Can. Ent. 123: 295-298 (1991)

Gibberellic acid (GA) and naphthaleneacetic acid (NAA) were applied alone and in combination to both girdled and nongirdled branches of Douglas-fir in four seed orchards (two containing seedlings and two containing grafts). GA significantly increased seed-cone buds and cones and caused a nonsignificant increase in pollen-cone buds. Cone production was not significantly affected by girdling or the application of NAA. Trees treated with the combination of GA + NAA responded similarly to those treated with GA alone. Cone production response to GA varied according to the orchard locations, with better response in the normally more productive orchards. The percentage of trees flowering was increased by GA. Hormone treatments had no effect on seeds per cone but they significantly reduced filled seed per cone. Owing to increased cone number, however, the GA treatments greatly increased the yield of viable seed. NAA increased the percentage of seed germinating and the rate of seed germination, while GA had no effect.

Norwegian pipe traps, used with pheromones to mass-trap Ips typographus (L.) in Scandinavia, were used in central British Columbia to determine whether any native beetles would respond to the pheromone of I. typographus. The spruce-infesting Ips tridens (Mannerheim) was the only species captured. Traps baited with “Ipslure” packets (1400 mg 2-methyl-3-buten-2-ol, 70 mg (S)-(−)-cis-verbenol, 15 mg racemic ipsdienol), ipsdienol, or ipsdienol plus cis-verbenol, caught significantly more beetles than unbaited traps. cis-Verbenol, which attracted no beetles when used alone, acted synergistically when added to ipsdienol. Methylbutenol used alone was no more attractive to beetles than the control, and inhibited the response of female beetles when added to traps baited with ipsdienol or ipsdienol plus cis-verbenol. Ipsenol alone attracted no beetles. The sex ratios of responding beetles (mean 1 male: 7.15 females) did not differ among treatments, but all differed significantly from the ratio of 1 male: 3.12 female beetles emerging from naturally infested spruce bolts.

White spruce seedlings (seed source, 58°50′ N) were grown in a container nursery at Victoria, B.C. (48°28′ N) under the following two photoperiod regimes: (i) natural day length artifically extended to 18 h (120 lx from an incandescent source); (ii) natural day length with dark period interruption for 2.5 min every 30 min (120 lx from an incandescent source). Beginning on July 17, 12 weeks after sowing, batches of seedlings experienced a simulated failure of the lighting systems of from 0 to 9 nights. Although the reduced photoperiod did not fit the usual definition of a short day, failure of the lighting system in (i) and (ii) caused significant reductions in seedling shoot length and dry weight and a significant increase in root dry weight.

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