Sterilizing Cutting Tools

sterilize cutting tools by heat;
old-fashioned, but still effective

One of the perennial problems in gardening is how to clean gardening tools after using them, especially cutting tools. Dirty cutting tools can spread diseases quickly, but how do you sterilize something that's full of dirt ? There are some time-tested ways to do the job, especially necessary with disease-prone orchids. In most instances, you don't really have to sterilize a shovel or an ax.  Many soft-tissue tropical plants, though, can contract a number of diseases spread by cutting tools. It is usually wise to sterilize cutting tools when cutting into orchids or members of the Aroid family. Some fairly recent ( and lethal on a large scale) diseases such as Texas Phoenix Palm Decline, Laurel Wilt and Sudden Oak Death can be readily transmitted by cutting tools.

useful, but very corrosive to tools !

In the home garden, cleaning hand tools is easy. For decades, orchid growers have sterilized their pruners and knives with a range of products, but I prefer to use either heat from a propane torch or to soak tools in a TSP ( trisodium phosphate) solution  to sterilize tools. Either technique will nicely rid your tools of any pathogens that may harm your plants. The disadvantage to using high heat is that you will discolor tools, and possibly ruin their smooth finish after repeated heatings.  TSP is hard to find in some states with regulations about phosphorous, but it is sometimes available in paint-supply stores to use for cleaning walls before painting them. It will retard rust or corrosion, and leaves no residue on the tools.  

useful, and will not corrode tools

To sterilize larger tools such as shovels, saws, and loppers, wash them off with a garden hose after using, and dip them in TSP or germicidal soap solutions.  Rinse off the soap, then spray the tool heads with light oil to keep them from rusting. Disease transmission in plants is a larger issue than people may realize, and in some cases, a single cut into a clean plant can infect it if the tool was previously used on an infected plant. Some bacteria and several fungi can rapidly infect a plant, sometimes within hours of transmission into a cut surface. 

Virus Infection in Phalaenopsis

Virus Infection  in
Cattleya Orchid
Orchid growers need to be especially careful about virus and other pathogen transfer from plant to plant via cutting tools. Orchids are among the most disease-sensitive of commercially grown plants. Repotting orchids calls for the greatest degree of sterilization with cutting tools. While many orchids are very disease-resistant, some are especially prone to get diseased, especially in intensive greenhouse or high-density growing conditions. It is common to see growers grow their plants with high density vertical stacking, hanging one plant underneath another, underneath another. In some cases I have seen 12 plants strung together in a column. If the plant on top of this column of plants becomes diseased or infected, it can infect the entire column in a matter of days. This is a very expensive loss ! 

Erwinia Bacterial Infection in
Calla Lily
One of the most productive tactics to employ when cutting into plants is to use a sterilized cutting tool, and keep 3 or more cutting tools clean and ready to use. When you finish cutting into a plant, set the used cutter aside, and use the next tool in the line. When you get to the last clean tool, re-sterilize the group, of tools and start anew. This chain-of-use system is easy once you get used to it, and can save a lot of plants from becoming infected. This method becomes an automatic part of your skill set when working with certain plants. If you know that certain garden plants are are susceptible to cutting-transmitted diseases, it is easy enough to heat-sterilize a shovel or ax or blade with a propane torch. It may sound like a lot of trouble, but these tactics only take a few seconds, possibly saving a plant in the process.    
Craig Morell
Pinecrest Gardens

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