Effect of the Amount of Dormant Pruning on Growth and Water Use of Containerized Crape Myrtle (Lagerstroemia × Fauriei ‘Tuscarora’)

Abstract

Abstract A study was conducted to determine the effects of different dormant pruning treatments on subsequent plant development and water use of crape myrtle (Lagerstroemia × Fauriei Koehne ‘Tuscarora’) transplanted into containers. Dormant, bare-root plants were pruned to the normal practice of a 30% reduction of existing shoot length by heading back and thinning of weak branches. Plants were randomly assigned to 3 pruning treatments including: 1) control—no further pruning, 2) shoot pruned—an additional 50% reduction of remaining shoot length for a total of 65% reduction in shoot length, or 3) a 50% reduction of root area in addition to the 30% reduction in shoot length. Fifty percent (50%) root pruning severely reduced earliness of bud-break and plant survival when compared to either the control or the 65% shoot pruning treatments. Earliest bud-break and highest plant survival were rated for plants in the 65% shoot pruned treatment. Plants in the 50% root pruned treatment had a significantly higher number of terminal shoots, but average shoot lengths were significantly shorter when compared to plants in the 65% shoot pruned treatment. At final harvest there were no significant differences in mean dry weights and leaf area, total shoot length, or average water use between treatments. However, a large plant to plant variation in growth and water use due to the pruning treatments was observed. Plants in the 50% root pruned treatment were less uniform in size and water use as compared to control plants or 65% shoot pruned plants which exhibited the greatest uniformity.