To spray or not to spray: that’s a question many Anchorage-area residents have wrestled with, when deciding how to protect the spruce trees in their yards from spruce bark beetles. Dousing spruce trees with an insecticide—nowadays carbaryl is the chemical of choice—has proven to be the most effective way to repel “mass attacks” of beetles.
For some, it’s a no-brainer. If carbaryl can be legally applied and is widely used on agricultural crops, lawns, and trees, then yes, by all means, spray it on the trees.
For others of us, it’s not so simple. Our government (from local to federal) allows many poisons to be used that are known to have harmful impacts to “non-target” species, including humans. We hesitate to put any toxins into lands, waters, or the air.
Jessie Moan, an Anchorage-based integrated pest management (IPM) specialist with the University of Alaska’s Cooperative Extension Service, is frequently asked, “What should I do to protect my spruce trees?” during a bark beetle outbreak like we’re experiencing now.
Moan lists pesticides among the options and explains that it’s the one tool that comes closest to 100 percent protection. (I should also mention that besides spraying carbaryl on spruce trees, an injectable pesticide is being locally tested for its effectiveness against Alaska’s bark beetle mass attacks. “While more attractive because it’s a closed system [within the tree], it takes more than a year to fully protect trees,” Moan says, adding that it’s a more expensive option.)
While pesticides offer the great likelihood of success, Moan emphasizes, “It’s a very personal choice. Spraying is not the right answer for every tree, every situation, or every person; there are so many factors that can influence that decision. I’m happy to discuss the pros and cons and tend to let that be driven by the questions people ask. My job is to make sure that people have all the necessary information to make an informed decision and I’ll tell people ‘Here are things to consider when making your decision,’ but I won’t give my opinion. I need to be neutral.”
I, however, do not.
As noted in Part 1 of this series, I once applied carbaryl—which was described to me as a “mild toxin,” something that strikes me as oxymoronic—to some spruce trees while living on Anchorage’s Hillside during the 1990s spruce bark beetle outbreak. I had misgivings even then, but wanted to save at least a few trees near the house (we lost dozens more to the beetles).
Over the years I have become even more reluctant to use “chemical solutions.” This time around, I decided to seek more natural alternatives to carbaryl, focusing on the one that Jessie puts at the top of her “good practices” list of non-toxic alternatives: I’ve regularly watered my spruce trees’ roots during Anchorage’s record-setting summer of extreme drought.
I’m hardly alone in my aversion to pesticides (or other poisons). Locally vocal opponents have included Anchorage gardening columnist Jeff Lowenfels; and Pam Miller, senior scientist and executive director of the Alaska Community Action on Toxics (ACAT).
I’ve been encouraged by Jeff’s outspoken stance against carbaryl spraying and clipped his April 24 ADN column, headlined “I’m not spraying for spruce beetles. I wish you wouldn’t either.”
As Jeff notes in that column, “The insecticides applicable are not selective. And they drift, unnoticed, into other yards and into our lakes and streams. They contain label warnings against exposure to people, pets, and wildlife as well as other insects. Even the professional biologist must implicitly agree their use is not good, which must be why blanket applications is discouraged.”
Miller and ACAT have put together a carbaryl fact sheet that summarizes many of the dangers. The handout explains, “Carbaryl targets the nervous system of insects. It disrupts the normal function of enzymes in organisms and causes neurological dysfunction that is fatal in target and a range of non-target organisms [my emphasis].”
Among its impacts, the ACAT fact sheet lists these:
— Carbaryl is highly toxic to pollinators, especially honeybees.
— There is no minimum safe level of carbaryl exposure in animal testing, particularly for developing organisms. This has ramifications for the health of human babies and children . . . EPA classifies carbaryl as “likely to cause cancer.” In studies of birds and mammals, low dose exposures over time were associated with decreases in the number of eggs and survival of young, respectively.
