Posts Tagged Redbay Ambrosia Beetle
As promised in my previous post, this is my summary of the presentations given on the second day of the virtual conference of the NC Invasive Plant Council this past week. I apologize for the length. I tried to be as succinct as possible.
That was the title of the talk, just the generic name of the herbicide better known to many by the commercial product with the name that rhymes with groundup. This presentation was given by a professor from NC State University. Although it is much more than a land-grant institution concerned with agriculture and engineering today, those areas were its original focus, and are still very important. Much academic effort remains focused on supporting what I think of as the traditional agriculture and horticulture industries. I assume it is that focus that explains the approach taken by this speaker. I feel obliged to go into some detail about this presentation. I think my reasons will become evident quickly.
From my perspective as a well-educated woman with a substantial knowledge of ecology and gardening, his talk began inauspiciously. His opening slide portrayed a woman dressed in the 1950’s cliché style of a “typical housewife” – perfect dress, high heels, permed hair, and make-up. She was standing on an immaculate green lawn in front of a house. Behind her, she pulled a large clunky-looking machine that was spraying what I assume was supposed to be an herbicide mixture onto her lawn, all while smiling prettily for the camera.
I pondered what message the speaker intended to convey with this image. Was he harkening back to “the good old days” when women knew their place and happily spread poisons without worrying about safety protocols? Did he think he was being funny? I tried to continue listening with an open mind, but the talk went downhill from there for me.
This professor was not the most coherent of speakers, but I think his primary point was that anyone worried about glyphosate is misinformed and should shut up and leave the poisons to the “experts.” He showed a few graphs demonstrating how much less toxic glyphosate is than some of the herbicides farmers used in the recent past. That’s true. Glyphosate doesn’t persist in the environment as long as those more toxic herbicides, and it is probably less dangerous to humans.
His next words raised my hackles. He showed the label from the Non-GMO Project that appears on food products that have been certified by that organization. At the same time, he said, “Not to be sexist or anything, but women buy most of the food in the house.” I braced myself. As best as I could make out, his point was that women are so stupid that we think the Non-GMO Project label means the food was produced without the use of herbicides and that makes the food safer, which is why we buy it. I can’t speak for women everywhere, but I can tell you that I – a woman for some decades now – know the Non-GMO Project label certifies that the food was not created by bioengineering methods that genetically modified it.
The speaker never really articulated his objection to the Non-GMO label, but I can guess what it might be. Traditional agricultural operations that produce hundreds of acres of soybeans, corn, and other staple crops have been moving substantially toward the use of genetically modified seeds that contain genes making the food crops resistant to the application of glyphosate. Now, instead of needing to till crop rows to control weeds, farmers merely spray their entire fields with glyphosate, thus killing all the weeds while the food crop survives.
I imagine that my readers can come up with all kinds of reasons for being uncomfortable with the idea that food they might eat is grown this way. Personally, I’ve been grateful for the Non-GMO product certification label since it began appearing. And I’ve always known that the label does not necessarily imply that the food was grown organically and/or without the use of herbicides/pesticides. It merely indicates the food was not bioengineered so that poisons could kill weeds in the field without killing the crop.
After insulting female food-buyers everywhere for being stupid enough to conflate non-GMO foods with those grown organically, the speaker spoke at length about the fact that no government agency has declared that glyphosate causes cancer in humans or other mammals. He made a point of stating it that way for good reason. Scientists have been studying the effects of glyphosate on non-mammals for quite some time. Here are a few relevant journal articles:
- Glyphosate inhibits melanization and increases susceptibility to infection in insects
- Common weed killer – believed harmless to animals – may be harming bees worldwide: Glyphosate appears to alter the bacteria in the insect’s guts, making them more vulnerable to infection
- Effects of the Herbicide Glyphosate on Honey Bee Sensory and Cognitive Abilities: Individual Impairments with Implications for the Hive
- Amphibians Are Not Ready for Roundup
- Chronic exposure to a glyphosate-based herbicide makes toad larvae more toxic
For those who think I’m cherry-picking journal articles, here’s one for the pro-glyphosate team:
I am not an expert on herbicides, but it appears to me that the most generous statement one can make is that, at best, data are mixed on the impacts of glyphosate on non-mammalian wildlife. I suspect that, as the last article above states, when used correctly at appropriate concentrations and appropriate application techniques, glyphosate is a useful tool in the battle to control non-native invasive plants. If the presenter of this talk had said this, instead of “mansplaining” to women he deems too stupid to understand, I would not be writing all this. However, because this professor’s job is to support the agriculture industry’s use of glyphosate, I think he chose to obfuscate with a tirade about non-GMO labeling on food products. Moving on…
Response of Invasive Plants to Fire at Picture Creek Diabase Barrens
After the previous talk, it was a great relief to me when this presenter began. A plant ecologist, she is the Program Manager for the North Carolina Department of Agriculture’s Plant Conservation Program, a group whose mission is to protect rare plants in North Carolina.
