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- Author or Editor: Jon T. Biermacher x
Pecan (Carya illinoinensis) trees were pruned using varying intensities at planting to determine the effect of pruning on trunk development and shoot growth. Data on trunk diameter, number and length of shoots, as well as the total shoot growth were recorded annually from a completely randomized design experiment that assigned 0%, 50%, and 75% pruning of above-ground height to single-trunk transplants. The results suggest that pruning intensity has little effect on trunk diameter. The pruned trees had fewer shoots initially and more growth per shoot, leading to a difference of 7 cm/shoot higher for the 50% pruning group than the control group and to a difference of 11 cm/shoot higher for the 75% pruning group compared with the control group. The total length of all shoots was not significantly different across treatments. Because previous research has sometimes shown that pruning increases tree survival and this research shows that trees can recover from pruning, there is no need to change the current recommendation of pruning seedlings at planting.
When trees with taproots are grown in containers, the taproot typically spirals around the bottom of the container. Currently, there is no consensus on what is the best thing to do about it. Pecan (Carya illinoinensis) grafted container-grown trees were transplanted under three treatment conditions. The treatments were container trees 1) planted straight from the container with no root pruning and no disturbance, 2) planted with taproots pruned so they no longer curled around the bottom of the container and with minimal disturbance of the root ball, and 3) planted with taproot pruned and all potting medium removed. Trunk size and shoot growth were recorded for each tree in each year during the first 4 posttransplant years (2010–14). There was no statistically significant effect of the treatments on trunk size. Shoot growth was slowed during the first year for trees with taproot pruned and potting medium removed, but there was no significant effect over the entire 4-year period.
Although irrigation is a common practice in pecan (Carya illinoinensis) orchards, the effects of different methods of irrigation on young tree growth, nut quality, and nutrient uptake have not been estimated. Five irrigation systems and one nonirrigated control system were established. Tree performance was characterized by change in trunk diameter, weight per nut, average kernel percentage, and total trunk diameter growth. Nutrient uptake was determined by foliar levels. The five irrigation systems were a microsprinkler with a 35-ft diameter, a microsprinkler with a 70-ft diameter, two subsurface driplines irrigating for 2 days/week alternating between water for 2 hours and no water for 2 hours, two subsurface driplines irrigating 1 day/week for 20 hours continuously (LI2), and four subsurface driplines irrigating for 10 hours continuously for 1 day/week (LI4). Irrigation systems affected foliar levels of potassium (K), boron (B), and manganese (Mn) levels. Irrigation system did not affect change in trunk diameter or kernel percentage. A spatial Durbin error model was estimated to use trunk diameter estimates from all trees in the orchard. This model found the trunk diameters of nonirrigated and LI4 system trees to be significantly less than those trees that were irrigated by the LI2 system. When observations were pooled over all years, LI4 trees had individual pecan nut weights that were significantly less than all other systems.