Wh. Fogal et al., REPRODUCTIVE DEVELOPMENT AND INSECT DAMAGE ON WHITE AND BLACK SPRUCE SEED TREES TREATED WITH AMMONIUM-NITRATE AND CARBOFURAN, Canadian journal of forest research, 23(9), 1993, pp. 1786-1792
Granular ammonium nitrate and carbofuran were applied to soil beneath
white spruce (Picea glauca (Moench) Voss) and black spruce (Picea mari
ana (Mill.) B.S.P.) seed trees to stimulate reproductive development a
nd protect them from defoliating and cone-feeding insects. Rates of ca
rbofuran application were 0, 10.8, or 21.6 g/cm DBH for white spruce,
and 0, 5, or 10 g/cm DBH for black spruce. Both species received 0, 22
4, or 448 kg N/ha of ammonium nitrate. Trees were assessed for defolia
tion by the eastern spruce budworm (Choristoneura fumiferana Clem.), c
one insect damage, seed-cone bud production, cone production, seed yie
lds, and needle senescence for 3 years in white spruce, and 2 years in
black spruce. On white spruce, carbofuran reduced defoliation and num
ber of spruce budworm at both application rates in the year of treatme
nt and at the, high rate in the second year; no protection was observe
d in the third year. Seed-cone bud production was stimulated by carbof
uran for 3 years following treatment. Needle senescence was increased
by carbofuran. Ammonium nitrate decreased needle senescence but had no
effects on other assessment variables. On black spruce, carbofuran di
d not reduce spruce budworm numbers or protect cones in the year of ap
plication but, in the year after treatment, both foliage and cones wer
e protected. Defoliation was reduced by the low rate of applied ammoni
um nitrate. Treatments did not influence the number of seed-cone buds
or cones or amount of needle senescence in black spruce.