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Pest and Disease Analysis

How to Collect Plant and Insect Samples for Problem Diagnosis

Accurate identification of the pest or disease attacking your plant is crucial to effective treatment. The Master Gardeners can help you identify many common pests and diseases in the home garden. However, there are new plant pathogens arriving in Hawaii every year and your Master Gardener volunteers may not recognize the sample you bring in. Fortunately, there are experts at hand.  Submit plant or insect samples to the Agricultural Diagnostic Services Center

  • To get accurate identification of pests and diseases attacking your plants, especially unusual samples
  • To get an effective research-based treatment plan

Collecting plant samples for diagnosis can be a bit complicated. Because plants in Hawaii are prone to attack from a multitude of diseases and pests, there may be more than one problem present in the plants you submit. Additionally, there may be all kinds of different symptoms present on one plant. That is why it is important that you examine all parts of the plant and submit samples of every part that is affected. A leaf may not be enough if the plant also is showing symptoms in the roots, stem, and blossoms. Please read the article below carefully before collecting your samples. You may need to collect samples from several different plants in order to show the progression of the disease or pest development (e.g. egg, larvae, pupae, adult)

How do I Collect Plant and Insect Samples?

For complete directions, consult the CTAHR publication “Collecting Plant Disease and Insect Pest Samples for Problem Diagnosis” at the following link:

  • Bring in samples from various parts of live plants showing typical symptoms.
  • Consult the “Collecting Samples” publication for instructions on submitting live or dead insect samples. Some should be submitted live for accurate diagnosis. Always submit suspected samples of Little Fire Ants in rubbing alcohol or frozen in a ziplock bag.
  • Bring in samples that represent the progression of the disease or stages of insect development.
  • Bring in photographs if these provide a better representation. Photographs should be taken from the front so that they show the whole plant, not from the top. Close-ups may be helpful as well, as long as they are in focus.
  • Note the environmental conditions (location, elevation, hours of sun, wind).
  • Note fertilizer, pesticide and irrigation practices.

Specific instructions for collecting and preserving different types of insect and plant samples can be found at the link above.  You will also find a worksheet to help you record necessary information as well as color photographs of some of the more common pests and diseases.

The Agricultural Diagnostic Service Center charges a small fee for this service. Bring your sample, or mail it, to the Cooperative Extension Service (CES) at 875 Komohana Street in Hilo. Copies of the fee schedule are available at the CES office or online at the following link.

The results of diagnosis will be sent to you by mail, along with management options.

Submitted by Kendal Lyon, Hawaii Island Master Gardeners
Photo credit:  Sandra Osborne