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Table 63
Table 64
B. Viruses: Application Clnd assessment 251
Application of EPV contaminated with NPV and CPV on six 1.07-ha plots using a helicopter
fitted with boom and nozzle equipment and calibrated to deliver 28.2 Ilha*
Population
Pre·dominant Deposit Highest virus infection (01.,) reduction due Current
Dosage. instar at card, to treatment year's foliage
PIB/ha time of droplets! EPV NPV CPV (%} saved ('Yo}
Plot (x 10") application cm 2 bF·· wS bF wS bF wS bF wS bF wS
1 750 2 10 9 38 10 0 7 0 40 R 15
2 75 2 9 3 16 0 12 1 4 0 61 3 0
3 7.5 2 9 1 12 0 2 II II 0 25 0 0
4 750 3&4 29 6 5 4 7 1 4 30 79 1 0
5 75 3&4 31 2 2 0 1 II II 48 57 0 0
6 7.5 3&4 NO··· 4 6 0 0 0 0 II 59 1 0
* Aqueous tank mix contained 2.5% IMC 90-001 sunlight protectant.
** bF = balsam fir, Abies balsamea (L.) Mill.; wS = white spruce, Picea glauca
(Moench) Voss.
••• ND = Not determined .
Follow-up studies were undertaken between 1972 and 1975 on the two plots treated
with the highest dosage (Table 64). It can be seen that, although there was little foliage
protection in 1971 (Table 63), there was significant foliage protection in the subsequent 3
years. Also, the NPV, which was a minor contaminant in the EPV preparation, was
considerably more prevalent in the following years than the EPV (Cunningham el al.
1975a).
Follow-up studies on two I?lots treated with EPV contaminated with NPV and CPV at a
dosage of 750 x to" inclUSIon bodieslha in 1971·
Population Current
Highest virus infection (%) reduction due "ear's
to virus oliage
EPV NPV CPV {%l saved {%}
Plot Year bF** wS bF wS bF wS bF wS bF wS
1972 0 5 7 19 2 5 64 82 72 59
1973 2 5 3 13 0 0 3 60 27 22
1974 1 2 1 4 0 0 0 5 29 49
1975 1 6 5 16 1 1 0 78 22 2
4 1972 0 0 17 20 to 4 16 68 44 49
1973 0 1 4 16 2 0 15 83 26 22
1974 0 1 3 11 1 0 0 48 25 40
1975 0 1 17 11 0 0 47 26 1 1
* See Table 63 for details and results in 1971
.* bF = balsam fir, Abies balsamea (L.) Mill.; wS
(Moench) Voss.
Entomopoxvirus
white spruce, Picea glauca
In 1972, pure EPV was tested and three plots with a total area of512 ha were treated. The
timing of the application was on second- and third-instar larvae, but an unseasonably
late snow fall destroyed most of the spruce budworm larvae and killed the new growth
on the trees. Population studies and defoliation estimates were abandoned and only