EFFECTS OF WEED CONTROL METHOD ON GROWTH, YIELD AND FRUIT QUALITY OF `McINTOSH' APPLE TREES.
The growth and fruiting of 10-year-old `Mcintosh'/M.7 apple trees were compared under the following weed management systems: 1)untreated control; 2) herbicide spray (paraquat + oryzalin); 3) rotary tilling applied in May, June and July; 4) rotary tilling plus herbicide (oryzalin); 5) rotary tilling plus oats sown in August. All weed control methods increased tree growth compared to the untreated control over three years. Yield and fruit size were increased by the herbicide and the rotary tilled treatment. Rotary tilling plus herbicide increased yield but fruit size was larger than controls in 1990 only. Rotary tilling plus oats produced yield and fruit size equivalent to the control. In 1989 and 1990 rotary tilling alone provided less weed control compared to the herbicide treatment, while in July 1991, the reverse was true. Rotary tilling with herbicide and with oats have demonstrated weed control comparable to or better than the herbicide treatment except for the rotary tilled plus oats treatment in 1990. There were no differences among treatments in fruit color, maturity and percent soluble solids.