Disinfect Download
Rachele Weishaar
It is important to clean and disinfect old pots each time you use them whether the pot is plastic, clay, or some other material. Disease-causing fungi and other organisms including insects can remain in old containers and the debris that accumulates in them, infecting the new plants potted in them.
Proper cleaning and disinfecting of pots requires just a minimum amount of effort, yet can mean the difference between the success or failure of containerized plants. Plus it allows you to reuse containers and reduce plastic waste.
To disinfect the pots, start by using a brush or rag to remove all the loose soil particles. Then wash pots in soapy water (dish detergent works great) and rinse clean. Soak the container in a solution containing one part household bleach to nine parts water for a minimum of 10 minutes and rinse. Prepare the solution by adding bleach to water (not water to bleach to avoid splashing) and protect skin and clothing from the bleach solution. Use the bleach solution within two hours of preparing it.
Sometimes a soak in 10% bleach for ten minutes is not practical or efficient, such as when you are trying to disinfect just one container. Rubbing alcohol can be used as an alternative disinfectant to 10% bleach. Clean the containers in the same way as described above but instead of soaking them in bleach solution, wipe all surfaces of the container (inside and out) with a cloth soaked in undiluted 70% isopropyl alcohol (rubbing alcohol). Alternatively, the container can be sprayed with rubbing alcohol, provided adequate coverage can be obtained.
TSP cleaners (often sold as deck or siding cleaners) are occasionally used as disinfectants for pruners and other garden equipment but are not practical, economical, and/or safe to use on containers. For this reason, it is not recommended to disinfect plant containers with TSP cleaners.
Household disinfectants like surface wipes, cleaners, and sprays (i.e. Lysol, Pin-Sol, Clorox wipes, Microban, etc) are a potential alternative to a 10% bleach solution to sanitize containers. These products are generally easier and safer to use than bleach. They are very effective at killing bacteria and other pathogens on surfaces and equipment in hospitals and schools, but their effectiveness at killing plant pathogens on containers and garden equipment has not been well evaluated. It is likely that these products could be effective at disinfecting containers, but a 10% bleach solution is preferred over these products because the formulations and active ingredients of household cleaners can vary by product and their efficacy on containers is not well known.
Disinfecting and sterilizing your horticultural tools is a good way to prevent the spread of disease-causing pathogens in your landscape. There are a number of products that can be used to disinfect tools and gardening surfaces, and each has advantages and disadvantages.
Cleaning and disinfecting are two distinct steps. Cleaning involves physically removing soil and debris and is the first step prior to disinfecting your tools. Soil and other organic residues reduce the effectiveness of disinfectants. Before disinfecting, always remove dirt, debris, or sap by wiping your tools with a damp cloth or paper towel.
The advantages to using household disinfectants, such as Lysol, to clean are that they're easy to find and most aren't corrosive. The disadvantage is that little research has been done regarding their effectiveness against plant pathogens. Additionally, household disinfectants are relatively expensive when compared to other disinfectants that can be used on horticultural tools. How you use household disinfectants will vary depending on what product you are using. Generally you will want to apply a full strength spray or dip; always be sure to read the label first. Commercial household disinfectants are widely available at a variety of stores.
Trisodium phosphates (TSPs) are inexpensive; the disadvantage is that they are very corrosive. To sanitize with TSP, mix a 10% solution (one part TSP to nine parts water) and let the tools sit in the solution for at least three minutes. When using TSP take care to avoid contact with your skin; the granules can cause nasty chemical burns if they stick to your skin and become wet. Many commercial TSP products are available at hardware stores and home-improvement centers. You may find TSPs in areas with painting products, as it's commonly used to clean surfaces prior to painting. Pay attention to the label; there are synthetic versions of TSP that are useless for tool disinfecting.
Pine oil products are not as corrosive as some other disinfecting products on the market, but they're also not as effective. To use pine oil products, mix a 25% solution (one part pine oil to three parts water) and then soak the tools in the solution. Many commercial products are available at grocery and hardware stores and at home-improvement centers.
