Vol. 51—1997 - NorthEastern Weed Science Society

185
TABLE 2. Survival (%), 5 GSAP, of bareroot, black spruce seedlings planted after spring or
fall site preparation with liquid and granular hexazinone formulations.
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Treatment' Spring Treatment Fall Treatment
I Planted June 1986 Planted June 1987 Planted June 1987
CONTROL
10 % granular
1 kg ai/ha
2 kg ailha
4 kg ai/ha
S % granular
2 kg ai/ha
liquid
2 kg ai/ha
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86.4 a 67.2 b
70.0 b 80.0 a
63.0 b 88.9 a
66.7 b 60.0 b
73.8 b 80.0 a
82.5 a 76.0 a
67.2 b
85.0 a
69.5 a
a-b Numbers wi~hin columns followed by the same letter are not significantly different at the
5% level aCCOrdirg to G-Squared Test.
Fifth-yew! seedling stem volume was significantly correlated with raspberry
competition, decreasing as competition increased. All relationships were somewhat
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curvilinear, and J'ubsequent natural log transformations of stem volume data generally resulted
in better correla ions. Linear regressions relating 5th-yr black spruce seedling stem volume to
1990 or 1991 raspberry cover or height explained up to 72% of the variation in volume for
spring or fall treatments, and the best relationships were generally with raspberry height
(Figure 2). A linear regression model (i.e., includes control and 2 kg ai/ha treatments)
relating 5th-yr stPm volume to 1991 raspberry cover for seedlings planted 1 yr after spring
hexazinone treatlnents only explained 35% of the variation in stem volume, whereas the same
relationship wit~ raspberry height (Figure 2B) as a covariant explained 58% of the variation
in stem volume. i Analyses of covariance (ANCOV A) for possible treatment differences due to
planting time, (~igure 2A), treatment time (Figure 2B), and formulation (Figure 2C) revealed
no significant treatment differences.
DISCUSSION
Reducin~ raspberry competition with hexazinone enhanced black spruce survival and
growth for bareroot seedlings planted approximately 1 yr after spring hexazinone treatment.
Reducing raspberry competition with fall hexazinone treatment also enhanced black spruce
seedling survival and growth. Wood et al, (25) reported significant growth increases for
bareroot, black ,pruce seedlings planted at differing time intervals after site preparation with
liquid hexazinone (VELPAR L). Wood et al. (26) reported significant black spruce growth
increases for se~dlings planted in the spring after winter site preparation with PRONONE.
Sufficierjt rainfall was received in June 1986 (5.3 cm) to ensure the release of nearly
all hexazinone from PRONONE granules into the soil. Feng et a1. (5, 6) studied release of
hexazinone fro~ PRONONE lOG granules under both laboratory and field conditions. They
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