September 27, 2026
Dear Mayor Ramos and Councilmembers,
The undersigned organizations are writing to request a moratorium on herbicide use in City parks, street tree wells, medians, and other publicly maintained landscaped areas until Mountain View's Integrated Pest Management (IPM) Policy and implementation practices can be comprehensively reviewed and updated.
We appreciate that the City will be planting native species to replace removed trees. However, the appropriate response to the loss and decline of so many public trees should be more than replacing the trees and replacing one herbicide with another. The City should understand how this happened, provide full transparency, and transition away from routine herbicide use in its public landscapes.
The discovery of imazapyr in the soil and tissues of affected trees, following the decline and death of numerous mature trees, should be a wake-up call. Thirty-three trees have already been removed, approximately 150 more are showing varying degrees of decline, and imazapyr was detected in every soil and tree-tissue sample tested.
What is particularly concerning is that this happened despite the safeguards of the City's existing IPM program. City staff receive annual pesticide training, products are reviewed by a licensed Pest Control Adviser, and the program is inspected annually by the Santa Clara County Agricultural Commissioner's Office. As described in the City’s September 2026 Update on Tree Decline and Replanting, in 2021, the City determined that imazapyr met its IPM criteria with a Category III/Caution rating and was appropriate for use.
As demonstrated by the examples below, the risk to trees was suggested as early as 2006 and continued to be documented throughout the next two decades.
The EPA's 2006 review of imazapyr stated, “there are ecological risks of concern associated with the use of imazapyr for non-target terrestrial plants1... that cannot be precluded at this time.”2
In 2018, approximately 300 hardwood trees at Milwaukee County's Wehr Nature Center died following the use of imazapyr to control invasive weeds3.
In 2024, Ventura County reported that hundreds of mature trees in county parks were dead, dying, or damaged following improper applications of imazapyr4.
This raises serious questions about the City's pesticide review and approval process and highlights the need to periodically reevaluate approved pesticides as new information and evidence of harm emerge. Rather than replacing imazapyr with yet another chemical alternative, Mountain View should commit to nonchemical methods of controlling weeds.
Mountain View should follow the example of neighboring cities:
Palo Alto has 21 designated pesticide-free parks and facilities, but its practices go considerably further: pesticides and herbicides are not used in its parks and open spaces, pesticides have not been used on public trees since 20125, and herbicides are not used routinely.
In 2017, Menlo Park’s city council unanimously voted to eliminate herbicides from all city parks, following a successful pilot the year before.6
Mountain View should similarly transition away from herbicide use in parks, street tree wells, medians, and other public landscaped areas. Herbicides should be reserved for narrow circumstances involving a specific, localized ecological or public-health need when effective nonchemical methods are not available.
We therefore ask the City for the following.
Establish a temporary moratorium on herbicide use in City parks, street tree wells, medians, and other publicly maintained landscaped areas until the City's IPM Policy and implementation guidance have been updated and adopted through a transparent public process.
Narrow exceptions could be allowed for documented ecological or public-health needs when effective nonchemical methods are not practicable.
Any exception should require written justification identifying the specific need, the nonchemical alternatives considered, why those alternatives are not feasible or effective, the herbicide and amount proposed for use, and measures to protect trees and other non-target organisms.
All exceptions and applications should be transparent and publicly reported.
Develop an updated IPM Policy and detailed implementation guide through a transparent process with meaningful public input. The policy and implementation guide should address:
prioritization of nonchemical alternatives;
pesticide selection and scientific review;
protection of trees, wildlife, soil, water, and other non-target organisms;
application practices and safeguards, including requirements for City staff and contractors;
monitoring requirements following pesticide applications, including what is monitored, who is responsible, how long monitoring continues, and what actions are required when harm is identified;
clear roles, responsibilities, and oversight; and,
public reporting and accountability.
Transition to nonchemical weed-control practices. Expand the use of mulch, manual and mechanical weed control, and other nonchemical approaches, drawing on successful practices in jurisdictions that have reduced or eliminated routine herbicide use.
Strengthen the pesticide review process to include new scientific research, documented and anecdotal reports of harmful effects, and other early warning signs of harm to non-target organisms, and immediately suspend use when new evidence of potential harm emerges.
Provide full public transparency regarding pesticide use. Make publicly available the City's pesticide application records, pesticide-use reports submitted to the Santa Clara County Agricultural Commissioner's Office. Routinely report this information to the PRC and post it online.
This should be a turning point in how Mountain View manages its public landscapes and urban forest. We urge the City to adopt stronger safeguards, greater transparency and accountability, and a clear commitment to reducing and ultimately eliminating routine herbicide use.
Sincerely,
Silja Paymer, President, Tracy Ferea, Ph.D., Vice President, and Rashmi Sahai
GreenSpacesMV
Bruce England, April Webster, and IdaRose Sylvester
Mountain View Coalition for Sustainable Planning
Hala Alshahwany
Livable Mountain View
Shani Kleinhaus, Environmental Advocate
Santa Clara Valley Bird Alliance
Susan Hinton, Conservation Committee Chair
Sierra Club Loma Prieta Chapter
1 non-target terrestrial plants are plants other than the vegetation being treated, excluding aquatic plants.
2 https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1008Z5K.TXT&utm_source=chatgpt.com, see also https://www3.epa.gov/pesticides/chem_search/cleared_reviews/csr_PC-128821_30-Sep-05_a.pdf
3 https://www.accentnatural.com/300-trees-killed-by-herbicide-application/