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Table 55
continued
Aclelge.\· ph-elle (Ratz.). 233
Year of
Species and province Year Origin Number recovery
Scymnus pumilio (Weise)
Newfoundland 1960 Australia 9687
New Brunswick 1959 Australia 5590
1960 Australia 7286
British Columbia 1960 Australia 2930
Telraphleps abdulghani Ghauri
Nova Scotia 1965 Pakistan 949
New Brunswick 1962 Pakistan 1972
1963 Pakistan I 157
1964 Pakistan 45
1965 India 278
Pakistan 2921
British Columbia 1965 India 19
Pakistan 1257
Tetraphleps raoi Ghauri
Nova Scotia 1965 India 59
New Brunswick 1965 India 59
• Species 'M'.
Attempts to control the adelgid with contact or systemic insecticides have been
unsuccessful. Several insecticides tested proved suitable for ornamental and nursery
applications where it was possible to saturate infested trees with chemical solutions.
However, not one of the 51 insecticides used in laboratory and greenhouse experiments
caused acceptable levels of adelgid mortality under field conditions (Nigam 1972, 1976).
Recently, some success has been obtained in controlling adelgids on individual trees
with insecticidal soaps (Puritch 1975). These chemicals are expected to be useful only
for ornamental and nursery applications.
There are no known insect parasites of the balsam woolly adelgid but several fungal
diseases have been reported. including Fllsarium larvaTllm Forbel and Cephalosporium
coccoTllm Petch found in the Gaspe region of Quebec (Smirnoff 1970), Cephalosporium
sp. and Penicillium sp. found in British Columbia (Harriset al. 1966), and F. nivale (Fries)
Cesati found on adelgids in North Carolina. USA (Fedde 1971). Greenhouse and field
experiments with the diseases from Quebec have been unsuccessful. The potential of
organisms from other locations as natural control agents remains unknown.
Failure to control the balsam woolly adelgid is viewed with special concern in Atlantic
Canada. In Nova Scotia and Prince Edward Island, balsam fir stands are usually
damaged before reaching a marketable size. On the island of Newfoundland, spectacular
and unprecedented mortality of balsam fir has occurred on an accelerated scale in stands
where adelgid attack has been followed by severe spruce budworm defoliation (Schooley
1981). In affected areas. stand conversion. i.e. the replacement of balsam fir with other
tree species, is being conducted on a large scale. Black spruce, Picea mariana (Mill.)
B.S.P., is the favoured alternate species but white spruce. P. glauca (Moench) Voss,
eastern larch. Larix larici"a (Du Roi) K. Koch. and hybrid larch species are being
considered.