Research summary: About two square meters of weed-free space are required for optimal growth and production of a dwarf tree in modern, short-statured, apple orchards. Weed-free space is needed to eliminate weed interference with the tree, as well as to reduce habitat for tree-damaging rodents and other unwanted visitors. A wide variety of toxic synthetic herbicides are labelled for use in apple orchards to create the desired weed-free zones amongst apples trees, however, environmental and health aware growers prefer to eliminate herbicide use in favour of non-chemical weed control tactics. Abrasive corn cob grit applied under high air pressure was tested for the control of weeds in an established apple orchard over two years. Additionally, efficacy of abrasive grit-weeding was compared to that of hand-weeding. As expected, hand-weeding nearly eliminated all weeds. In contrast, grit-weeding achieved about 90% control of broadleaf weeds, only 15% control of grass weeds, and 70 to 80% control of all weeds. Much of the time and amount of grit used was devoted to suppressing grass weeds. Relatively soft corn cob grit easily abraded and controlled broadleaf weeds. However, harder and more angular grit materials may be needed to control annual and perennial grasses. Original source.
