Winter is a perfect time to inspect and clean shears, loppers, and saws before pruning shrubs and trees. If blades on pruning equipment were dull and nicked or tore plant tissue after cutting when they were last used, consider sharpening them or purchasing new blades. Replacement blades for Felco brand hand shears can be purchased at a fraction of the cost of new pruners. Even if blades of pruning equipment are sharp, they may need to be thoroughly cleaned to remove soil or sap left from their last use. Use a damp cloth or paper towel or simply soak blades in warm water for a short time to loosen debris. Make sure to dry the blades after washing them. For plant sap that is hard to remove, paint thinner can be applied to pruning blades and rinsed off after its use to prevent corrosion.
Pruning tools should also be disinfected to prevent the spread of pathogens among plants. Although it is not always practical to handle disinfectants when making multiple cuts on the same tree or pruning several trees or shrubs, it will minimize plant loss. Disease organisms may not be visible on tools, but they can be spread from plant to plant during pruning. Several products are available for disinfecting pruning equipment, including alcohol, chlorine bleach, trisodium phosphate (TSP), pine oil, or other household products.
Ethanol or isopropyl alcohol are ideal for sanitizing pruning equipment because blades can simply be wiped or dipped into disinfectant without a prolonged soak. Products sold as rubbing alcohol usually contain 70% isopropyl alcohol and can be used directly from the container. Ethanol can also be used without dilution. Both types of alcohol can be purchased at drugstores or variety stores. Like other flammable products, they should be stored away from heat sources.
Unlike alcohol, chlorine bleach should be diluted to a 10% solution before disinfecting blades of equipment. To prepare a 10% solution, mix one part bleach (using any brand available) to nine parts of water. When preparing a bleach solution, avoid inhalation of fumes, wear rubber gloves to prevent skin contact, and protect your clothing from bleaching. Use the bleach solution within two hours after it was prepared and soak blades of pruning equipment for 30 minutes. Because bleach solutions become 50% less effective as a disinfectant after two hours, make a new solution after this time. After soaking blades in bleach, rinse tools with clean water to prevent corrosion.Â Although chlorine bleach is inexpensive and readily-available, it is not as effective against viruses as some other disinfectants.
Household disinfectants, such as Lysol or household wipes can be used to sanitize pruning blades, but their effectiveness against plant pathogens has not been widely evaluated. While most household products are commonly available and are not generally corrosive, they are relatively expensive compared with other disinfectants.
Pine oil is available as a multi-purpose household cleaner at some retail outlets. Blades of pruning tools can be soaked in a 25% solution (one part pine oil to three parts water). While not as corrosive as chlorine bleach or TSP products, pine oil is also not as effective as bleach for disinfecting pruning equipment. Pine-Sol products currently sold in stores do not contain pine oil and their usefulness as a disinfectant for pruning tools is unknown.
Products containing TSP are relatively inexpensive when purchased at hardware, home-improvement, or other retail stores, but are corrosive to pruning blades. Products containing TSP are often sold as all purpose or heavy-duty cleaners for decks, siding, or for surfaces in preparation for painting. Like chlorine bleach, TSP products should be diluted to a 10% solution, using gloves to prevent skin contact with undiluted granular material. To disinfect blades of pruning shears, soak them in the 10% solution for at least three minutes before rinsing with water and drying them. While TSP products may be useful before pruning, the time required for soaking limits their usefulness during pruning.
Several multipurpose disinfectant products can be purchased from horticultural suppliers for greenhouse and field use. Some of these products, including Physan, Kleengrow, GreenClean, Greenshield, and MicroBLOC are labeled specifically for ornamental crops, non-food surfaces, packing lines (SaniDate), or cutting tools (ZeroTol). Some products require a ten minute waiting period after application, but do not require rinsing afterwards. Carefully read and follow label precautions when using these disinfectants.
Regardless of the disinfectant used, sanitizing tools during pruning is beneficial to minimize the spread of hard to control disease organisms that have few pesticides available for their control. Since there are many disinfectants available, chose the product that is most practical for your situation.
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REVISED: February 21, 2017