Although spring and summer pruning to various heights reduced diameter growth for the treatment year, diameter increment of most pruned trees did not differ significantly from that of controls 2 years after treatment. Total diameter growth during the test period was significantly less for pruned trees than for controls. Epicormic branching increased with spring treatments and with greater pruning heights. Pruning is apparently necessary to obtain high-quality stems. Summer prunings are preferable to spring ones, and no more than one-third of the total height measured during the dormant season should be pruned.
Krinard, Roger M. 1976. Growth and Branching of Young Cottonwoods After Pruning. Res. Note SO-208. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 3 p.