The Combined Effects of Forest Tent Caterpillar Defoliation and Timber Stand Improvement Activity on Epicormic Sprouting of Sugar Maple and Black Cherry

A 2 × 2 factorial analysis of variance design assessed the combined effects of severe defoliation by the forest tent caterpillar, Malacosoma disstria (Hub.), from 1991 through 1993 and concurrent timber stand improvement (TSI) treatments on the occurrence of epicormic sproutingfor both sugar maple (SM), Acer saccharum (Marsh.) and black cherry (BC), Prunus serotina (Ehrh.) in the Tug Hill region of New York State. The potential economic effects of epicormic sprouting by dominant and codominant (DC) SM after defoliation and TSI were statistically significantbut negligible. TSI treatments alone and defoliation alone, however, promoted sprouting in intermediate SM, which may result in future grade reduction. The combination of defoliation and TSI treatment resulted in prolific epicormic sprouting by DC BC. These two disturbances have the potential to cause significant standwide value losses in this species.

Ten-Year Growth and Epicormic Sprouting Response of Western Larch to Pruning in Western Montana

Western larch (Larix occidentalis Nutt.) is a fast-growing, deciduous conifer that is often managed for timber production in the inland Northwest. No previous study has documented the response of this species to artificial pruning. Trees pruned as part of a pruning cost study in 1992 were followed for 10 years to assess growth and epicormic sprout response. Trees were pruned to two heights: 2.4 and 5.5 m in three stands in western Montana. Epicormic sprouting occurred in a majority of trees in the first 2 years after pruning, but subsequently many sprouts died so that by year 10, only approximately 30% of trees had sprouts. Volume increment was adversely affected by more severe pruning among smaller trees pruned to the shorter lift. The volume increment of the trees that received the 5.5 m lift was generally unaffected, but trees receiving the 2.4 m lift were more sensitive to pruning. Initial tree diameter and residual crown length were important variables in predicting the 10-year volume increment in pruned trees. West. J. Appl. For. 20(4):228–232.

Epicormic sprouting of pruned western larch

Western larch (Larix occidentalis Nutt.) trees in western Montana, U.S.A., were monitored for 6 years following pruning to assess incidence of epicormic sprouting. Trees were pruned to either 2.4 or 5.5 m. Epicormic sprouts were more prevalent in smaller diameter trees and in trees pruned to shorter live crown lengths than larger or longer crowned trees. Number of sprouts declined since pruning, but over 30% of trees still had epicormic sprouts 6 years after pruning. Sprouts that did not extend from the bole were prone to becoming dormant or dying over time. Extended sprouts were more persistent and will probably form wood-quality defects that remain outside the defect core. Pruning of western larch may still be successful for enhancing clearwood production if trees are pruned to retain at least a 50% live crown ratio and if pruning is delayed until trees reach about 16 cm diameter at breast height for a short pruning lift (2.4 m) or 22 cm for a higher pruning lift (5.5 m).

Hardwood Epicormic Branching—Small Knots but Large Losses

Epicormic sprouting was studied in a seed-tree regeneration cut and a selection cut, both made in mature, previously unmanaged, creek bottomland hardwoods in the lower coastal plain of South Carolina. The total exposure that seed trees received probably created near-ideal conditions for maximum epicormic sprouting, which allowed species to be ranked by sprouting propensity and degree of sprouting variation within species. Cherrybark oak produced the most sprouts, followed in descending order by swamp chestnut oak, Shumard oak, sweetgum, and yellow-poplar. White and green ash did not sprout, and Shumard oak and yellow-poplar were quite variable in sprouting incidence. The selection cut showed that in this stand, primarily composed of cherrybark oak and sweetgum, neither degree of release, crown class, nor direction of opening had an appreciable effect on sprout initiation or sprout numbers. Cherrybark oak sprouted less profusely than in the seed-tree cut, but sweetgum did not. Epicormic sprouting hazard is an important consideration in deciding whether to use some form of selection management. South. J. Appl. For. 10:217-220, Nov. 1986.