An evergreen in a garden always reminds us that hope sticks around, even in winter.
There are more than 250 registered cultivars of hemlock in existence. These Hemlocks vary in color, shape, leaf type, and much more.
Hemlock has a unique quality that other evergreens don’t, because they grow well in the shade. Yews can endure shade but don’t have the structure and beauty of a true hemlock tree.
The main challenge with hemlock is that the younger trees require extra care during the drought times of the year for the first four years.
After that the tree becomes very tough. Colorado Blue Spruce, on the other hand, is always at risk to Roundup drift. In other words, you will always have to be aware of Roundup drift from nearby farms. Hemlock has greater tolerance to chemical drift.
The scientific name for Eastern Hemlock is Tsuga canadensis.
I’m writing this for one my neighbors who planted young Hemlocks, and for anyone needing this information.
I remember seeing a beautiful stand of hemlocks while hiking in the ravines in Hocking Hills years ago. I won’t forget the smells and the coolness in the forest as we hiked the trails on a hot day.
Locally, you will find Hemlock at Mohican State Park and a few trails. If you get a chance to hike some of those trails, you will never forget these beautiful trees. In the cool moist ravines, hemlocks can grow to 100 feet tall, and live for century.
What’s really spectacular is that 100-plus different bird species nest in these trees. When you see one of these giants, you will understand why hiking in the heat in the middle of summer is not out of bounds because these trees provide dense shade that moderates temperatures. Their dense shade keeps things cool.
I recently noticed that Hemlock Woolly Adelgids are still considered pests in Ashland, Richland, Knox, and Wayne counties. These insects are aphid relative and are native to East Asia, where they don’t cause much trouble for hemlocks.
Since HWA arrived in the 1950s, this insect had no predator and no plant with natural resistance to stop them. As a result caused significant damage to many hemlocks farther east.
Two hemlock species are suffering. Both the Eastern Hemlock and the Carolina Hemlock are being affected. If you are hiking through the woods, you may see serious damage on these trees.
Like other aphids, the Hemlock Woolly Adelgid has a needle-like mouth part stylet or proboscis that pierces the base of the hemlock needle and feeds on the tree’s sap.
These insects reproduce asexually, which means they reproduce quickly. At their peak, you will find two or more insects on every hemlock needle. Together, they can look like cotton balls all over your trees.
As these insects feed on the tree, the nutrients in the tree declines and weakens. These insects can wage such a battle that they can kill trees in as little as two years. If hemlocks disappear forests change. Without the hemlocks the micro-climates they create, the nature of the forest changes.
These insects are spreading at 15 to 20 miles per year and moving north. It almost feels inevitable that we shall see HWA at Mohican State Park in a big way soon. That means the Oaks, Maples, and Birch will come in, and the potential non-natives will take over.
Can you imagine Mohican without hemlocks?
Several solutions exist for this insect. In North Carolina, biologists discovered a predator, a black lady bug called Laricobius nigrinus, in 1992 and brought it to Ohio to encourage it to come along. This insect will help establish sustainable landscapes to address this problem.
The 1995 and 1997 experiments in Connecticut and Virginia showed a reduction in adelgid densities from 47 percent to 88 percent within five months of introduction.
Because this pest has no natural controls, the Department of Natural Resources introduced this black beetle, called Laricobius nigris, from 2003 to 2005 in 22 different localities from Georgia to Massachusetts.
Sites were chosen based on adelgid strength in the area, infestation zones, and season. In their study, the introduced beetle did better in zones with milder temperatures. The experiments revealed a significant effect on the pest insect.
The black ladybug beetle eats the pest’s eggs.
There are also chemical solutions. Don’t treat these trees yourself. Notify the Ohio Department of Natural Resources, and they will apply the proper measures.
This tiny black beetle predates this HWA effectively in Connecticut. This should give us hope here in Ohio.
As you take your stroll through your garden this week, please keep your eyes open, and if you have any challenges, email me at ericlarson546@yahoo.com.