Integrated Pest Management: Healthy Gardens

The Sonoma Master Gardeners' website, and several UC websites contain a wealth of information on pests, bugs, plant diseases and disorders, and methods to control those.

Integrated Pest Management is a great way to promote healthy gardens.  A healthy garden has plants, animals, insects, and microbes working together to make a beautiful landscape.  Like the planet itself, there are “good guys”, “bad guys” and “neutral guys”.  If the entire system is working together, often the no single pest can build up to damaging populations.  If a pest does build up to damaging levels, IPM offers solutions that promote preserving the balance of life in the garden, starting with cultural controls and moving up to less toxic pesticides only if necessary.

What is a Pest?

Pests are organisms that damage or interfere with desirable plants in our gardens and orchards. They may disfigure plants, transmit diseases, damage crops. A pest can be a vertebrate (bird, rodent, or other mammal), an invertebrate (insect, tick, mite, slug or snail), a nematode, or a pathogen (bacteria, virus, or fungus), or a weed that competes with the desirable plants.

What is Integrated Pest Management?

Integrated Pest Management, or IPM, seeks to control pest problems with a combination of techniques that minimize damage to plants as well as people and other living creatures.

IPM involves

• minimizing problems by using good gardening practices
• recognizing problems as early as you can and deciding whether they can be tolerated
• identifying the source of the problem
• determining appropriate measures to control the problem
• if you find it necessary to use insecticides or herbicides, using them safely

Recognizing Problems

Keep an eye out for problems.  Deal with them early, before they get out of hand.  Be aware that the presence of insects does not necessarily indicate a problem - predatory insects will help you control other insects, and bees and other insects are necessary for pollination.

If there are pest-caused problems, the first steps are identifying the pest and deciding whether its effects can be tolerated or if the problem warrants control. Temporary leaf damage, for example, will not seriously damage a plant. Neither is loss of a few tomatoes or roses. In such cases, doing nothing and waiting for the pest to leave or for predatory insects to control it may be the best solution (see Natural Enemies Gallery).  Continued damage over many weeks may call for action.

Wilting can be from either over-watering or under-watering.  The first thing to check is the soil around the plant.  The surface may appear damp while the root zone is dry or saturated.  Use a probe made to test soil moisture or dig a small hole a few inches deep near the plant, or simply stick your finger in and feel the soil.  If the soil is dry, water it.  Check your irrigation system and your timer, if you use one.  You may need to install a new irrigation system or overhaul the existing one.

Wilting can also be the result of gophers eating the roots  (See Gophers)

Holes in leaves can be caused by a variety of vertebrate pests deer, rodents, birds, mollusks (snails and slugs), and insects.  Dead or dying leaves or branches may be caused by plant diseases or abiotic factors.

A wealth of information on recognizing problems on specific plants is available on the University of California IPM website.  Some of the helpful tools available on the UC IPM website are

Home, Garden, Turf, and Landscape Pests

Quick Tips  - short reviews of certain specific pests

Pest Notes - longer, 3-4 page detailed analyses of pests

Natural Enemies Gallery - expanded list of Good Bugs

Weed Information, including a Weed Photo Gallery and a very useful Key for Identifying Weeds

If you cannot identify the problem and its source, ask a Master Gardener at our Information Desk or at Information Tables at farmers markets, fairs and other events.

Controlling Problems

Start by using the least toxic method - use chemical pesticides as a last resort.

Non-toxic methods include

• hand picking insects off of plants
• using sticky insect barriers and traps
• spraying with a strong stream of water or insecticidal soap
• encouraging beneficial insects that prey on other insects

Less-toxic methods include

• spraying horticultural oils, such as Neem oil
• applying dormant sprays on woody plants to control some fungal and insect problems
• applying diatomaceous earth (DE) to control slugs, snails, grubs and other insects
• applying Bacillus thuringiensis (Bt) to control certain larvae

If you find it necessary to use insecticides or herbicides, select the appropriate product and use it safely.