Integrated Pest Management

Public Tree IPM

Integrated Pest Management (IPM) is a strategy that focuses on long term prevention of pest problems with minimum impacts on human health, the environment or non-target organisms. The City of Palo Alto adopted a reduced risk pest management policy in 2001. This policy requires that each division that applies pesticides maintain an active IPM plan in order to reduce or eliminate chemical usage as much as possible. 

In an effort to reduce pesticide use the City of Palo Alto has not provided pest control measures involving use of pesticides on public trees since 2012.  Residents interested in pesticide applications on public trees are encouraged to contact the Urban Forestry section for a public tree care permit(PDF, 2MB) allowing them to obtain services from a private qualified pest control applicator at their own expense. Pest control businesses and companies that offer pest control services are licensed and regulated by the California Department of Pesticide Regulation and the Santa Clara County Division of Agriculture.

IPM Techniques

Encourage naturally occurring bio-controls

Examples of naturally occurring bio-control - lady beetles, lacewings, parasitic wasps, predatory mites, spiders, earwigs, insectivorous birds, bats, etc. Use plants that attract the above, provide nesting, etc.

Life Stages of the beneficial Lady Beetle - Eggs, Pupa, Larva and Adult

The life stages of the beneficial lady beetle

Use alternate plant species or varieties that are less susceptible to pests

Examples - use ‘Frontier’ elm or Asian elm species for Dutch Elm Disease resistance, plant powdery mildew resistant cultivars of crape myrtle, plant species other than Chinese or European hackberry that are less palatable to honeydew producing hackberry woolly aphid, utilize plants that are resistant to oak root fungus when planting in known sites.

Closeup of woolly hackberry aphid wooly hackberry aphid on leaf with honeydew

Woolly hackberry aphid up close (left) and on leaf with honeydew (right)

Use cultural practices that reduce pest problems

Examples - avoid sprinkler irrigation around plants that are susceptible to anthracnose such as Chinese elms, do not irrigate around the trunks of native oaks in the dry season, thin out canopy to reduce foliar disease problems, prune trees at certain times of the year to reduce pest problems (e.g. prune pines and elms in the winter to avoid bark beetle attack), remove diseased or bark beetle infested trees before the pest can spread, proper disposal of pest ridden material, provide proper irrigation, fertilize only as necessary, keep plants healthy by providing suitable conditions for that species, power wash insects off the tree (e.g. Western Tussock Moth egg masses).

Western tussock moth egg mass Closeup of early and later instars

 Western tussock moth egg mass (left) and early and later instars (right)

Change habitat to make it incompatible with pest development

Examples – plant trees at or slightly above grade to reduce crown rot problems, clear bay trees away from specimen Coast live oaks where Sudden Oak Death is a problem. 

The Urban Forestry Section only uses pesticides in rare and extreme cases. An example of such a case would be an outbreak of an invasive pest, a new plant disease or an invasive plant species. Chemical options are only used as a last resort and only when monitoring indicates they are needed. Qualified Urban Forestry Section staff will make a determination if a treatment may be required and how it will be implemented. Pesticides used must be the least toxic, most target-specific and effective materials available.




Please call (650) 496-5953 for more information.