Hemlock Woolly Adelgid

Just For Fun

Have you seen small white cottony balls on hemlock trees? If you have then that means those trees are infested with Hemlock woolly adelgid (HWA). Let’s look at why it’s important to preserve hemlocks, what is the pest that is killing them, and what you can do to save them. We are getting to the time of year when they really start to come out.

Hemlocks are a native species that ranges from Maine to Northern Alabama. They are a keystone species that provides habitat for about 120 species of vertebrates and over 90 species of birds. Hemlocks are unique in their ability to thrive in shade. This attribute makes them common in ravines and along rivers and streams. Their proximity to streams and rivers means that they are crucial in reducing erosion and watershed protection. Hemlocks can be identified by their needles. They have short flat needles with two distinctive pale white stripes on the underside. The needles are wider at the base and taper to a rounded tip, unlike firs that have parallel sides the whole way down.

HWA is a very small insect. The white cottony sacks on the hemlock trees are egg sacks of HWA. They are an invasive species from Asia that doesn’t have a natural predator here. HWA feeds on the sap inside of hemlock trees. Wind, birds, deer, or humans can spread the HWA. Once a tree has become infected, it will die within four to 10 years. Therefore, it is important to treat trees as soon as possible after finding that they have been infected.

It is important to treat your own trees with cultural and chemical controls. Cultural controls include keeping hemlocks well mulched and watered. Hemlock trees don’t have very deep roots and droughts can make them more susceptible to infection. Don’t place any bird feeders or deer feeders near your trees. Birds and deer can carry the eggs for long distances. If you are hiking in an area that has HWA wash your clothes afterward because you may be carrying eggs. Be careful to not over-fertilize your trees as that could make them more enticing to HWA. Cultural controls may keep your trees healthy, but when they become infested, chemical controls are the only option. Chemical controls involves treating your tree with either Imidacloprid or Dinotefuran, and is the most common and effective method of control. An imidacloprid treatment will last four or five years. However, it may take one year before it is effective. Dinotefuran will last for two years in the tree and will take about four to six weeks to take effect. The ideal way to apply either of these insecticides is by soil injection or soil drench. Putting the insecticide in the soil will mean quicker uptake by the plant and reduce the chance of off target drift. If the trees are near open water, a trunk injection of insecticide is necessary, which will require a professional. Whenever applying a pesticide it is important to familiarize yourself with the label before using the product. 

The Union and Towns County Extension Offices each have a soil injector that is available to be checked out. Checking it out requires a $250 dollar deposit that will be returned when the injector is brought back. I also have a soil drench kit in each office, which are simpler to use, especially if you don’t have many trees. You must provide your own insecticide. The organization Save Georgia’s Hemlocks have a website that has lots of information too.

Contact your local Extension Office or send me an email at [email protected] if you have any questions about HWA.

Tree Dormancy

Just For Fun

The leaves changing color and falling is a sign that colder weather is getting closer and closer. Trees are entering into dormancy. Dormancy is an important process to allow the tree to survive through the winter. Let’s talk a bit about how dormancy works in trees and why they need to do it.

Dormant trees will stop growing above the ground. Dormancy is partly brought on by temperature change, but even more so by the change in day length. The college word for this phenomenon is ‘photosensitive’, meaning the trees change in response to day length. Leaves will begin to change color and fall off. Leaves begin to change color because chlorophyll begins to break down. Chlorophyll is a green pigment that plants use to turn light energy to chemical energy. There are other pigments in the leaves too. As the chlorophyll breaks down the other pigments are left, resulting in the wide array of leaf color that we see. Evergreen trees like pine trees of hollies will have a needle drop in the fall and again in the spring. 

As we move into winter trees will enter what’s called endo-dormancy. In endo-dormancy an unsatisfied chill hours requirement will keep plants from waking back up. Different plants have a different number of chill hours, or hours spent below 45 degrees Fahrenheit. Chill hours are supposed to keep plants from waking back up too soon. In 2019, we had a couple of days in February that were over 70 degrees. While my pale legs might like to see some sun, February is not time for plants to begin waking up, as we have more freezes that are coming. Hopefully, those plants haven’t met their chill hour requirement, so even though I’m wearing shorts, the trees are still dormant.

Endo-dormancy also makes trees cold hardy. Trees will behave in a couple of different ways to make themselves cold hardy. One strategy that trees use is to keep all their water inside their cells. Frozen water expands. If all that water froze and expanded the cells would burst. To combat this trees move minerals and hormones in to mix with the water. Mixing water drops the freezing point, so that plants’ cells don’t freeze and burst. Another strategy is to move the water out of the cells so that it can freeze safely in the intracellular space.

When spring rolls around temperatures start to rise and trees will start to bud out because they have satisfied their chill hours requirement. However, if plants start to bud out and then we have another freeze, that can kill off the buds and cause damage to the trees. We saw that happen this year with a couple of freezes in April and then one on May 10. 

