(Last week I discussed the dangers facing the trees of North America. This is PART TWO of a series on Falling Giants. If you are new, please read PART ONE first.)
While it seems that all these trees are doomed, there is some hope for the future of our trees.
Bringing back a giant
Currently there is a breeding program by The American Chestnut Foundation to bring back this mast tree. The key to this program is the Chinese Chestnut. While Chinese chestnuts are infected with the blight, they are not killed by it. They are resistant to it. The Foundation is using Chinese chestnuts to help the American Chestnut resist the blight.
Using a backcrossing method, the Foundation is using the genetics to take the disease resistance of the Chinese chestnut and add it to the American Chestnut. Unfortunately, the resulting tree will not be 100% American Chestnut but it is as close to the American version as possible.
The American Chestnut foundation has planted these new chestnuts in the wild on public lands in Virginia, North Carolina and Tennessee. These trees are growing strong, have flowered early and are currently in their sixth generation. These trees are 15/16th American Chestnut and 1/16th Chinese chestnut.
In 2005, the first possibly blight-resistant chestnuts were harvested from these new trees. So far it has been good news as these chestnuts are growing well in the forest, competing as expected with other trees.
Researchers are taking a second approach in the fight for the American Chestnut. They are fighting the Chestnut blight itself. Native forest viruses are being used against the Chestnut blight. These ‘hypo viruses’ make the blight weak so that when the blight attacks a tree it is less dangerous. These viruses are being released into forests with the new chestnuts. It vaccinates the chestnuts against the real blight, protecting the trees.
Testing is still ongoing but there is hope that one day a chestnut will return to the eastern forests.
“Testing is still ongoing but there is hope that one day a chestnut will return to the eastern forests.”
Using naturally resistant trees
The American Elm also has had success in developing resistance to the Dutch Elm Disease.
In 1996 the American Elm varieties ‘Valley Forge’ and ‘New Harmony’ were introduced. Both are pure American Elms and have shown resistance matching that of the Asian elms. Bred by the Agricultural Resource Service in Maryland, these trees are similar to the ones lost. Currently there are 5 pure American elms that have shown resistance. In addition to the two mentioned there are ‘Princeton,’ ‘Prairie Expedition,’ and ‘St. Croix.’ Most of these trees are able to grow in zones 5 to 7, but ‘Prairie Expedition’ is good to zone 3.
The USDA Forest Service has not stopped here, they are currently seeking more surviving elms that may have resistance so that they can introduce genetic diversity into the species.
Battling beetles from Asia
Ash trees also have had good news. Some ash trees may be avoiding the Emerald Ash Borer. Recently scientists have found that the Blue Ash (F. quadrangulata)is naturally resistant to the Emerald Ash Borer. This tree grows from Michigan to Kentucky into Tennessee and Missouri. It is currently under study in hopes that it holds secret to saving other ash species.
“Recently scientists have found that the Blue Ash (F. quadrangulata)is naturally resistant to the Emerald Ash Borer. This tree grows from Michigan to Kentucky into Tennessee and Missouri. It is currently under study in hopes that it holds secret to saving other ash species.”
There is also an effort to trap the insects and kill them by using weakened ‘trap trees’ to attract the beetles. The trees are girdled (a ring of bark removed) and allowed to stand for the summer. In the winter the trees are debarked, exposing the beetles to predators and the cold, killing them.
In the battle against the Asian Longhorn Beetle the U.S. Department of Agriculture is optimistic. In a 2016 brief they stated that they are “confident that we will be able to eliminate the beetle in the three affected states using the strategies available to us. The goal is still to eradicate this non-native, tree-killing pest.”
The strategies mentioned are quarantine (308 square miles total in New York, Massachusetts and Ohio), year-round survey of host trees for infection, removal of infected trees and annual tree treatments. They are also encouraging residents not to remove plant materials from these areas.
Research is also ongoing to find ways to treat nursery stock, trap adult beetles and to understand its host trees.
Saving the redwoods of the east
Smoky Mountain National Park has not given up on their hemlocks. Through funding raised by the Save the Hemlocks initiative they are using a multistep approach to fight back. First they are spraying the branches with insecticidal soap in areas along roadways. This is a temporary measure, but is being used to control initial outbreaks of the adelgid.
