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This summer, Mountain View cut down dozens of large trees around the public library and in nearby Pioneer Park because of their poor condition. Officials have now concluded that an herbicide likely contributed to the trees’ demise, according to a city press release.
“Laboratory testing of soil and tree tissue samples from several affected locations detected varying concentrations of imazapyr, the active ingredient in an herbicide previously used by the city for weed control,” the press release said. “The city has discontinued its use and is taking steps to treat and monitor the affected soil and tree health.”
In total, Mountain View removed 33 trees that were in declining condition, including a row of sycamore trees that lined Franklin Street in front of the public library. The city plans to remove two more trees at the corner of Mercy and Franklin streets, the press release said.
However, more trees may also be on the chopping block. Another 150 trees are showing deterioration similar to the ones that were removed in July, according to the press release. The locations of those trees include Stevenson Park, Gateway Park, Castro Street roadway medians and the corner of Castro Street and Evelyn Avenue.
According to the city’s press release, while testing results confirmed the presence of imazapyr, it is not known the extent to which the herbicide contributed to the decline of the trees or whether other factors also played a role.
Mountain View began using imazapyr in 2021, after it discontinued the use of glyphosate, commonly known as Roundup, according to an update posted to the city’s website. At the time, city staff considered imazapyr a good alternative.
Mountain View has now begun a process called “soil drenching” to try and reduce the level of imazapyr in the impacted areas, according to the tree update. The soil will be tested every 90 days to monitor conditions and replacement trees will be planted once city staff determine that the affected areas are cleared of imazapyr and can support newly planted trees.
The new trees will be native species appropriate to each location based on the city’s recently adopted biodiversity and urban forest plan, the update said.
City staff are also working with local, regional and state partners to reduce pesticide use and “identify products that balance potential impacts on trees, landscaping and other vegetation,” the press release said.
There are more than 27,500 publicly maintained trees in Mountain View, according to the city.
It has been known since the 1980s that imazapyr is toxic to non-target plants including hardwood trees. And in 2006, the EPA assessed it as dangerous to use near trees. The problem is even listed on the product label! So, my question is, how is it that city staff were unaware of this? That sounds like a major screw-up.
City staff aren’t going to read labels or do any minimal research on their own, its much better to spend thousands on outside consultants to perform detailed soil analysis (after all the trees died) to come to the same result as spending 30 seconds beforehand to read a label. It’s not their money.
I’m sure its also healthy for dogs that tend to hang around trees in parks and city areas, and they track that into homes as well.
In fact, imazapyr is specifically marketed as a tree killer!
Who is making these decisions? Is anyone going to suffer a career consequence as a result of this?
Don’t understand why herbicide would ever be used in the tree wells on Franklin. Between the metal grates and the frequent dog spraying, weeds would hardly be a problem….
The label:
DO NOT use … over the root zone of trees and shrubs.
DO NOT apply to slopes as movement on the soil surface may damage desirable plants down the slope.
For shrubs and trees, DO NOT apply closer than twice the distance from the trunk to the drip line, as roots may be within this area.
Same thing happened in Ojai a couple years ago. Glyphosate is relatively harmless and is an essential ecological restoration tool. It deactivates when it touches soil particles. The physiological pathway is therefore through the leaves and stems. Imazapyr is very destructive and readily infiltrates the roots. It should never be used around native vegetation, or anything you want to survive, for that matter.
Straight from the label:
https://cdn.shopify.com/s/files/1/0014/4343/0463/files/Imazapyr_4_SL_Label_ChemicalWarehouse.pdf?4486339862731143996
“DO NOT apply or drain or flush equipment on or near sensitive desirable plants, or on areas where their roots may extend, or in locations where the chemical may be washed or moved into contact with their roots.”
“DO NOT drain or flush equipment on or near desirable trees or other plants, or on areas where their roots may extend, or in locations where the treated soil may be washed or moved into contact with their roots.”
And from the non-target plant precautions:
“Untreated trees can occasionally be affected by root uptake of this product through movement into the top soil. Injury or loss of desirable trees or other plants may result if this product is applied on or near desirable trees or other plants, on areas where their roots extend or in locations where the treated soil may be washed or moved into contact with their roots.”
It’s well known that many trees near the chamber of commerce were slated for removal to make way for more high rise development downtown. We all know how much developers appreciate heritage trees, so maybe there was some “help” provided to reduce the problem? We’ve seen this before in Mountain View…the burrowing owls in the way of development at Shoreline 30+ years ago? – Oh shucks the guy driving the tractor that discs the field didn’t know there were protected owls there so now that the owls are displaced or dead the buildings can now be built. Is that what happened to our trees? Hmm too much un-checked development in Mountain View. Please stop.
I will ask again: is anyone facing career consequences for this sloppy and destructive decision?