Organic Pest Control

The first step is Prevention. It is far better to avoid pests than to combat them. How do we prevent pests and diseases?

  1. Keep plants healthy: Give them good soil, and the right amount of water (not too much or too little).
  2. Selects plants that are disease resistant and adapted to our climate: Plants have many varieties, and some varieties are far more resistant to diseases than others. The easiest way to find out of it is resistant or not is to go ahead and plant it. If it has problems with diseases, simply plant another variety.
  3. Encourage beneficial life: Keep the soil loaded with microorganisms (add compost), encourage beneficial and predacious insects by planting a variety of plants, reducing monocultures and avoiding pesticides.
  4. Exclude pests: Use floating row cover, bird netting, and ensure herbicides and other chemicals stay far away from our plants.

The next step is Diagnosing the Problem.  Make sure you know what you are having trouble with before you fight it! Diagnosis isn’t as hard as it might seem, there are lots of resources out there.

  • Start with most obvious and work backwards towards less obvious
    • The most common problems in plants are cause by humans: watering, mis-planted,  mechanical damage, herbicide damage
    • Weather can also play a huge role in how our plants are doing: Hail damage, high temperatures, freezes, etc.

Many times multiple problems occur

The majority of the time a plant shows symptoms of stress, it is caused by factors other than disease or insect pests.

When trying to diagnose a problem, ask yourself the following questions:

  1. Is the plant receiving proper care and placed in a proper environment?
  2. What could have been done to the plant that might cause these symptoms?
  3. Can I see any insects or signs of disease?

If you still don’t know what it is, take a sample to County Extension Office.

Once you know what your pest is the next step is determining if you need to treat or not.

Two items to consider are economics and ecology.

  1. Does the cost to fix the problem cost more than or almost as much as the plant itself?
  2. Will I maintain proper care of the earth and my surrounding garden by doing this treatment option?

Treatment Options:

Natural controls: Let nature take care of itself, and encouraging healthy plants

Applied Control

  1. Biological: Addition of insects, bacteria and other beneficial organisms. (Adding ladybugs, praying mantis, other pest specific controls)
  2. Mechanical: Removing pests by hand or excluding them.
  3. Cultural: Modifying the environment or conditions. (Changing watering schedule, using resistant plants, rotating crops)
  4. Chemical control: Organic chemicals to use can include diotomaceous earth, insecticidal soap, and horticultural oils

Top 10 Tips:

  • Keep the soil alive and heathy
  • Plant tolerant and resistant varieties.
  • Reduce large monocultures and rotate crops.
  • Plant a variety of plants.
  • Maintain deep, less frequent irrigation.
  • Ask if treatment is really necessary.
  • Know what you are treating before you treat it.
  • Remove plants with disease. Keep area and tools clean to avoid spreading pests.
  • If you have had problems with a certain plant, try planting something else or putting the plant in a different spot.
  • Don’t worry too much: plants can survive many problems and still produce well.


  • Local Extension office
    • Plant Pest Diagnostic Lab (send them a sample and they identify the problem)
    • Fact Sheets on specific plants
    • Plant Pest Advisories  including one specific for vegetable crops
  • Pacific Northwest HandbookHandbook of pests, diseases and weeds. Easy to look up pests based on plant
  • Books:
    • Many for organic gardening by Rodale Inc
    • What’s Wrong with my Vegetable Garden? By By David Deardorff and Kathryn Wadsworth

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