They are also treating the trees systemically with insecticide. These insecticides are injected into the tree, or poured on the soil (soil drenching). Either way, the tree takes the insecticide into itself and then has an internal ‘poison’ against the adelgids. These treatments last 5 years and so far 200,000 trees in the park are protected in this manner.
The National Forest Service has also released half a million predators of the Hemlock Woolly Adelgid. One released species is a native to the northwestern United States and the other is from Asia. They have had great success with this and in 2005 they found that the beetles are reproducing and helping the trees. The park hopes that these predators can be used as a long-term solution.
Not giving up
The Mountain Pine Beetle may be stumping foresters some, but they haven’t given up. Experiments with synthetic pheromones used in hopes to repel or attract the beetles have failed. While some success has occurred with the use of topical insecticides to prevent beetle entry in early summer, it has been found that systemic insecticides cannot harm the beetle once they have entered the tree due to how they feed. Once the beetle has entered the tree the insecticides do not work.
Right now the focus is on preventing local outbreaks. To do this, the Forest Service is removing some of the trees in areas not yet infected in hopes of limiting the amount of food the beetles can access. This is called salvage and sanitation cutting.
Sudden Oak Death is also causing trouble with the Forest Service in terms of control. Only one chemical treatment, Agri-Fos, is approved for use, and only as a preventative on healthy trees. It is difficult to determine which trees to treat also, as the fungus causing the death tends to jump around.
Currently the most effective method of slowing its progress is to cut down any infected trees and then to place herbicide on the trunks. This stops the tree or shrub from regrowing from the roots. Unfortunately, the spores of this fungus can live in leaves on the ground, so even after the trees are removed it can still spread.
What you can do
Tell everyone trees are in trouble
Unfortunately, the pathogens that I have discussed are not the only ones endangering our nation’s trees. There almost seem to be too many to count.
Other invasive pests endangering our trees:
- Goldspotted Oak Borer on oak trees
- Polyphagous Shot Hole Borer on maples, oaks, cottonwood and alder
- Pitch Canker and Deodar Weevil on douglas fir and pines
- Gypsy moth on all hardwood trees
- Black Turpentine Beetle on pine trees
- Asian Ambrosia Beetle on elm, pecan, peach, oak and sweetgum
- Spotted Lanternfly on hardwood trees
- Beech Bark Disease on beech trees
- Dogwood Anthracnose on dogwoods
- European Larch Canker on American larches
- White Pine Blister Rust on eastern and western white pines
These are just a small sample of the known ones. There also is the potential for new diseases and insects to be accidentally imported from overseas with each packing crate delivered. The new big player in tree death may be sitting is a box in a port right now.
The loss of trees does not just affect those in the suburbs, or those in the city or only our parks – it affects everyone. So the next time you are talking to your friends, coworkers, or neighbors, bring up the fact that trees are dying. Talk about trees near you that may need help. Let them know the value of these trees.
The more who know, the more who care.Tell everyone you know trees are in trouble. Click To Tweet
Help find the surviving trees
Finding trees that are winning the fight against these attacks is key in saving species. We need people looking for surviving trees.
First, become familiar with identifying trees. It’s easy and fun to learn how to tell trees apart by leaves. You can buy a tree identification book, take a class at a local park or follow the guides listed below. Just get out there, walk around, and look for trees (it’s also good for your heart!)
Once you find a chestnut or elm tree, send a sample to the right place (see below). Experts will review what you sent and if it is what they need, they will visit the tree you found!
Stop buying exotic species
Most plants that you buy at a store are not native to this country. Because of this there is a greater potential to introduce harmful plants, insects and fungus into our country. When you purchase a non-native plant at a store, you are telling the nursery industry to grow more non-native plants. They respond by bringing new species from other countries, increasing the risk to our ecosystem.
The best way to combat this is to only buy native plants. Luckily many retailers are now marking plants as native on the tags making this easier. But if they haven’t marked the plant, please take the time to use your smartphone and google the name of the plant. The few minutes this takes to check before you purchase can send a huge message to the nursery industry that we want native plants.The best way to combat invasive species it to only buy native plants. Click To Tweet
Buy local nursery plants
As we have seen with Sudden Oak death, a pathogen can easily travel across the country on plants for sale.
Plant nurseries are the perfect breeding grounds for tree killers. Many of pathogens that kill trees like the warm, moist environment provided by the greenhouses. Also, plants are close together in these areas, making it easy to spread.
