Adelgid Poison
The Hemlock wooly adelgid (Adelges tsugae) is a destructive little creature, causing devastation to evergreen forests from Canada, through the northeastern United States and southward into north Georgia. Within four years. Some tree species can survive longer although in a weakened state, making them susceptible to other pests and diseases.
Controlling this pest on a large scale, as in its natural habitat, is proving difficult but not impossible. A number of options are being explored which are not yet available to the homeowner. Still there are opportunities for those of us who enjoy hemlocks in our own gardens to protect the ones we have. Frequent visual monitoring of the undersides of the needles for small cottony masses is the best way to ensure catching this pest in the early stages of inhabitance. These will be visible on the twigs near the base of the needles. This “wool” is present during all stages of the adelgid’s development but is more noticeable in the spring.
Providing the proper growing environment is one the best way to protect hemlock trees. Hemlocks are shallow rooted and is susceptible to stress in low water situations. Provide up to one inch of water per week (including rainfall) slowly to the root zone. Fertilizing with a high nitrogen product is not recommended as it promotes the adelgid’s survival. Periodically applying a strong stream of water to the branches from April to June is capable of dislodging many of the egg and juvenile “crawlers”. These have little opportunity to find their way back to the tree and die. Pruning dead branches allows for better air circulation and promotes new growth. Heavy pruning is not recommended, however.
Horticultural oils and insecticidal soaps are my preferred method of control over all synthetic petrochemicals. Horticultural oil kills by suffocation as the fine oil coats the body while insecticidal soaps dry out vital fluids from soft bodied pests. They are relatively safer for the user and the environment and effective at every stage of the adelgid’s development.
There are a number of synthetic pesticides available to the homeowner for treating the Hemlock wooly adelgid. Others are only allowed to be administered by licensed arborists. Typically they will contain diazinon, fluvalinate, malathion. It is important to note that these pesticides are only necessary once an infestation has been identified as they are indiscriminate (nonselective) poisons, killing beneficials as well. I am not an advocate of their use.
Controlling this pest on a large scale, as in its natural habitat, is proving difficult but not impossible. A number of options are being explored which are not yet available to the homeowner. Still there are opportunities for those of us who enjoy hemlocks in our own gardens to protect the ones we have. Frequent visual monitoring of the undersides of the needles for small cottony masses is the best way to ensure catching this pest in the early stages of inhabitance. These will be visible on the twigs near the base of the needles. This “wool” is present during all stages of the adelgid’s development but is more noticeable in the spring.
Providing the proper growing environment is one the best way to protect hemlock trees. Hemlocks are shallow rooted and is susceptible to stress in low water situations. Provide up to one inch of water per week (including rainfall) slowly to the root zone. Fertilizing with a high nitrogen product is not recommended as it promotes the adelgid’s survival. Periodically applying a strong stream of water to the branches from April to June is capable of dislodging many of the egg and juvenile “crawlers”. These have little opportunity to find their way back to the tree and die. Pruning dead branches allows for better air circulation and promotes new growth. Heavy pruning is not recommended, however.
Horticultural oils and insecticidal soaps are my preferred method of control over all synthetic petrochemicals. Horticultural oil kills by suffocation as the fine oil coats the body while insecticidal soaps dry out vital fluids from soft bodied pests. They are relatively safer for the user and the environment and effective at every stage of the adelgid’s development.
There are a number of synthetic pesticides available to the homeowner for treating the Hemlock wooly adelgid. Others are only allowed to be administered by licensed arborists. Typically they will contain diazinon, fluvalinate, malathion. It is important to note that these pesticides are only necessary once an infestation has been identified as they are indiscriminate (nonselective) poisons, killing beneficials as well. I am not an advocate of their use.
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