THE MYTH: The best way to disinfect pruning tools is to use a bleach solution.
THE REALITY: A common and much-debated garden myth is that a chlorine bleach solution is the best way to disinfect pruning tools. So popular, in fact, that a Google search on the topic comes back with 1.7 million results!
The consensus among reputable extension offices’ publications and scientific sources is that a chlorine bleach solution is not the best method for disinfecting pruning tools.
Dr. Linda Chalker-Scott, Associate Professor and Extension Specialist at Washington State University, has authored two of the more substantial articles on this topic: “Sterilized Pruning Tools: Nuisance or Necessity?” and “The Myth of Cloroxed Clippers.” In these articles, and in the other sources referenced below, the authors question when and how often tools should be cleaned, and explain why other disinfectants are preferable to chlorine bleach.
Tools should be disinfected commensurate with the type of pathogen that is potentially being transmitted. It has been suggested that soilborne and airborne pathogens are more likely to be transmitted by hands and clothing, while viruses, vascular system diseases, and cankers are most likely to be spread by pruning tools. However, chances are the gardener does not know what type of pathogen is present, or whether the plant is even diseased. The conservative approach is to disinfect pruning tools in the field. The consensus is to disinfect tools between cuts, especially if the plant is known to be diseased, and between each plant. If the plant appears to be healthy, disinfecting after every few cuts is acceptable.
Among the publications researched there is also agreement that a bleach solution is not the best disinfectant for pruning tools. Chlorine bleach is corrosive, which means it can cause tool pitting and damage over time. The pits caused by the corrosion can then harbor microbes that may further damage plants. Chlorine bleach can harm skin and eyes if it comes in contact with them, and produces harmful fumes which can affect the nose, throat, and lungs.
The better alternative? Stick to household disinfectants (such as “Lysol”), the popular mouthwash “Listerine,” or a rubbing alcohol solution.
- Chalker-Scott, Linda, Sterilized Pruning Tools: Nuisance or Necessity?
- Chalker-Scott, Linda, The Myth of Cloroxed Clippers
- French, Susan C. and Bonnie Lee Appleton, A Guide to Successful Pruning: Pruning Basics and Tools
- Lerner, Rosie et al., Pruning Ornamental Trees and Shrubs
- Penn State Extension, Disinfecting Tools, Equipment, Pots, Flats and Benches
- Schalau, Jeff, Sanitizing Pruning Tools
- University of Florida Extension, Disinfecting Your Garden Tools