Evergreens will continue to need water throughout the winter. If the soil freezes for long periods, the roots can’t take up the water. Deciduous trees, trees that lose their leaves, will not need as much water. Roots in trees will continue to grow as long as soil temperatures are over 40 degrees. Soil temperatures are warmer than air temperatures in the winter because they are insulated.

If you have questions about trees and dormancy contact your County Extension Office or email me at [email protected]

Hemlock Woolly Adelgid

Community, Lifestyle
Hemlock Woolly Adelgid

Have you seen small white cottony balls on hemlock trees? If you have then that means those trees are infested with Hemlock woolly adelgid (HWA). Let’s look at why it’s important to preserve hemlocks, what is the pest that is killing them, and what you can do to save them. We are getting to the time of year when they really start to come out.

Hemlocks are a native species that ranges from Maine to Northern Alabama. They are a keystone species that provides habitat for about 120 species of vertebrates and over 90 species of birds. Hemlocks are unique in their ability to thrive in shade. This attribute makes them common in ravines and along rivers and streams. Their proximity to streams and rivers means that they are crucial in reducing erosion and watershed protection. Hemlocks can be identified by their needles. They have short flat needles with two distinctive pale white stripes on the underside. The needles are wider at the base and taper to a rounded tip, unlike firs that have parallel sides the whole way down.

HWA is a very small insect. The white cottony sacks on the hemlock trees are egg sacks of HWA. They are an invasive species from Asia that doesn’t have a natural predator here. HWA feeds on the sap inside of hemlock trees. Wind, birds, deer, or humans can spread the HWA. Once a tree has become infected, it will die within four to 10 years. Therefore, it is important to treat trees as soon as possible after finding that they have been infected.

It is important to treat your own trees with cultural and chemical controls. Cultural controls include keeping hemlocks well mulched and watered. Hemlock trees don’t have very deep roots and droughts can make them more susceptible to infection. Don’t place any bird feeders or deer feeders near your trees. Birds and deer can carry the eggs for long distances. If you are hiking in an area that has HWA wash your clothes afterward because you may be carrying eggs. Be careful to not over-fertilize your trees as that could make them more enticing to HWA. Cultural controls may keep your trees healthy, but when they become infested, chemical controls are the only option. Chemical controls involves treating your tree with either Imidacloprid or Dinotefuran, and is the most common and effective method of control. An imidacloprid treatment will last four or five years. However, it may take one year before it is effective. Dinotefuran will last for two years in the tree and will take about four to six weeks to take effect. The ideal way to apply either of these insecticides is by soil injection or soil drench. Putting the insecticide in the soil will mean quicker uptake by the plant and reduce the chance of off target drift. If the trees are near open water, a trunk injection of insecticide is necessary, which will require a professional. Whenever applying a pesticide it is important to familiarize yourself with the label before using the product. 

The Union and Towns County Extension Offices each have a soil injector that is available to be checked out. Checking it out requires a $250 dollar deposit that will be returned when the injector is brought back. I also have a soil drench kit in each office, which are simpler to use, especially if you don’t have many trees. You must provide your own insecticide.

Contact your local Extension Office or send me an email at [email protected] if you have any questions about HWA.

While you’re home, help your Hemlocks

Just For Fun

While many of you are sheltering at home, I hope you’re going outside every now and then to refresh yourself with
the sights, sounds, and smells of nature. Maybe you’re checking on the plants and wildlife around your home to see
how they’re faring this spring. And since we’ve just celebrated Earth Day, you may also be thinking about ways you
can help protect and improve our environment. So let me ask you to consider one very important component –
trees, and hemlock trees in particular.

Hemlocks, the native evergreen icon of the Appalachian region, play a vital role in preserving the natural beauty and
ecological health of our forests and waterways as well as the economic vitality of our communities. But millions of
hemlocks are dying because of an invasive insect, Hemlock Woolly Adelgid, that sucks the starches and other
nutrients from the needles, causing the trees to defoliate. Recognizable by the presence of tiny white egg sacs on the
underside of the branches, the infestation is in all of north Georgia and the Atlanta area.

The good news is that the hemlocks, even if already infested, can be treated and saved, and spring is the best time to
do it. The process is safe, highly effective, economical (especially compared to the cost of losing these valuable
evergreens), and easy enough for most property owners to do. There are also several properly qualified
professionals who can help.

Save Georgia’s Hemlocks is a 100% volunteer, 501(c)(3) nonprofit organization of concerned citizens dedicated to
preserving, conserving, and restoring endangered hemlocks through education and charitable service. They can
provide easy-to-follow instructions or a list of qualified professionals for property owners, training for volunteers
who want to help on our public lands, and a wide range of opportunities for individuals and groups to put the spirit
of Earth Day into action.

To learn more, visit www.savegeorgiashemlocks.org or call the Hemlock Help Line SM 706-429-8010.

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