Metal toxicity in trees? Borer Infestation. Is it too late to save this tree? - Ask Extension
Hi,
I've just moved in to a house in Timonium and have gotten a few quotes for tree trimming and other big backyard projects. All 3 of the tree se...
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Metal toxicity in trees? Borer Infestation. Is it too late to save this tree? #941800
Asked August 07, 2026, 11:22 AM EDT
Hi,
I've just moved in to a house in Timonium and have gotten a few quotes for tree trimming and other big backyard projects. All 3 of the tree service owners(all licensed tree experts of course) referred me to Scientific Plant Services for treating a borer infestation in a very large (white?) pine tree. In addition to browning leaves, there's white sap and sawdust visible on the ground below the tree. SPS sent someone out who gave an initial assessment that they would likely be able to treat it successfully with a systemic spray(they spray up to 20 ft high I believe), but wanted to come back with their on-staff LTE. That person told me that metal is killing the tree(from some previous owner using nails, fasteners, a treehouse or something like that. There's no visible metal) and that exterminating the borers would not keep it from dying, so he recommends removal.
I did my best to research this online and found some support for this position but also a lot against it. A community of arborists on reddit chimed in uniformly against the idea that metal kills trees, and the trimmer I plan to hire is also confidently in that camp. Now I have to try to guess whether this is an old fashioned wive's tale and treat the tree anyway, or trust SPS's assessment and hire someone for a very costly tree removal. I'm hoping that folks at UMD extension would have the most accurate and up-to-date information and be able to enlighten me on metal toxicity in trees. In addition, the first SPS employee really dragged his feet on getting in touch to schedule our first appointment as well as respond with a quote, and I believe the tree has gotten visibly worse in these last 2 weeks, so I worry that it could be too late for borer treatment. I've attached a few pictures taken today and would be very grateful for an opinion on the current prognosis of this tree.
Thanks very much!
Baltimore County Maryland
Expert Response
Regardless of the initial cause of symptoms (likely environmental stress like drought before the borers arrived), the tree's current state doesn't appear to be very salvageable. Once conifers like pines lose needles for reasons other than natural senescence as the branch wood ages, they do not grow them back. That means that, even if the damage could be stopped from worsening, any growth the tree has had desiccate or otherwise die off and brown will not fill back in as the tree recovers. To be fair, the unintentional delay between first noticing borer signs and the tree's current worsened state isn't something that cost you an opportunity to intervene, as borers are typically not treatable with insecticide (in any way that reverses their damage) once they are too embedded in the tree. Even if they are treatable, nothing can make the tree able to regrow lost tissues.
Usually, borers that attack trees are drawn to individuals that have been stressed, even if symptoms of that stress are not evident yet. Typical stressors include overly-wet soil or poor drainage, drought, soil compaction or soil salt buildup (salts can come from fertilizer as well as ice melt), and air pollution and high heat. In this situation, drought is a likely contributor, especially since Eastern White Pine is not very drought-tolerant and often declines after a few decades of accumulated suburban or urban stresses, and since most of Maryland has been in a notable drought for the past two years. The excessively wet year of 2018 (and to a lesser extent, 2019) also could have killed or weakened some of the tree's roots, and a compromised root system that hasn't fully recovered yet would be in an even worse position going into a period of drought. This is conjecture with regards to this specific tree, but it is a set of conditions that has stressed and contributed to decline in other trees around our region, including deciduous species like oaks.
Some wood-boring beetles introduce a fungus to the wood as they tunnel, so even if the borers could be killed with pesticide treatments, the fungus cannot. (You can learn more about common conifer beetle borers on the linked page.) Sometimes it's the tree's own reaction to invasion that causes dieback, a bit like an over-reactive immune response in a person with certain infections. In the tree's case, the resin produced or other methods of blocking insect/fungus spread in the sapwood actually clogs the tissues and reduces how much moisture or nutrients can reach the canopy, and there is no remedy for that. Not all borers consume cambium (the vital living tissue just under the bark) -- some tunnel into heartwood, which is inner trunk wood that is comprised of already-dead tissues. Which borer is present will dictate where it's feeding, and therefore what kind of damage it's doing.
