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| Where is it found? |
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- First found in Maine in 1908.
- In southern Nova Scotia in 1910.
- In southern New Brunswick in 1942.
- Spread to other parts of Atlantic Canada, eastern Quebec, southern British Columbia.
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| In Eastern Canada, outbreaks have caused significant
mortality to balsam fir.
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| IN 1947 |
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- 10-20 per cent mortality recorded in stands in Fredericton and Kings County.
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| 1950s – 1960s |
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- Ranked with the spruce budworm as a major cause of balsam fir mortality.
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| Although common in coastal areas, populations – particularly inland – have been much reduced since the mid-1960s to late-1980s. |
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| In the late 1980s – early 1990s, the Canadian Forest Service reported a slight increase in the occurrence in New Brunswick. However, the intensity of attack did not appear to change appreciably. |
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| Since 2000, increase in damage has been reported on individual trees and stands of balsam fir in southern New Brunswick. Visits by our staff to a number of these locations have confirmed the presence of lifestages and damage symptoms. |
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| Locations include mature stands, naturally regenerating areas, thinned stands (representing a substantial silvicultural investment) and individual or groups of trees on private property. Increases in damage have also been reported in neighboring jurisdictions. |
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| How it develops |
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- In New Brunswick, this pest primarily has two generations per year.
- A small proportion of the population (less than 10 per cent) may have three generations.
- The adult is less than two millimetres long, wingless and covered with a white wool-like material that it secretes.
- Each adult can lay up to 100 (more typically 30-60) pale red-brown eggs.
- These eggs are laid in clusters around its body beginning in late May – early June.
- Within a week or two, these eggs hatch into first stage nymphs called crawlers – the only mobile stage.
- During a seven to 14 day period, nymphs are dispersed to new locations by wind, birds, mammals and by crawling.
- During this time, they search for suitable feeding locations. (For example, thin bark, bark crevices, branch nodes, cone buds, flower scales.) They insert their tube-like mouthparts into the tree, and remain at this location for the rest of their lives.
- Development from the egg through three or four nymphal stages to adults takes about 14 weeks.
- New adults and eggs are present on host trees during the latter part of August or early September.
- The eggs hatch and second generation crawlers find suitable feeding sites. They attach themselves and remain at the same locations as nymphs from September to the following May. (This includes a dormant period of about 21 weeks in winter.)
- In spring, nymphs resume feeding and molt three times before becoming adults.
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| Balsam woolly adelgid lifestages can also be spread on
nursery stock and wood with bark.
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| Damage & signs of attack |
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- This pest feeds on tree sap found in the bark cortex.
- All age classes of balsam fir can be affected.
- When feeding, the insect secretes saliva into its host causing cellular changes in the wood.
- Both twigs and stems are attacked.
- Twigs that are attacked (crown attack) become thick and stubby or ‘gouty’ in appearance.
- Repeated twig attack can cause abnormal drooping of shoots, reduced height growth, flat tops, inhibited bud formation, thin crowns, crown dieback and – eventually – death of the tree from the top down.
- When the trunk or stem of the tree is attacked (stem attack), the tree produces compression wood.
- This wood is very hard and dark in appearance and limits the proper movement of water and nutrients in the tree.
- Trees can eventually die following three to four years of heavy stem attack (three adelgids / sq cm).
- White wool-like material found on the bark or twigs is another indication the insect is present.
- 'Gouty’ seedlings and understory trees are also an indication of its presence.
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| How to detect it |
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| In late April – early May* |
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- Collect a 30-45 cm mid-crown branch tip from each of three trees randomly selected at a location.
- Place branches in a bucket containing seven to 10 cm of water.
- Leave in a warm area for approximately five days.
- Use a magnifying glass to search for white wool-like masses. They are approximately two millimetres in size and are often found at the base of current-year buds, bud scales and branch nodes.
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| Once the insect is detected, watch for damage.
Controls may be required.
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| SOURCE: Nova Scotia Department of Natural Resources and Energy |
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| How to control |
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| Climate is the most important natural factor limiting pest populations. |
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- Overwintering mortality increases as temperatures dip below -20ºC.
- Temperatures of -35ºC or lower cause 100 per cent mortality.
