1. Duryea, M.L. and S.K. Omi. 1987. Top pruning Douglas-fir
seedlings: morphology, physiology, and field performance.
Canadian-Journal-of-Forest-Research 17(11): 1371-1378.
Keywords: nursery operations
nursery pruning
tree phenology
tree/stand health
growth
yield
Abstract:
Seedlings from 9 seed sources at 6 nurseries in Washington, Oregon and
California were treated with various pruning treatments including tall and
short ht. (25 and 15 cm, respectively), early and late timing (6 wk after bud
burst or 6 wk after bud set, respectively), pruning twice or no pruning.
Seedlings were evaluated for phenology and quality,
and graded in the nursery. For each seed source, seedlings were planted at
field sites in their own zone and on one common site. Seedlings pruned tall and
early began growing again within 5 wk and set buds 2 wk later than unpruned seedlings. Shippable yield of seedlings pruned
tall and early and of unpruned seedlings were n.s.d, although more pruned seedlings had multiple leaders.
Pruned seedlings were smaller than unpruned seedlings
at the time of planting. Survival and growth were the same for pruned and unpruned seedlings in the 1st year after planting. Pruned
seedlings grew more than unpruned seedlings in the
2nd year, but were still shorter after 2 yr. Field growth was greater in
seedlings pruned tall or early than in seedlings pruned short or late. It is
concluded that pruning should be continued as a cultural practice if it
benefits nurseries, but that late short pruning should be avoided.