If you also include a greenhouse that is not disinfecting pots between uses, using unpasteurized soil or has poor sanitation, the potential for infection grows.
To prevent this you can buy your native plants from a local source. Buying locally helps prevent the spread of disease and helps the economy in your area. Finding local growers is as easy as a google search. If you are having trouble start by searching for “native plant nursery (your city or state). That simple search should get you on the right path to finding native plants near you.
Don’t move firewood
Not moving firewood is easiest and one of the most important ways that anyone can help fight these tree pests. Don’t give them a ride.
It is not enough to just look at firewood to see if it is infected. Many of these pests cannot be seen with your eye.
Even if you live in an area that you think doesn’t have any problems, still don’t move wood. There may be an unknown tree killer in your yard! Save trees and buy firewood where you will burn it.
To help with this, there is a smartphone application called Firewood Scout. This allows you to use your phone to easily find local sources of firewood. When you buy firewood, ask the seller where it came from. Sometimes firewood is brought in from far away. If this is the case, buy from someone else.
Also, when you have yard work done by a company, don’t let the company remove wood and plant clippings. This may seem like a small inconvenience but you can use this opportunity to create a compost pile, or a brush pile for wildlife. Another option is to ask the company to chip the wood into mulch and use it on your flower beds.
If you have moved firewood or tree clippings it is still not too late. It is recommended that you burn it quickly. Be sure that it is completely burned down to the ashes and that you get all leaves or branches too.
If you don’t know your state’s rules about firewood, this link will help.
Check your trees
Residents are key in helping stop the spread of these pests. In regards to the Asian Longhorn Beetle the best time to check your trees is in August. The beetles leave the trees at this time so they are easy to spot as they will be flying or crawling around.
What should you look for?
- A beetle with long antennae that are black and white
- Shiny black body with white spots just over an inch long
- Round holes in tree trunks the size of a dime or smaller
- Sawdust on the ground around a tree
- Trees that look healthy but with limbs dying
If you have a pool you are also in a great position to help look for the beetle. In August check your filters and skimmers for the beetle.
If you see these insects, report it. The USDA would like pictures of the tree damage, of the beetle or the beetle itself. If you catch a beetle, place it in a container and freeze it. Call 1-866-702-9938.
Plant for diversity and birds
Planting many different types of native trees and shrubs is an important part to stopping these tree killers. Why?
Diversity in planting is important. Try to avoid planting only a few types of trees or shrubs. For example, instead of lining a driveway with 3 maples, plant a maple, an oak and a sweetgum. Each tree will attract different types of wildlife. Diversity in plantings attracts more predators into an area because they will have more things to eat. These predators may be beneficial insects (preying mantids, wheel bugs or ladybugs) or insect eating birds (woodpeckers, flycatchers and songbirds).
Back to our 3 tree example. The maple will attract chickadees, who like to nest in them and 70% of their diet is insects. The oak attracts woodpeckers who enjoy the acorns. Woodpeckers can remove beetles from inside trees. The sweetgum tree is the host plant for the Regal Moth, whose caterpillars are eaten by preying mantids. Praying mantids also eat many other types of insects. All of these predators can help eat the very insects that are killing trees. The more wildlife that eat these pests, the less impact they will have.
Planting with diversity in mind will also slow the spread of tree killers. By spacing out trees of the same type it takes these diseases and insects longer to spread. The longer they take, the more likely it will be that a cure/preventative will be found. Or, they may miss your trees all together!
Having different types of plants in your backyard also prevents you from losing all your trees at one time. Say you have 3 trees. If a beetle kills ash trees and you have 3 ash trees, all your trees are dead. But if the beetle kills ash and you only have 1 ash, then your other two trees are still fine. Those two remaining trees will feed wildlife, give you shade and enhance your property.
Give to the cause
Monetary donations are always needed. Sometimes you will receive seeds or have a tree planted in your honor when you give. Every little bit helps! (Below are sites claiming to be saving our trees, I have not verified their claims. Donation is at your own risk).
As the future unfolds as if we want trees lining our streets, backyard shade, New England’s autumn colors or food for birds we all need to be aware of theses pests. If everyone does their part by preventing the spread of these diseases, stopping new ones from getting here and supporting those fighting them we will have a good chance of enjoying our favorite trees.
What are you going to do to help our trees? Tell me in the comments.