Environmentalists host workshop on protecting state tree
Pennsylvania’s state tree is the hemlock, a native species found all over the state. Since the 1950s, the hemlock woolly adelgid has been spreading throughout the state as well, but the insect is an invasive species that can kill a hemlock tree in a matter of years.
On Wednesday, the Butler City Shade Tree Commission hosted a workshop where arborists and pesticide applicators showed people how they could protect their hemlock trees from the adelgid.
Mark Ware, northeast technical adviser for Rainbow Ecoscience, said that because the adelgid is invasive, it has no natural predators and nothing to keep it from multiplying, aside from human intervention.
“The trees have had no reason to evolve and adapt to develop resistance to these pests because they have never had to deal with them before,” Ware said. “One of the treatment strategies we showed Wednesday is we put pesticides directly into the tree, so there is no pesticide exposure to the air; it goes right into the tree.”
Diane Smith, chairwoman of the City Shade Tree Commission, said about 35 people attended the workshop that took place on Franklin Street in the city. She said the methods Ware and Bob Dolan, tri-state territory manager for Rainbow Ecoscience, showed attendees were not only to deter the adelgid, but keep it from spreading when spotted.
“First you have to be aware of it, then you need to find what to do with it,” Smith said. “What they are doing is training the people who apply this stuff.”
Dolan said the adelgid’s body is seldom seen in full in the wild, because when it feasts on a hemlock tree, it forms a cotton-like shell around it that acts as a protective shield.
However, people can spot the effects the insect has on hemlock trees. Dolan said a tree being eaten by hemlocks will first lose its pine needles, then the affected area will begin turning yellow before it finally shrivels and rots.
Stopping the adelgid through preventative methods can save a tree before it dies.
“Up until about 30 percent of the canopy being dead you can save (a hemlock),” Dolan said. “Rather than waiting for the branches and needles to start yellowing, just scanning them pretty quickly you can see if they are infested.”
Ware and Dolan demonstrated five methods people could use to prevent adelgids from infesting a tree. Adelgids kill hemlock trees by using their mouths to pierce the bark, and then sucking out the tree’s nutrients.
Some of the methods involve injecting the tree’s vascular system with pesticides, which Ware said does not harm the environment in the same way spraying leaves can, but it may be inconvenient to the average person.
“Our beneficial population is left untouched, so it leaves that balance in place,” Ware said. “It is a time-consuming process, but the equipment can be pricey.”
People also could inject soil with certain chemicals the tree’s roots will absorb, or spray the bark around the tree stump with chemicals that will act in a similar way to the injection. Dolan said some of these chemicals can be found at hardware stores, but again, professional exterminators or arborists are recommended.
Dolan also said these processes are typically performed by professionals for optimal effectiveness, but they can be done by anyone with the right equipment and knowledge.
When done right, these methods can temporarily keep adelgids away from hemlocks.
“The woolly adelgid completes its life cycle twice a year, so if you can finish off the first round you should be good for the year,” Dolan said.
Hemlock trees are important not only to Pennsylvania culture. Ware said their environmental benefits extend to humans, as well as the natural ecosystems in which they exist.
“They act as a natural water filter, and downstream you get much better water quality,” Ware said. “They provide shade in the summer to help regulate temperatures for fish to nest under.”