Regardless of which product you choose, being diligent about keeping your tools clean is very important to keeping your plants healthy. A longer soaking may be needed for pruning surfaces that are not smooth. Ideally tools should be disinfected after working on every plant; however, this is usually not practical. If possible, rotate between several tools while working in the garden. That way, one tool can be disinfected while you work with another. After dipping your pruning tools, be sure to wipe away excess disinfectant to avoid injuringthe next plant.
Does your practice use alcohol or hydrogen peroxide to disinfect its Goldmann applanation tonometers? If so, you may risk exposing patients to infection. According to a 2017 Academy Ophthalmic Technology Assessment (OTA), the 3 most commonly used disinfectants are alcohols, hydrogen peroxide, and sodium hypochlorite (bleach); only the last was found to be effective disinfection against adenovirus and herpes simplex virus (HSV), the viruses commonly associated with nosocomial outbreaks in eye care.1
And good tonometer care does not stop with disinfection. Calibration is important for getting accurate and consistent monitoring of intraocular pressure (IOP), yet calibration protocols are often neglected.2
Because the GAT prism contacts the corneal surface, reusable prisms that are inadequately disinfected between patients can be a source of disease transmission. In fact, tonometer tips have been implicated in clusters of epidemic keratoconjunctivitis.3
The OTA panel evaluated 10 laboratory studies on disinfection of tonometer prisms and concluded that soaking in 10% bleach for 5 minutes afforded the most effective disinfection.1 This finding is consistent with the 2008 Centers for Disease Control and Prevention (CDC) Guideline for Disinfection and Sterilization in Healthcare Facilities4 and with recommendations of tonometer manufacturers.
Cost comparison. In a cost-benefit analysis of reusable versus disposable prisms conducted nationally in the United Kingdom, Jasani et al.7 noted substantial savings (2 million annually) with reusable GAT prisms. (However, the authors did not account for the added costs and time associated with disinfecting tonometer tips.) Tsai et al.8 found that Tonosafe prisms were approximately 8-fold more costly than reusable prisms.
Safety differences? Sterile, single-use tips have the obvious safety benefit of minimizing disease transmission between patients due to insufficient disinfection. Nonetheless, caution should be exercised even when applanating with a disposable prism. In an assessment of Tonosafe prism use at the Sussex Eye Hospital (United Kingdom), 16 of 35 questionnaire respondents admitted to touching the applanating face of the disposable prism prior to use, and Staphylococcus epidermidis and S. aureus were cultured from briefly touched prisms.10 This occurred despite respondents indicating that the reusable prisms were easier to handle and were unlikely to be touched on the applanating face during preparation.10
After cleaning your counters of dirt, it is time to sanitize. Check that your cleaning product is a disinfectant not just a surface cleaner. The product label should show it is antiviral and antibacterial. While surface cleaners will remove dirt and grime, disinfectants kill germs and sanitize your surfaces.
One of the final tasks is cleaning, disinfecting and putting away tools. Quality gardening tools are not cheap and should be carefully maintained before storing. Simple cleaning is not always enough because our tools frequently come into contact with diseased garden plants that harbor bacteria, fungi or viruses. To prevent disease transmission to plants next year, tools should be subjected to a two-step cleaning and disinfecting process.
Once cleaned, the tool can then be disinfected to kill plant disease organisms. Gardeners have access to many home disinfectants but not all are considered equal in their ability to kill bacteria, fungi and viruses.
For fire blight, these three disinfectants can be diluted to one-part disinfectant to four-parts water and still be effective. After removing tools from the soak, an important step in the disinfection process is to allow the tools to air dry rather than wiping them dry.
While Clorox, Lysol, and Pine-Sol are quite effective at controlling this tough bacteria, an important consideration is the corrosiveness of the chemical compounds. Bleach and Pine-Sol are known to corrode metal tools. Rub some linseed or mineral oil on the metal after disinfection to prevent rusting over the winter.
Unfortunately, there are few tool disinfection studies for disease organisms other than fire blight. However, the general rule of thumb is to soak your tools for a longer period of time if the metal is pitted or if there are lots of nooks and crannies.
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