Vol. 51—1997 - NorthEastern Weed Science Society

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Treatments and p~nting
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Ten perceJt granular hexazinone (PRONONE lOG, 1, 2, and 4 kg ai/ha) and 5%
granular hexazinone (PRONONE 50, 2 kg ai/ha) were applied on May 27, 1986 using a
skidder fitted witli a hydraulic blower unit (OMNI system) designed for application of
granular herbicid~S. Liquid hexazinone (VELPAR L, 2 kg ailha) was applied in 364 llha
water on May 29,: 1986 using a skidder-mounted hydraulic sprayer, equipped with a cluster
nozzle. PRONO~ lOG (2 kg ai/ha) and VELPAR L (2 kg ailha, 4361/ha) were applied on
September 18, 1986 using the same skidder-mounted application equipment.
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Controls ~d half of each spring hexazinone plot (split-plot design) were planted (2.1
m spacing) in JUIle 1986 and in June 1987 with local 2+2, bareroot black spruce seedlings
obtained from th~ Irving nursery. Fall hexazinone plots were planted in June 1987 with the
same bareroot stfk. A total of 480 (i.e., 80 per treatment) seedlings planted in 1986 and 640
seedlings planted!in 1987 were randomly selected and staked for yearly measurement.
Measurements an~
analysis
Seedling ~urviVal (%), height (em), and basal stem diameter (mm) were measured
annually (August). Stem volume (em") was computed using the formula for a cone: areal3 x
length = 1/3 x pilx r x height (1). Cover (%) of the dominant competitor, raspberry, was
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estimated visuallt within a Lrn radius of each staked seedling to the nearest 5% value. The
height of raspberty stems within each quadrant of the circle was measured to the nearest em.
Analyses ~f variance (ANOVA's) were performed on black spruce seedling growth
and raspberry competition data. Treatment means were compared via Tukey' s Studentized
Range (HSD) Te~t at 5% level of significance. The frequency of occurrence of live seedlings
was compared with a Likelihood Ratio Chi-Squared (O-Squared) Test (23). Regression
analyses were pefformed on 5th-year seedling growth vs. raspberry cover or height. Where
slopes were judgFd to be statistically significant, analyses of covariance (ANCOVA) were
performed to establish significant treatment differences due to planting time, treatment time,
or formulation. .
RESULTS
By Augu~t 1991 (i.e., six growing seasons after treatment [OSATD, mean raspberry
cover had increased to 92% in untreated plots (Table 1), and was greater than in spring plots
(P = 0.008) treatfd with granular hexazinone at 4 kg ailha (32%) or in fall (i.e., 50SAT)
plots (P =0.013~ treated with liquid or granular hexazinone at 2 kg ailha (42% each). No
treatment difference in raspberry height was observed in 1991. No differences in raspberry
control (cover o~ height), attributable to formulation (5% granular vs. 10% granular vs. liquid
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at 2 kg ailha), 1re observed throughout this study.
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