I saw a busy squirrel preparing for winter. He goes around the neighborhood, collecting acorns from all the oak trees. Like our wildlife, gardeners are busy with late-season activities.
One of the last tasks is to clean, disinfect and dispose of the instruments. Quality gardening tools are expensive and must be carefully maintained before storage. Simple cleaning is not always enough, as our tools often come into contact with diseased garden plants containing bacteria, fungi or viruses. To prevent disease transmission to plants next year, tools will need to undergo a two-step cleaning and disinfection process.
The first step is to remove any remaining dirt, sap, and debris. A stiff brush or soapy sponge will help remove dirt effectively. Alternatively, you can use a powerful jet of water to loosen the soil.
After cleaning, the instrument can be disinfected to kill plant pathogens. Gardeners have access to many household disinfectants, but not all of them are equally capable of killing bacteria, fungi and viruses.
One of the worst pathogens that can survive on tools such as saws and pruning saws is fire blight that attacks apple and pear trees. The University of California conducted an experiment testing the ability of Clorox® bleach, Lysol® concentrate, Pine-Sol®, rubbing alcohol (70%, 91% and 99%), Listerine® mouthwash and peroxide of hydrogen to extinguish fires. destroy bacteria and prevent the transmission of diseases to instruments. Of the products tested, the most effective method was to soak the instrument in Clorox, Lysol, and Pine-Sol for one or more minutes.
To combat fire blight, these three disinfectants can be diluted at a ratio of one part disinfectant to four parts water and still remain effective. After removing instruments from the soaking bath, an important step in the disinfection process is to let the instruments air dry rather than clean them.
While Clorox, Lysol, and Pine-Sol are very effective at killing these stubborn bacteria, the corrosive nature of the chemicals is a major factor. Bleach and Pine-Sol are known to corrode metal tools. After disinfection, rub the metal with a small amount of drying oil or mineral oil to prevent rusting in winter.
Unfortunately, there is little research on instrument disinfection for pathogens other than fire blight. However, as a general rule, if the metal has holes or a lot of rough edges, you will have to soak the tools for an extended period of time.
I personally use both disinfectant and bleach. I would prefer to disinfect all my tools with undiluted Lysol® All-Purpose Cleaner as it will not damage the metal. However, this is not economical for tools and larger items. This is why I soak small hand tools like shears and hand saws in Lysol for 2-3 minutes. These are also the instruments most often handled in fire burns. For larger tools like shovels and tomato cages, I use a solution of 1 part bleach to 9 parts water as a disinfectant in a large bucket.
Esther McGinnis is a gardener at NDSU Fargo and an occasional contributor to the Dakota Gardener column.
