Thursday, March 4, 2010

Fighting Emerald Ash Borer Could Harm Birds and Bees

Posted by Kirk Mona
I learned something interesting while reading the City of St. Paul's EAB Response Management Plan. Treating trees for Emerald Ash Borer in Twin Cities could harm bird and bee populations. It all comes down to pesticide use. The city rejected allowing residents to use any pesticide they choose on publicly owned trees because of the potential environmental impact. Also, the city will only allow injection of pesticides into public trees such as those on boulevards by a trained professional and not spraying which is a good thing as far as environmental impact. Residents can treat their own trees with pesticides and the official policy of the city will be that, "City Forestry staff will provide residents available information on EAB pesticides when requested but will remain neutral on whether or not to use." The document does not makes clear what the "available information on EAB pesticides" will be. It could simply be a list that says which ones work or it could include information on the harm they can cause. The fact that they are going to remain neutral on whether or not residents should use them may indicate that they will not tell people about the harmful effects of the pesticides but perhaps I am wrong on this. The same document states that pesticide use is usually not cost effective in the long run and there are environmental risks. I hope they pass that information along to the public as what one person does in the city effects us all.

Most pesticides used to treat Emerald Ash Borer infestations contain Imidacloprid. Imidacloprid is the first pesticide in a new family of pesticides based on nicotine. Nicotine occurs in tobacco plants as a natural insecticide.

The City of St. Paul's EAB Response Management Plan, contains an Appendix A which is an Imidacloprid Fact Sheet. While they do not say where they got the information it is clearly copied directly from the Sierra Club Canada Imidacloprid Fact Sheet. They city fails for not citing their source of the fact sheet. The original can be found online and includes all of the footnotes that are missing from the city's document. [Note to St. Paul: If you are going to rip of someone's work and include it in your document and the text contains footnotes it makes you look dumb to not include the footnotes you are supposedly citing.] Of interest in the fact sheet are the following passages.

"Imidacloprid is toxic to birds and wildlife and mildly toxic to fish. Imidacloprid use has been linked to eggshell thinning in birds[3], reduced egg production and reduced hatching success at exposures of 234ppm in food.[4] It is highly toxic to certain species including the house sparrow[5], pigeon, canary and Japanese quail[6]."

As far as bees are concerned, the report says, "Imidacloprid is an insecticide, so it is not surprising that it is toxic to many beneficial insects such as honey bees to which imidacloprid is highly toxic.[7] The widespread use of imidacloprid has been linked to colony collapse disorder, a phenomenon described by beekeepers, researchers and government officials when entire hive populations seem to disappear, apparently dying out. France has put restrictions on the use of imidacloprid (GauchoT) since the 1990s over concerns for the bee population."

The link between Imidacloprid and colony collapse disorder isn't really clear but caution is warranted.

I know there are bee hives on the St. Paul campus of the U of M for the agriculture fields. Since the fields are essentially right in the hot zone for EAB infestation I wonder how much pesticide has been used in the area and if there has been any affect on the bee colonies?

My concern is that residents who are not experienced in using pesticides will use them incorrectly and in doses that are harmful to the environment in an ultimately futile effort to save ash trees in their yards. Too many homeowners take the "more is better" approach to chemicals and really don't care what labels say.



[3] U.S. EPA. Office of Pesticide Programs. 1994. Pesticide fact sheet: Imidacloprid. Washington, D.C., Mar. 18.

[4] U.S. EPA. 1992. Data evaluation record: NTN 33893 MRID No. 420553-13. Washington, D.C., Aug. 24.

[5] U.S. EPA. Office of Pesticide Programs. 1994. Pesticide fact sheet: Imidacloprid. Washington, D.C., Mar. 18.

[6] U.S. EPA. Office of prevention, Pesticides and Toxic Substances. 1994. Imidacloprid, acian 6(a) (2) submittals. Memo from A.F. Mciorowski, Ecological Effects Branch, to D. Edwards, Registration Division, Washington, D.C.

[7] .S. EPA. Office of Pesticide Programs. 1994. Pesticide fact sheet: Imidacloprid. Washington, D.C., Mar. 18.


troutbirder said...

Interesting. I hope the city has better luck on this battle than I remember it did in the the fight against Dutch Elm in my childhood, growing up on the East Side in St. Paul.

walleye said...

I understand your concern about the use of chemicals to combat EAB. However, the way imidacloprid is used to combat emerald ash borer in ash tree reduces the your enviromental concerns.
1.The treatment method for ash tree is to pour a imidacloprid solutions around the base of the tree and the product is absorbed into the soil and roots of the tree. No spraying needed reducing any exposure to off target pests.
2. Ash trees are wind pollinated so bee should not come in contact with imidacloprid in this use.
3. Imidacloprid has shown good result in controling EAB- go to and look of the homeowner pesticide uses.
4. If you compare the cost of removing your tree and replacing it protecting your tree becomes cost effective. $700-$1500 to remover your tree to $50 a year protecting it- do the math

Kirk Mona said...

Thanks for your comments Walleye. As to your first point, yes, Imidacloprid is poured around the base of the tree (or injected by professionals). As I said in the first paragraph, the city of St. Paul will not allow spraying of trees. There is still concern about imidacloprid being poured on soil as it can get into the bodies of worms which are a food source for birds like American Robins. I'll grant though that this is less of a concern than if sprays were being used.

I don't disagree that imidacloprid is effective but I think people do need to do the math on whether or not they want to save their tree. I don;t think it is as simple of an equation as you propose. Many of the Ash trees in St. Paul were planted in the 1980s after dutch elm disease wiped out the elms. While they can live to be over 100 years old the average lifespan of a green ash is 30 to 50 years. The trees planted in the 80s are middle aged. There are however, many much older ash trees in the city. Yes, treating once is cheaper than removal. $50 is approximately the cost to treat a tree with a 10 inch diameter. Many of the ash trees in St. Paul are larger than this and will cost more. My neighbor's tree, for example, is about double that size so would cost $100 per year to treat. If the tree is near time to be replaced anyhow it may make sense to remove it now rather than spend hundreds of dollars on it for a few years only to turn around and remove it anyhow. Also, if it is a substantially younger tree the homeowner must weigh the cost of starting over with a new tree versus treating the tree for many many years to come.

There certainly isn't an easy solution.