Temporal effects of chemical weed control on tart cherry tree growth, yield, and leaf nitrogen concentration

Abstract

This experiment was conducted to determine temporal weed management parameters for tart cherry (Prunus cerasus L.) orchards. Annual ryegrass (Lolium multiflorum L.) and lambsquarter (Chenopodium album L.) were planted in tree rows of a 4-year-old tart cherry orchard. Weeds either were not controlled or controlled with nonresidual herbicides during the following intervals: all-summer; May, June, July, or August; preharvest (April-July); or postharvest (late July to frost). Trees in all-summer, June, and preharvest weed-free plots had more shoot growth, more nodes, longer internodes, greater leaf area, and higher concentrations of leaf nitrogen than did those in the weedy control and postharvest, July, or August treatments. A larger increase in trunk circumference was observed in all-summer and preharvest weed-free plots than in postharvest and weedy plots. Early-summer weed control was important for tree vegetative growth. Tree yield (fruit weight and number) was greater on trees without weed competition postharvest than in those treated in May, June, July, or in weedy controls. Late-season (after late July) weed control is therefore important for fruit yield.