— Carbaryl is highly toxic to aquatic and marine invertebrates . . . Low levels of exposure can disrupt the hormone systems in fish. The main breakdown product of carbaryl is directly and highly toxic to some fish. Carbaryl can have cascade effects within the watershed where it is applied.
— Carbaryl is now widely found in drinking water sources, frequently at levels well above safe consumptive guidelines.
It’s also noteworthy that two of the strongest advocates for the herbicide control of mayday trees in Anchorage (a story for another time) told me they consider carbaryl sufficiently toxic that they would never have it sprayed onto their trees.
When talking with Miller about carbaryl, I asked if she’d consider using it to protect the spruce trees that mean the most to her, in her own yard. Her reply: “I wouldn’t use it. I’d try every alternative to pesticides, knowing that it might not be enough. I’d sadly give up my trees, rather than use carbaryl.”
That’s the thing about more benign strategies: they’ve proven less successful in protecting spruce trees during bark beetle outbreaks. As Jessie Moan told me, “Even if you’re loving your trees, giving them all the care you can, it might not be enough during a mass attack.”
Case in point: despite my regular soaking of the trees’ roots this summer, beetles have entered the three mature spruces in my yard. One spruce has already gone brown from top to bottom; the others remain green but may not survive.
Besides watering, here are other actions to consider, provided by ACAT:
Organic fertilizers; mulching of leaves; applying “ectomycorrhizal fungi” or fungal inoculants to enhance the nutrient uptake of the trees; removal of dead or dying parts of trees; pruning of lower branches to increase air circulation and overall tree health (but never do such pruning during the beetle flight season, May through July); as much as possible, maintain or enhance the biodiversity around your trees; consider purchasing and applying anti-aggregation pheromones, which reportedly are “moderately successful” in keeping beetles away from spruce trees (I especially wish I’d known about that alternative before my trees were harmed).
To learn more about such alternatives, or to get a copy of ACAT’s carbaryl fact sheet, contact the group at 222-7714 or email@example.com. To talk with IPM specialist Jessie Moan, call 786-6309.
I’d like to emphasize another important point, one that Jeff Lowenfels discussed in his April column. I greatly appreciate that Jeff, in his words, has “dedicated the later years of my life to getting the world to stop using these kinds of chemicals. If I am going to be honest with myself and you, why should the size of the organism, or its placement preventing my neighbor from seeing me, make a difference? The harm to pets, wildlife, and beneficial insects is the same no matter how big the plant we are trying to protect.”
I too have thought hard and long about such notions. It’s easy to feel affection, even love, for the large, mature spruce trees that grace our yards. In many instances they have become part of our lives, perhaps even part of our extended families. And it’s easy to overlook, ignore, or even dismiss the much smaller living creatures that move around us (unless, perhaps, they happen to be birds or bees or butterflies or maybe dragonflies). And yet in protecting our big, beautiful spruce trees with toxic chemicals, we may do great harm to the larger community of beings that also inhabit our yards, or the lands and waters—and the air—beyond them.
As I mentioned in the opening column of this series, I am deeply saddened to see the browning of spruce trees, not only in my yard, but around my neighborhood (and beyond). But I’ve decided to consider the greater good of the many, smaller forms of life that carbaryl and other chemical pesticides would kill.
As Jessie Moan has commented, “There is no easy answer.”
I’ve chosen the path that’s right for me. And I hope that others will at least seriously consider the impacts of their actions, beyond simply the spruce trees and beetles.
One more thing: I have not given up hope that one or even two of the yard’s spruce trees will survive. I continue to water them faithfully and visualize their healing. And I pray for a miracle of some kind.
Anchorage nature writer Bill Sherwonit is a widely published essayist and the author of more than a dozen books, including “Living with Wildness: An Alaskan Odyssey” and “Animal Stories: Encounters with Alaska’s Wildlife.” Readers wishing to send comments or questions directly to Bill may do so at firstname.lastname@example.org.