine with a growing crop, which limits its application. The aim of this study was to evaluate how soil vertical cutting with minimum soil disturbance and mowing affect the growth and competitive ability of E. repens in a grass–clover crop. A tractor-drawn prototype with vertical disks was used to fragment E. repens rhizomes with minimal soil and crop disturbance. In experiments performed in 2014 and 2015 at a field site close to Uppsala, Sweden, the rhizomes were fragmented before crop sowing (ERF), during crop growth (LRF), or both (ERF+LRF). Fragmentation was combined with repeated mowing (yes/no) and four companion crop treatments (none, Italian ryegrass, white clover, and grass/clover mixture). The results showed that in the grass–clover crop, rhizome fragmentation reduced E. repens rhizome biomass production and increased Italian ryegrass shoot biomass. ERF and LRF both reduced E. repens rhizome biomass by about 38% compared with the control, while ERF+LRF reduced it by 63%. Italian ryegrass shoot biomass was increased by 78% by ERF, 170% by LRF and 200% by ERF+LRF. Repeated mowing throughout the experiment reduced E. repens rhizome biomass by about 75%. Combining repeated mowing with rhizome fragmentation did not significantly increase the control effect compared to mowing alone. We concluded that rhizome fragmentation using vertical disks can be used both before sowing and during crop growth to enhance the controlling effect of grass–clover crops on E. repens.

Interactive Effects of Subsidiary Crops and Weed Pressure in the Transition Period to Non-Inversion Tillage, A Case Study of Six Sites Across Northern and Central Europe

“…However, the use of mixtures of legumes with grass or Brassicaceae species often had an advantage over pure stands of the same legume species, similarly to Baraibar et al [54]. Mixtures can occupy more ecological niches than pure stands and combine different modes of competition, for example by evenly reducing both below and aboveground weed biomass instead of primarily reducing just one [61,63]. In case of the failure of one species component, the other species can compensate [64].…”

A Review of Non-Chemical Management of Couch Grass (Elymus repens)

“…However, competitive ability varies considerably among different crops and crop varieties. Ringselle et al, [22,83] found that ryegrass was more effective at reducing E. repens shoot biomass, while red clover was more effective at reducing rhizome biomass. Cussans [24,84] found that barley and oilseed rape are more competitive against E. repens than wheat and field beans, and similar rankings have been made by others (e.g., [79,[85][86][87]).…”

“…Comparatively, Courtney [114] found that a four-week mowing interval was sufficient to prevent rhizome production; Štýbnarová et al [108] found that three harvests per year kept E. repens below 10-15% of the grassland coverage; and Pavlu et al [115] found E. repens populations gradually decreasing already at two grassland harvests per year. Moreover, more recent studies in Sweden found that when cut every time it reached two leaves during summer, E. repens rhizome biomass was reduced by >75% compared to no mowing [83,116]. However, there appears to be some influence of season on mowing efficacy, as mowing post-cereal harvest has had a limited effect on E. repens, at least in the Nordic countries [102,103,116].…”

“…Ringselle et al [83] and Ringselle et al (Unpublished) tested a prototype from Kverneland with vertical coulter disks that cut through the soil and rhizomes with minimal soil disturbance. Both sets of experiments tested the prototype in spring and/or in summer in a grass and/or clover crop and aimed to use the same 10 × 10 cm grid as in Bergkvist et al [116].…”

Influence of mechanical weeding and fertilisation on perennial weeds, fungal diseases, soil structure and crop yield in organic spring cereals

“…This may have several environmental benefits, but lack of weed control of this strategy postharvest (in autumn) was recently shown by Bergkvist et al (2017). However, Ringselle et al (2018), using the same vertical cutter for control of E. repens when renewing a ley, concluded that rhizome fragmentation by this tool reduced growth of E. repens and benefited ryegrass and white clover crops.…”