Size of the vegetation-free area surrounding pecan trees in a tall fescue sod affects production

• Initial tree growth and yield was optimal using 3.6 m vegetation-free circles.
• Older trees required 7.2 m vegetation-free circles for optimal production.
• Nut quality was similar regardless of distance between the tree and ground cover.

Vegetation control with herbicides is a common practice in pecan [Carya illinoinensis (Wangenh.) K. Koch] orchards benefiting both non-bearing and bearing trees. However, the appropriate size for the vegetation-free area surrounding bearing trees has not been resolved. Vegetation-free circles centered on the tree 0, 0.91, 1.83, 3.66, and 7.32 m in diameter were established at planting in a tall fescue (Festuca arundinacea Shreb. cv. Kentucky 31) sod. Tree performance was evaluated through the seventh production year. Performance of non-bearing trees was reported earlier. Growth of bearing trees improved as the diameter of the vegetation-free circle increased to 3.66 m. Yield was greatest when the size of the vegetation-free circle was 3.66 m or larger during the first three years of production. During the fourth and sixth crops trees with 7.32 m vegetation-free circles produced the greatest yields. The seventh year production was similar among vegetation control treatments. Measured nut quality attributes were not affected by the size of the vegetation-free area, but varied among years.