Occurrence of Weeds in an Orchard due to Cultivation of Long-Term Perennial Living Mulches

Abstract

The living mulch permanence along with the succession of their weed infestation in an apple orchard were evaluated at the Research Station, Wrocław University of Environmental and Life Sciences. The perennial cover crops: white clover and colonial bent grass, as well as the annual dwarf nasturtium, were sown as living mulches in apple tree rows, in the year of establishing the orchard. Blue fescue was sown one year later to replace the dwarf nasturtium. The percent of covers and temporal dominance dynamics of weeds were estimated during the first 13 years of the orchard maintenance. The occurrence of annual weeds, which had been abundant in all the living mulches in the year of their sowing, decreased in the following years of orchard maintenance. Conversely, the dominance of several perennial weed species increased as the orchard reached the full cropping period. White clover exhibited the lowest permanence. Dynamic spreading of <em>Elymus repens </em>(L.) Gould and other species from the Poaceae family was the direct cause of this cover crop disappearance. The presence of perennial dicotyledonous weeds, primarily <em>Taraxacum officinale </em>Web. and <em>Convolvulus arvensis </em>L., also contributed to the diminished sod of all the living mulches. Blue fescue maintained satisfactory dominance relative to colonial bent grass for nearly the entire first decade of the research. Nevertheless, both grass living mulches were present on less than half of the tree row soil surface area, in the thirteenth year after planting of the apple trees.