- Late spring frosts also kill exposed feeding nymphs.
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| The balsam woolly adelgid has a number of insect predators. However, their role in reducing populations is limited, especially in areas where twig or crown attack is more prevalent. |
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| The following products have been used experimentally in Nova Scotia to control populations on small Christmas and ornamental trees. (Permethrin is the active ingredient.) |
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- Insecticidal soap. (For example, Safer’s insecticidal soap concentrate, Safer’s Trounce insecticide concentrate, Mintox Methoxychlor plus insecticidal soap Domestic, Green Earth organic insecticidal soap concentrate.)*
- Chemical insecticides. (For example, C-I-L Ambush tree & garden insect killer, Green Cross Gardal Permethrin for food & ornamental crops, bio-environmental permethrin water-based insecticide, Pounce emulsifiable concentrate insecticide.)*
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| Be certain to mix and use these products according to label directions. |
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| Nymphs that have overwintered are targeted for treatment in the early spring. |
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- Spraying should be conducted during a three or four week period prior to bud break.
- For best results, a dilute spray should be applied to all parts of the foliage and stem.
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| Over large forested areas |
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- Biological or chemical controls have been ineffective and impractical.
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| In stands next to infested areas |
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- Salvage cutting has been used to help reduce pest spread.
- Ensure trees are cut in late fall or winter when nymphs are immobile.
- Wood should be transported and processed before eggs and crawlers are present in the spring.
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| One publication suggests that overwintering nymphs do not survive on winter-cut branches and tops as they dry out too rapidly. Another recommends that this material be burned prior to spring to eliminate any danger of surviving lifestages. |
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| * Does not imply endorsement by Natural Resources nor discrimination against similar products. |
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| Our sources |
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- Annual Report of the Forest Insect Survey, Forest Insect Investigations. Department of Agriculture Canada, Division of Entomology, Science Service.
- Balsam Woolly Adelgid. Tree Pest Extension Service, Forestry Canada – Maritimes. Pest Control Leaflets: 23-26.
- Magasi, L.P. 1980. Forest Pest Conditions in the Maritimes in 1980.
- Maritime Forest Research Centre, Canadian Forestry Service, Environment Canada.
- Information Report M-X-118. Magasi, L.P. 1988. Forest Pest Conditions in the Maritimes in 1988.
- Maritime Forest Research Centre, Canadian Forestry Service, Environment Canada, Information Report M-X-174: 15-16.
- Martineau, R. 1984. Insects Harmful to Forest Trees.
- Canadian Forestry Service, Agriculture Canada. Catologue No. Fo 64-32/1984E: 92-95.
- Moore, Keith 2001. Balsam Woolly Adelgid Population Presence in True Fir Trees.
- Nova Scotia Department of Natural Resources, Insectary Notes March/April 2001: 6.
- Prebble, M.L. 1975. Aerial Control of Forest Insects in Canada. Environment Canada. Catalogue No. Fo23/19/1975: 250-253.
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| References: Anonymous, 1947. Annual Report of the Forest Insect Survey, Forest Insect Investigations. Department of Agriculture Canada, Division of Entomology, Science Service. Anonymous, 1989. Balsam Woolly Adelgid. Tree Pest Extension Service, Forestry Canada – Maritimes. Pest Control Leaflets: 23-26. Magasi, L.P. 1980. Forest Pest Conditions in the Maritimes in 1980. Maritime Forest Research Centre, Canadian Forestry Service, Environment Canada. Information Report M-X-118. Magasi, L.P. 1988. Forest Pest Conditions in the Maritimes in 1988. Maritime Forest Research Centre, Canadian Forestry Service, Environment Canada, Information Report M-X-174: 15-16. Martineau, R. 1984. Insects Harmful to Forest Trees. Canadian Forestry Service, Agriculture Canada. Catologue No. Fo 64-32/1984E: 92-95. Moore, Keith 2001. Balsam Woolly Adelgid Population Presence in True Fir Trees. Nova Scotia Department of Natural Resources, Insectary Notes March/April 2001: 6. Prebble, M.L. 1975. Aerial Control of Forest Insects in Canada. Environment Canada. Catalogue No. Fo23/19/1975: 250-253. |
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