Time to Treat Those Hemlocks

By on February 1, 2017

Time to treat those hemlocks for Hemlock Woolly Adelgid

Landscape & Garden Editor Kevin Johnson Warns Us About the Resurgence of the Hemlock Woolly Adelgid


The Hemlock Woolly Adelgid, a non-native invasive insect, was first discovered in Georgia in 2003. By 2009 it had spread to many counties across north Georgia and my company, Green Leaf Lawn and Ornamental, was the first in Georgia offering treatment for Hemlock Woolly Adelgid. I had become familiar with the treatment of Woolly Adelgid while serving as Grounds Supervisor at Young Harris College and I’ve now been chasing this insect around north Georgia and North Carolina for well over a decade. In the past I’ve written articles describing specific details about Woolly Adelgid and its impact on our environment. However, this time I thought I would share general information about my experiences in battling this insect over the last 10+ years, and what I see happening today to our Hemlock Trees.

Several years ago a meeting was held to gather and share information about the Woolly Adelgid and the relevant treatments. The Georgia Forest Service, Green Leaf Lawn and Ornamental and other organizations were there along with concerned property owners. At that time, it was estimated by some, that within 3-5 years of exposure to Woolly Adelgid that the Hemlock would die. It was also though that treatments with 75% Imidacloprid (standard ground treatment) would only last around 3 or so years. These were speculations based on the information available at the time. Since then, my experience has been a little different than those predictions.


Do untreated Hemlocks die in three years? While Hemlocks don’t typically die in as little as three to five years as some predicted, they do become decimated after several years of exposure. I continue to get called onto properties that have never been treated for Woolly Adelgid. While untreated Hemlocks may still be alive at this stage in the game, in many cases they are severely compromised. Some will have as little as 5-10% of their needles left. I looked at a property last year that I estimate had 100 untreated Hemlocks on it. I chose to treat only the 15 trees that I thought I could recover. It’s a sad situation for untreated Hemlocks.


How about length of control? Typically, a professional treatment of your Hemlocks should last roughly a minimum of five years. I’ve treated many properties where the treatment has lasted six or more years. Not a bad deal considering the original prediction was at a minimum three years. Not many lawn or tree applications can offer that kind of control.

Going Forward. What happens even if Hemlocks have been treated? Five years after treatment, what eventually happens, is that the insect is reintroduced to the Hemlock trees and they become infested all over again. Therefore, even if you had your trees treated five years ago, it is imperative that you have your Hemlocks inspected– and then be prepared to have them treated again. Sadly, the Hemlock Woolly Adelgid is still with us, and unfortunately, will be here for years to come.

Kevin Johnson is the owner of Green Leaf Lawn and Ornamental, LLC, based in Blue Ridge. For more information about the devastating hemlock woolly adelgid and treatment options, Kevin can be reached toll free at 866. 883. 2420 or by email at growitgreen@etcmail.com. Or check out his web site at www.wetreatlawns.com or visit www.hemlocks.org for more info.