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Common Garden Pests and Diseases

Contact Us - States Analytical Laboratory

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Pests and diseases can be a problem in any environment. Please see the downloadable leaflet for an in depth look at most common species found in Guernsey and the control methods. The documents also includes which pesticides are available for garden use and how to use them effectively.

Please remember, if using pesticides ALWAYS READ THE LABEL: USE PESTICIDES SAFELY.

Common environmentally harmful species on Guernsey are:

  • Honey Fungus

    • Honey Fungus or Armillaria is probably the largest killer of woody plants on the island and is difficult to control. 
    • For more information download the pdf icon Honey Fungus Leaflet [672kb], which is a guide to the identification and control methods. You will also find information on the plant species that are most tolerant of the fungus.
  • Japanese Knotweed

    • Japanese Knotweed is the most invasive plant in Guernsey. It spreads rapidly, especially next to streams. It can out-compete and destroy native plants, flowers and habitats and is difficult to control.
    • It can re-grow from tiny cut fragments of the plant; maintenance by mowing, strimming or flailing the plant may help, not hinder, its spread
    • Advice on how to control Japanese Knotweed in the garden or using professional herbicides is available in the pdf icon Chemical Control of Japanese Knotweed 2020 [477kb] pdf icon Control of Japanese Knotweed [354kb] leaflets. Further information is available under the downloads section.


The States Analytical Laboratory provides a range of services to accurately identify pests, diseases and disorders of horticultural and agricultural crops, as well as garden and native plants.

Please contact us if you require further information.


Common Garden Pests & Diseases 2020 Honey Fungus 2020 Chemical Control of Japanese Knotweed 2020 Control of Japanese Knotweed (Home & Garden Situation) 2020

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