Integrated Pest Management

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 in 2013, the City of Palo Alto will not be providing pest control measures on public trees this year.  Residents interested in pesticide applications on public trees will be encouraged to contact the Urban Forestry section for a public tree care permit allowing them to obtain services from a private certified pest control applicator (PCA) at their own expense.  Please call (650) 496-5953.


IPM techniques include:

  • 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.
  • 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, use Indian named cultivars of flowering crabapple in place of other cultivars for resistance to fire blight, 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.
  • 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).
  • 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.

Pesticides are only used as a last resort and only when pest monitoring indicates they are needed. The city arborist will make a determination for when a treatment may be required (e.g. certain number of pests per leaf, level of honeydew present) and how it will be implemented. Pesticides used must be the least toxic, most target-specific and effective materials available.

Last Updated: Feb 28, 2013