Picture Creek Diabase Barrens is a site containing a remnant community of Piedmont prairie plants. Hanging on by the merest of threads, it survived because it grows beneath high-tension powerlines, which means the power company has been keeping that area free of forest encroachment for decades. Until fairly recent times, the trees were removed manually, which is probably why the rare plants survived. These days, of course, utility companies prefer to spray herbicides on such lines. In my area, they do it using helicopters. Many areas deploy teams of workers with backpacks full of herbicide to kill everything growing within the utility right-of-way.
Conservation groups, including the NC Botanical Garden and the Friends of Plant Conservation have been helping to restore this particular rare ecosystem. In addition to tackling the non-native invasive plants encroaching on the area, they’ve collected seed from some of the rare plants, which they grew out and then planted on the site. Controlled burns are very effective at controlling unwelcome plant species in Piedmont prairies. It was the way they were maintained by Native Americans before European colonists arrived. Burns don’t always control all unwanted species. Careful applications of correct concentrations of glyphosate are also used to battle invasive species on this site. The presenter emphasized the need for careful applications. Her staff is trained to recognize desirable and undesirable species. It is slow, painstaking work to move through this fragile plant community spraying herbicide only on unwelcome species.
The speaker emphasized this because of unhappy experiences with crews from the power company that are paid to spray herbicides on the powerline right-of-way. They are not trained to recognize one plant from another. They douse anything green with poison, and they move quickly, which may explain how they missed the signs marking this protected rare plant community as a no-spray zone. The speaker told us it has taken years of hard work to persuade the power company to allow conservation experts to manage rare plants beneath powerlines. After a recent incident in which power company contractors missed the signs and sprayed herbicide on the protected rare plants in this location, the speaker told us all parties sat down together again to discuss how they might prevent this from happening in the future. The good news is that they all agreed to meet together once per year for the indefinite future to ensure that all parties are always current on agreed-upon procedures, thereby decreasing the likelihood of future communication lapses.
Invasive Plants in Glades
The man who presented this talk is a Public Lands Field Biologist for MountainTrue, a conservation organization that “champions resilient forests, clean waters, and healthy communities in the Southern Blue Ridge.” I would describe his interesting slide presentation as, at best, tangentially related to the subject of non-native invasive plants. He spent almost all of his time describing the interesting, often rare plants that occur in glade plant communities. His definition of what constituted a glade was a tad fuzzy to me, but suffice it to say these communities grow on the sides of mountains on relatively steep slopes. He mostly showed us many photos of interesting plants. At the end of his talk, he mentioned the non-native invasive plants that he usually sees encroaching on glade communities. I don’t remember if he talked about how he controlled them.
Emerald Ash Borer and Other Invasive Pests
As far as I’m concerned, this was the most depressing presentation of the conference. The speaker, a Ph.D. entomologist for a local big tree-care company, described the non-native invasive insect species that he believes will impact our local ecosystems most significantly. I’ve written several times about one of them. I may have mentioned the second invader at least once, and I don’t think I’ve described the other one before.
I’ve written about this phenomenally destructive insect several times in this blog. Enter “Emerald Ash Borer” in the search box to find those entries. I also wrote an article about it for the magazine of the NC Botanical Garden.
This insect from Asia is systematically killing every ash tree in North America. In northern states like Michigan, the only ash trees still alive are the ones treated every other year with systemic insecticide. The insecticide is injected into the tree, the poison permeates the entire tree, and any insect that takes a bite of a treated tree dies. Federal agencies are experimentally releasing four different species of parasitic wasps from Asia that target varying life cycle stages of EAB. The speaker said that at least one of those wasp species was found the following year, meaning it successfully reproduced by feeding EABs to its larvae. This potentially good news is not great news. First, these releases are still experimental. Regular folks and even tree companies, such as this speaker’s employer, do not have access to these wasps. Also, the speaker noted, no one believes these wasps can eradicate EAB. At best, if the wasps successfully multiply, it might be possible – maybe – for the wasp and EAB populations to reach a sort of truce that might allow some ash trees to survive. Maybe.
