Management Information
Physical: Other management techniques include clearing and burning infested trees. Infested trees can be cut in winter when the nymphs are still present, and infested material should be burned on-site to eliminate the risk of future contamination. Bark should be stripped from felled trees before transporting to non-infested regions.
Chemical: Spraying of individual trees from the ground with lindane has proved effective for control, but spraying is warranted only in accessible areas supporting relatively high-value trees. Some of the chemicals that are effective on A. piceae are Asana XL, horticultural oil, insecticidal soap, Lorsban 4E. Asana and lindane can be used any time of year that trees can be treated. Lorsban and insecticidal soap should only be used from November through March in the USA. Any other time of year, a second application is necessary after four weeks. Horticultural oil should only be used from December through February (winter) as it may burn trees if they are not dormant. Lindane and Asana may cause an outbreak of the spruce spider mite as they kill mite predators. When using these chemicals in the spring, summer or fall, consider adding a miticide to the spray mix.
Biological: On stem-attacked trees that survive more than 1 or 2 years, A. piceae may be controlled by the tree itself. The outer bark may die in increasingly large patches, and a wound layer of still living, but impermeable bark may be formed. The population then is increasingly restricted to a smaller and smaller area until most insects die. The tree also produces juvenile hormone analogs that may reduce adelgid populations.
No parasites of A. piceae are known, but many predaceous enemies have been noted. Unfortunately, most of them are general feeders and unreliable. To remedy the lack of effective native predators, several species of insect predators have been introduced to North America from other parts of the world, six of which from Europe have become established. Three are beetles (Laricobius erichsonii, Pullus impexus, and Aphidecta obliterata), and three are flies (Aphidoletes thompsoni, Cremifania nigrocellulata, and Leucopis obscura). As yet, none of these predators have achieved detectable control. They appear to feed on A. piceae lifecycle stages that are unimportant in determining the trend in its population.
Management Resources/Links
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