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Sterilise your pruning tools

March 14, 2011

Gabriel Hemery

I co-authored a pruning leaflet about eight years ago which has been a popular guide for woodland owners, managers and others who care for trees (see previous post).  However, there was a serious omission in the leaflet that has prompted an update: the importance of sterilising tools between trees, and between sites to reduce the risk of spreading infection.

The importance of phytosanitary control is now paramount, with the apparent increase in serious outbreaks of pests and diseases affecting our trees, such as Phytophthora ramorum (Sudden Oak Death) [apologies for incorrectly stating Acute Oak Decline in a former draft].  Knowledge about the impact on disease spread from pruning has existed for over a century: in the USA Waite and Smith (1906) linked fire blight (Erwinia amylovora Burrill) infections in plant nurseries to contaminated pruning tools.  More recently Goodman and Hattingh (1988) reported a 66% infection rate in trees pruned with secateurs treated with bacterial spot (Xanthomonas campestris pv. pruni Smith), although interestingly infection rates were only this high during cool and wet conditions.  The worst case of infection spread will come from pruning weeping bacterial wounds, e.g. cankers, where extreme care should be taken to clean tools after use – better still, wait until the oozing has dried up before pruning.  There is some evidence that even the best cleaning methods are ineffective at removing bacteria from the surfaces of cutting tools (Kleinhempel et al. 1987).

pruning tools to steriliseThe following action is recommended on sites where there is a biosecurity problem but I would go further suggest that it is good practice to follow these recommendations at all times.

Sterilise pruning tools between use on each tree by wiping with a cloth soaked in industrial methylated spirits (IMS).  You should also complete a more thorough sterilisation between sites, by soaking your tools in IMS.

Some suggest using household bleach, perhaps diluted nine parts water to one part bleach.  However, be aware that bleach is extremely toxic to plants, will ruin your clothes if splashed or dripped onto them, and it is a corrosive that will also spoil your tools.

After a hard day’s work in the garden or woods, and following disinfecting your tools using IMS as recommended above, rub some vegetable oil over the metal parts to keep your pruning tools in perfect working order.

Gabriel Hemery

The pruning leaflet is published by Woodland Heritage and available along with other practical leaflets from their website.

References

Goodman, C.A. and M.J. Hattingh, 1988. Mechanical transmission of Xanthomonas campestris pv. pruni in plum nursery trees. Plant Disease. 72:643. (link)

Kleinhempel, H., M. Nachtigall, W. Ficke and F. Ehrig. 1987. Disinfection of pruning shears for the prevention of the fire blight. Acta Horticulturae. 217: 211-218.

Waite, M.B. and R.E. Smith. 1906. Pear blight – its introduction, cause and treatment, and work of eradication. Californian State Horticultural Committee Special Report, 27 pp.

6 Comments

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  1. March 16, 2011

    Hello Gabriel
    Thanks for a very interesting post especially your comments ” There is some evidence that even the best cleaning methods are ineffective at removing bacteria from the surfaces of cutting tools”
    I have always tried to sterilize my secateurs and pruning saws from job to job so as not to bring in disease from other sites I have been working on.
    Your tip on using vegetable oil for general maintenance is good.

    • March 16, 2011

      Thanks Colin. Glad to hear that the post was of interest. I am having a writing spree about pruning at the moment. Expect one tomorrow on wound occlusion, and another about my personal pruning tool choice the day after. Thanks for sharing your experience too.
      Best wishes
      Gabriel

  2. Robina #
    January 12, 2012

    This site is so very clear and helpful. I need to sterilize my secateurs before pruning my autumn-fruiting raspberries. They’re showing leaves again, which is ridiculous for this time of year, and of course the stems are green inside.
    I’d thought maybe I should put them(the secateurs) into a low oven! Fortunately I didn’t.
    Your instructions are so clear and easy, and without jargon, thank goodness. I shall use it from now on.

    • January 12, 2012

      Thank you Robina. Pleased to hear that the information was helpful. Happy gardening.

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