Cambial electrical resistance (CER) and periodic growth rate (PGR) of canopy balsam fir (Abiesbalsamea L.) trees were determined on 26 sites in Maine, New Hampshire, and Vermont, U.S.A., varying in level of spruce budworm defoliation. Determinations of water and potassium concentrations were made of the bark, wood, and vascular cambial zone (VCZ). Low CER was associated with high PGR and vice versa. A decline in PGR on all 26 sites was detected during early 1970's to late 1970's. It was not associated with, but may have been exacerbated by, spruce budworm defoliation. The most probable mechanism relating CER to PGR in balsam fir was variation in the thickness of VCZ and its correlation with potassium content. Thicker VCZ of faster growing trees released more potassium into the solution contacting electrodes than thinner VCZ of slower growing trees.

Cambial electrical resistance (CER) of more than 10 000 trees, predominantly balsam fir (Abiesbalsamea) and red spruce (Picearubens) was measured in 90 stands in northern Maine, New Hampshire, and Vermont, U.S.A. CER index values (mean CER, kiloohms per stand) ranged from 9 to 13 for fir in nonoutbreak situations, and 9 to 18 in outbreak situations with moderate to heavy budworm infestation, whereas values for red spruce remained essentially constant at 7 to 13 in both situations. Balsam fir trees in stands with an index value of 9 grew almost three times faster (diameter growth) than in stands with an index value of 13. An increase of index values from 13 to 18 in outbreak situations indicated no further reduction in growth, but may indicate impending mortality of trees with lower vitality. Such index values may be useful in developing a hazard rating system for fir stands infected with spruce budworm.

Growth and post-transplant establishment of half-sib seedlings from two elite sycamore (Platanus occidentalis L.) mother trees (Westvaco Corp.) and seedlings from a bulk seed lot from elite sweetgum (Liquidambar styraciflua L.) trees (Scott Paper Co.) were compared to that of seedlings from a native (Cookeville, TN) sycamore tree and a commercial source of sweetgum seeds. Seedlings were grown under standard field nursery conditions for two years, dug hare-root in autumn, and transplanted to another site to simulate landscape planting. Growth of elite seedlings during production was increased by 11 to 22% in height and 10 to 118 in caliper compared to that of conventional seed sources. Growth differences were maintained following transplanting. The primary lateral root number at transplanting was increased by 2 to 3 on elite sycamore seedlings compared to conventional seedlings. The number of pruning cuts required to eliminate multiple leaders tended to be less for elite seed sources. Survival did not differ among seed sources within a species.

Adaptability of forest tree improvement program seed sources to landscape nursery production and subsequent bare-root transplanting were investigated. Growth during two years of field production of seedlings from two elite half-sib families of sycamore (Platanus occidentalis L.) and a bulk open pollinated seed orchard mix of sweetgum (Liquidambar styraciflua L.) were compared with a commercially available seed source of sweetgum and a locally collected half-sib family of sycamore. Utilization of select half-sib families of sycamore resulted in 11% to 19% increases in height and an 11% increase in caliper during field production compared to the local seed source. Seedlings from elite half-sib families of sycamore resumed limited height and caliper growth during the year following transplanting while seedlings from the local seed source did not. Less pruning cuts were required to remove multiple leaders and large basal suckers on elite sycamore and sweetgum seedlings during production.