Landscape Architect & Specifier News

MAR 2018

LASN is a photographically oriented, professional journal featuring topics of concern and state-of-the-art projects designed or influenced by registered Landscape Architects.

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114 Landscape Architect and Specifier News I n f o r m a t i o n R e q u e s t # 6 7 7 Wooly Adelgid Affects Vast Majority of North American Hemlocks It is estimated that 90% of the total geographic range of hemlocks in North America has been affected by the hemlock wooly adelgid (HWA). Native to Eastern Asia, the hemlock woolly adelgid was first discovered in the U.S. in 1951 in Richmond, Virginia. It is a very small pest that can have dire consequences on the eastern hemlock, Tsuga canadensis, and the Carolina hemlock, Tsuga caroliniana, two tree species that are found throughout the eastern U.S. These insects feed on the sap of hemlock trees by inserting their long stylets into the trunk of a tree, very similar to the spotted lanternfly's feeding habits ( www. php?number=29756 ). While a single insect itself is only about 0.8 millimeters in length, groups of them are easily visible and look like small cotton balls clustered together on the branches of hemlock trees. If a tree is infested, the HWA can take approximately 4 to 10 years to completely kill the tree. The HWA will cause the tree to lose its needles and prohibit any new growth. Furthermore, if the tree naturally withstands the infestation, it will be more likely to succumb to other secondary diseases. The North Carolina Cooperative Extension Service (CES) from the campus of North Carolina State University notes: "If the tree is severely defoliated, soil or trunk injections with an insecticide will probably not work well. Spraying lower branches will give the tree the best chance at recovery." For more on this pest and addressing the disease, visit the N.C. CES at ( https:// ). The small white cotton ball looking puffs on this hemlock's branches are hemlock wooly adelgids (HWAs). The safest insecticides for controlling HWA are foliar sprays with either horticultural oil or insecticidal soap.

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