A lot of us were hoping, I think, that the wave of marauding EABs would pass through an area, then leave after killing all the ash trees. Alas, according to this speaker, that is not what is happening. Up north, where EAB has been present for 20 years, he saw instances in which a homeowner decided it was safe to stop treating the ash tree on their property, because all untreated ash trees were dead. In such cases, EAB infestations killed such trees five years after insecticide treatments were stopped.
The speaker told us that it is hard to tell when EABs have infested an ash tree, because they begin by boring into branches at the top of the tree, where it is hard to see the dieback. By the time most folks notice their ash trees are unwell, EAB infestation is too far along for systemic insecticide treatments to be effective. He said that if more than 30% of the branches in the canopy are dead, the tree is doomed. He also said that he has seen ash saplings with trunks the diameter of his thumb infested with EAB, which is how the invader persists in an area indefinitely. The species also enjoys dining on our native fringe trees. Barring a miracle, I think it is safe to assume North American ash forests are doomed.
He also mentioned one other fact about dead ash trees that I did not know. When dead, this species becomes dangerously brittle very quickly. He told us that any “tree expert” who claims he can climb your dead ash tree to cut it down from the top is risking his life. No sane arborist, he said, will ever climb a dead ash tree, because it can break and send him tumbling in an instant. Either the tree must be felled in its entirety by cutting it at its base, or a bucket truck must be used to safely access the top of the tree to remove branches.
When the non-native Redbay Ambrosia Beetle lays its eggs inside plants in the laurel family (Lauraceae), it also injects a fungus, called Laurel Wilt, that kills the tree within months. Redbay (Persea borbonia) is a dominant member of plant communities growing in the southeastern coastal plain. In North Carolina, when you drive past areas where this species once dominated, you see miles and miles of dead trees.
Redbay Ambrosia beetles also kill spicebushes (Lindera spp.) and sassafras trees in the Southeastern US. Somehow the beetle has made it to California, where it is posing a grave threat to avocado groves and native California bay laurel trees. The speaker told us that female Redbay Ambrosia beetles are parthenogenic, which means they lay fertile eggs without the need for insemination by a male. One female beetle, the speaker told us, can kill a tree simply by laying her eggs in it.
The speaker joked about the beetle as a grave threat to guacamole lovers everywhere. I’m more worried about Spicebush and Palamedes Swallowtail butterflies. Their caterpillars dine exclusively on plants in the Lauraceae family. And think of the native fruit-eating birds that rely on the fruits of redbay, spicebush, and sassafras. What will they eat when all these species are dead? He also mentioned that the latest data show this insect has been detected in a county less than a hundred miles from mine. It is moving inland from the coast, no doubt on the lookout for spicebushes and sassafras trees.
I warned you this speaker’s talk depressed me.
Study the pictures in the link above to learn what this insect looks like. If you see it, report it to your local extension agent. The speaker said this insect is not quite in NC yet, but is expected any time now. This is not good news.
Larvae of this insect happily eat and damage many different species, including fruit trees. According to the expert, this insect may not kill trees outright, merely damage them. Being from Asia, they evolved with Tree of Heaven (Ailanthus altissima). This Asian invasive tree has invaded North Carolina forests and roadsides and is a favorite food of Spotted Lanternfly – just another example of why non-native invasive plants are not our friends.
The speaker showed a short, truly creepy video of thousands of larvae of Spotted Lanternfly swarming up the trunk of a fruit tree, covering every inch of it. It reminded me of videos of fire ants swarming over an animal. Scary stuff.
The entomologist said the larvae damage but do not usually outright kill trees. However, they do kill vines, and the larvae love to eat vines, especially grape vines. The speaker says he’s even seen this insect kill poison ivy vines. I wanted to ask him if he knew whether it would eat Asian wisteria or kudzu – two Asian invasive vines I’d love to see disappear, but the virtual format of the meeting and a tight timeframe did not give me that opportunity.