We are not aware of research regarding metal exposure causing dieback or killing trees by itself. Of greater risk in that situation would be the physical injury itself to the trunk and sapwood (which lies just under the bark) if any metal objects were drilled or nailed into the trunk. Not only is that immediate damage to important tissues, but the wound can serve as a point of entry for wood decay or infection. If the inspector can't point out examples of visible metal in the tree's wood, though, that calls into question why they think that's a factor here. Embedded objects can make grinding a tree that's cut down risky, since the metal could damage the grinding equipment or become hazardous shrapnel in the process. Therefore, if someone did see evidence of embedded metal, it's important that's brought to the attention of a tree removal service whenever the tree needs to be taken down.
Metal in the soil is another matter, and many soils likely have some degree of metallic elements in them (whether naturally-occurring or from pollution) that do not negatively or measurably affect plants. In fact, some plant nutrients (like magnesium and manganese) are metals, although the plant absorbs them in various chemical forms. The person should be able to demonstrate lab-measured soil metal levels (and specify which metals in particular they think are involved), though, to make such a claim that it's killing a tree. White Pine are sensitive to pollutants in general, but that claim implicating metals sounds extraordinary and we'd think the burden of proof would be on the person who suggested it.
Overall, there are a wide variety of factors that can directly cause (or contribute to cumulatively) a tree's decline and death. Often it arises from root health problems or soil conditions that stress roots first, well before any canopy changes appear. Based on the pine tree's current state, in our opinion, it unfortunately looks unsalvageable (or at least not worth the expense of treating it when that won't significantly improve its appearance) and probably should be taken down.
Miri
Usually, borers that attack trees are drawn to individuals that have been stressed, even if symptoms of that stress are not evident yet. Typical stressors include overly-wet soil or poor drainage, drought, soil compaction or soil salt buildup (salts can come from fertilizer as well as ice melt), and air pollution and high heat. In this situation, drought is a likely contributor, especially since Eastern White Pine is not very drought-tolerant and often declines after a few decades of accumulated suburban or urban stresses, and since most of Maryland has been in a notable drought for the past two years. The excessively wet year of 2018 (and to a lesser extent, 2019) also could have killed or weakened some of the tree's roots, and a compromised root system that hasn't fully recovered yet would be in an even worse position going into a period of drought. This is conjecture with regards to this specific tree, but it is a set of conditions that has stressed and contributed to decline in other trees around our region, including deciduous species like oaks.
Some wood-boring beetles introduce a fungus to the wood as they tunnel, so even if the borers could be killed with pesticide treatments, the fungus cannot. (You can learn more about common conifer beetle borers on the linked page.) Sometimes it's the tree's own reaction to invasion that causes dieback, a bit like an over-reactive immune response in a person with certain infections. In the tree's case, the resin produced or other methods of blocking insect/fungus spread in the sapwood actually clogs the tissues and reduces how much moisture or nutrients can reach the canopy, and there is no remedy for that. Not all borers consume cambium (the vital living tissue just under the bark) -- some tunnel into heartwood, which is inner trunk wood that is comprised of already-dead tissues. Which borer is present will dictate where it's feeding, and therefore what kind of damage it's doing.
We are not aware of research regarding metal exposure causing dieback or killing trees by itself. Of greater risk in that situation would be the physical injury itself to the trunk and sapwood (which lies just under the bark) if any metal objects were drilled or nailed into the trunk. Not only is that immediate damage to important tissues, but the wound can serve as a point of entry for wood decay or infection. If the inspector can't point out examples of visible metal in the tree's wood, though, that calls into question why they think that's a factor here. Embedded objects can make grinding a tree that's cut down risky, since the metal could damage the grinding equipment or become hazardous shrapnel in the process. Therefore, if someone did see evidence of embedded metal, it's important that's brought to the attention of a tree removal service whenever the tree needs to be taken down.
Metal in the soil is another matter, and many soils likely have some degree of metallic elements in them (whether naturally-occurring or from pollution) that do not negatively or measurably affect plants. In fact, some plant nutrients (like magnesium and manganese) are metals, although the plant absorbs them in various chemical forms. The person should be able to demonstrate lab-measured soil metal levels (and specify which metals in particular they think are involved), though, to make such a claim that it's killing a tree. White Pine are sensitive to pollutants in general, but that claim implicating metals sounds extraordinary and we'd think the burden of proof would be on the person who suggested it.
Overall, there are a wide variety of factors that can directly cause (or contribute to cumulatively) a tree's decline and death. Often it arises from root health problems or soil conditions that stress roots first, well before any canopy changes appear. Based on the pine tree's current state, in our opinion, it unfortunately looks unsalvageable (or at least not worth the expense of treating it when that won't significantly improve its appearance) and probably should be taken down.
Miri
