Integrated Pest Management

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.

The life stages of the beneficial lady beetle

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.

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

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 (left) and early and later instars (right)

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.