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How to use Pocket Diagnostic® rapid test strips for plant diseases

The following page describes the simple process of using Pocket Diagnostic® lateral flow rapid test strips for plant diseases. The Pocket Diagnostic® range will detect a number of plant pathogens such as Phytophthora spp. (Potato blight, Sudden Oak Death, ramorum blight), Erwinia amylovora (Fire blight), Potato virus Y and Ralstonia solanacearum (Bacterial wilt/Brown rot).

All tests operate in the same way. However, there is a slightly different approach when testing wood samples.

  1. Select a sample (as detailed below)
  2. Cut or tear sample into small pieces and put into bottle containing buffer and ball bearings
  3. Shake firmly for 30-60 seconds to break up the sample and allow the liquid to settle
  4. Draw liquid into the pipette – avoid sample debris and air bubbles
  5. Keeping the test device level, add 2 drops into the sample well of the device
  6. Valid results within 10 minutes
Using Pocket Diagnostic

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Always read the instructions provided with the kits before use. 


VIDEO: Adding a sample to a test

The video below shows one of our tests being used in the field. The test being used is our Phytophthora rapid test but this user-method is the same for all of our tests.

Sample Preparation

Sample Preparation

Select symptomatic plant material from where the healthy material meets the diseased material. As a general rule, we recommend that the sample should weigh approx. 0.2g or 25x25mm in size. It’s important to wash any soil and other debris from the plant material sample prior to adding to the bottle.

Selection of the most appropriate sample ensures accurate and reliable results.

The unique ‘bottle and ball’ sample preparation method sufficiently breaks down plant material after only 30-60 seconds of shaking. After shaking the sample should be left to settle prior to a few drops being removed from the top of buffer and added to the tests device.

This easy and clean approach enables Pocket Diagnostic® plant disease tests to be used on the following plant material:

  • Leaves
  • Shoots
  • Roots
  • Flowers (cut into small pieces)
  • Bark (cut into small pieces)
  • Woody material (cut into small pieces)

Hard materials may require slightly longer shaking to ensure adequate sample breakdown.

Interpreting Results

Test Interpretation

One line present only at the C line indicates a negative result.

Two lines present, at both the T and C line, indicates a positive result.

The absence of a line at C indicates the test has failed and must be repeated.


Positive and negative LFDs

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Example of a test used incorrectly

Below is an example of what can happen if too much debris and plant material are added to the test strip. There is too much debris preventing the test from working properly. Hence why it has not run properly.

plant disease tests incorrectly used

Flooded sample well and viewing window

Always read the instruction before using Pocket Diagnostic®.

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