History
The Hemlock Woolly Adelgid was introduced into our area from an uncontained infection from Connecticut, and is capable of dramatically weakening and killing its host plants, both the Carolina Hemlock, and our local species, the Eastern hemlock.

This pest is capable of killing hemlocks in 3 to 5 years, especially if previously stressed. Recognizing it early, and taking the proper steps and control strategies will help protect and save your plant material.

Insect
HWA is a tiny insect, related to aphids, that produces woolly masses, hence its name.

Different from most other insect species, it is actually inactive during most of the growing season, but is very busy during the winter months. Existing as a nymph from mid July to mid October, HWA is found settled at the base of the hemlock needles. As they mature to adults, they closely resembling tiny puffs of white cotton, all lined up on the bases, similar to the cotton on Q-tips. Mid October, the insects aggressively feed using it piercing-sucking mouthparts to remove sap from the twigs of the host plant. The same tree could have many life stages present, and have two generations per year.

HWA is spread primarily by both wind and birds, but humans can do so as well if care is not taken when working around infected plant material.

Plants stressed out by horticultural or environmental factors (compacted soils, poor drainage, construction damage, drought prone, etc.) are much more likely to die from this pests attack.
Once found, management through spraying or injection is typically necessary.

Management
Addressed early enough, HWA is controllable. Horticultural oils can be used, and are typically recommended. Applied in spray form, the application must completely cover the entire plant, and may need to be reapplied if any of the insect is missed. Because of overspray, drift, repeated applications and other potential, we typically treat the plant material through other means.

We at Northeast Landscape prefer to inject, as the tree acts as its own receptacle to contain the material. We don’t have to worry about families walking by, spray landing in an area unintended (pools, on houses, etc.), as the material stays where it is-on the interior of the tree.

Imidacloprid is the pesticide of choice for control of HWA, and is translocated through the tree systemically via injection or done via soil drench (commonly done on trees less than 2” DBH (diameter at breast height). One injection can give up to 18months to 2 years control in some cases.

Injections holes are very small, and quickly callous over in the course of a growing season.

If you suspect that you have Hemlock Woolly Adelgid in your hemlocks, give us a call, and we will send out a representative to identify the insect and recommend a course of action.

It is important to note that once this insect is present in any given area, these adelgids will constantly pose a threat to all hemlocks, even those treated. It is therefore important to monitor your trees carefully several times a year, and treat as necessary.

Don’t take a chance with your plant material-be proactive in the health of your trees!
Contact Greener Lawns to Request a Quote or call 978-470-3111