I am assuming that the insects kill vines, because vines are smaller. The larvae literally drain them dry. He emphasized that the wine industry is terrified of this insect, because of its fondness for grape vines. He said that Spotted Lanternfly has been sighted in western Virginia along its border with NC, just above NC’s Yadkin river basin – a region acclaimed for its wineries.
Breaking News Regarding NC’s Spotted Lanternfly Situation!
A Master Gardener friend, just pointed me to this article. The NC Dept. of Agriculture and Consumer Services Plant Industry Division has recruited two canines to aid in detecting this insect, which the experts suspect may have already begun infiltrating the state. Here’s hoping their excellent noses can find early infestations that their human coworkers can eliminate!
I hope my posts about this conference have been helpful. When the NC-IPC makes videos of the presentations available on their web site, I’ll note that in this blog, so that you can view them yourself and draw your own conclusions.
When I wrote about Sweet Bay here, I mentioned that it is one of three so-called bay species native to southeastern coastal plains. Redbay (Persea borbonia) is another of those bay species. Like Sweet Bay, Redbay’s leaves are evergreen and it is a usually a smaller tree (20-30 feet), although it can grow taller. Also like Sweet Bay, the leaves of this member of the laurel family are pleasantly fragrant — actually more than those of Sweet Bay. It was consequently used as a bay leaf herb substitute by European settlers of the region.
Unlike Sweet Bay, the flowers of Redbay are relatively inconspicuous. Its fruits are purple berry-like drupes that many native birds find tasty. The birds, of course, eat many kinds of berries, but there’s a lovely butterfly whose larvae rely nearly exclusively on this tree: the Palamedes Swallowtail. Its caterpillars may also dine a bit on sassafras (Sassafras albidum), another member of the laurel family, but this small tree is much less abundant on the coastal plain than Redbay. The Palamedes Swallowtail is occasionally seen further inland, but Redbays are vastly more common on the coastal plain, so that’s where it tends to stay.
These two laurel-family-dependent butterflies are some of our larger, more dramatic summer garden visitors, and I fear their days may be numbered, because their larval food source is imperiled. An alien insect is marching up the southeastern coast of the United States, leaving dead stands of Redbay in its wake: the Redbay Ambrosia Beetle. This alien insect carries a deadly fungus that kills infected Redbays usually within a month of infection. The fungus invades the trees when female Redbay Ambrosia Beetles bore into stems to lay their eggs. As they chew, their infected mouth parts introduce the fungus. One month later, the tree dies. One month!
Last week, the NC Forest Service released a news bulletin warning that this beetle has now reached the southeastern-most counties of North Carolina. Scientists have not found any weapons against this invader. They expect the beetle to continue its northward march until it runs out of Redbays.
After that, they can only guess what may happen. One possible scenario is that the beetle may move to other laurel family species — sassafras and spicebush. This might well spell doom for the Spicebush Swallowtail if its larval food source is killed by the invading beetle and its fungus.
And, more important to Florida orchard growers, they fear it may jump to another member of the Persea genus — avocado. The USDA Forest Service has a big section on their Web site that describes all the issues relating to this invading insect and its killer fungus hitchhiker. Read all about it here.
One strategy suggested to preserve mature Redbays is to plant them outside their native range. The southeastern Piedmont has proven to be an excellent home for this species. In his Manual of Woody Landscape Plants, Michael Dirr notes that this native of coastal swamps is actually quite adaptable to drier upland soils, and in his opinion, the trees often look healthier than wild ones growing on the coastal plain.
My tree is about 25 feet tall, and it leans a bit, never having fully straightened after an intense, prolonged ice storm — but that can happen to any evergreen species. Mine has remained reliably evergreen even during cold winters, and our severe droughts have not hurt it. It provides a nice bit of green in my winter landscape, as well as shelter and food for birds.
After reading about the impending obliteration of coastal Redbays, I’ve decided to plant two more trees near the one I’ve already got. I am hoping that perhaps by growing three, they might have a better chance of perpetuating themselves in the landscape over the long haul. And I’m hoping that their isolation in the middle of a Piedmont forest with no other Redbays around will prevent the Redbay Ambrosia Beetle from finding them.
Perhaps if more Piedmont gardeners added this lovely, durable evergreen to their home landscapes, Redbays would have a better chance of surviving this invader and its killer fungus. I’ve decided it’s worth a try. Perhaps you might consider joining me?
You won’t find Redbays for sale in your average nursery. I’ve ordered mine from my favorite mail-order supplier of native species.