Pecan production increased by larger vegetation-free area surrounding the tree

Vegetation control with herbicides is a common practice in pecan [Carya illinoinensis (Wangenh.) K. Koch] orchards that benefits both non-bearing and bearing trees. However, the appropriate size for the vegetation-free area surrounding bearing trees had not been resolved. Vegetation-free circles centered on the Tree 0, 0.9, 1.8, 3.7, and 7.3m in diameter were established at planting and tree performance evaluated. This study reports the first six years of production that began in the sixth growing season. Yield was not affected by treatment in the first two years of production while yield was low and some trees had not begun to produce. The next four years were characterized by a strong positive relationship between vegetation-free diameter with annual yield and with cumulative yield. Weight per nut and kernel percentage were rarely affected by treatment. Leaf elemental concentrations of selected essential nutrients were not affected by treatment. Trunk diameter was similar among treatments each year. This indicates that yield was improved by the vegetation-free area impacting pistillate flower induction or flower and fruit retention rather than improved tree growth increasing the bearing surface. Published by Elsevier B.V.