I used to be a scientist (now a patent lawyer) but my Ph. D. is in organic chemistry not biology. So with that disclaimer and to explain in lay terms.....much depends on the type of virus, its mechanism of infection and what we are trying to disinfect. Enveloped viruses that attach via the envelope (like lipid/fat hooks in case of coronavirus) to infect a cell can be deactivated if one gets rid of their envelope (like with soap or alcohol which would destroy the envelope/hooks comprising fats/lipids). However, if the virus infects by other means and does not have an envelope, one would need to break down the protein structure. This is where I guess the power of bleach comes in. Again, if you have a porous surface, like a terracotta pot, it would be harder to "kill" the virus without using extreme measures than if it were say a plastic pot. Here is something that would help with understanding how virus work https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4788752/

I'm a retired bacteriologist. Getgoing_100 is spot on. The great majority of plant viruses are surrounded by a rigid protein structure rather than a lipid membrane with proteins embedded in it (as in the case of SARS CoV-2). Soap and alcohol are not very effective in disrupting the plant virus structure. Bleach (hypochlorite) is a fantastic disinfectant. It damages proteins and also inactivates the nucleic acid genome. Stick with your bleach!

Thanks for great information.

So, what you are saying is that alcohol will not be efficient cleaning cutting tools? Wiping knife blades, straight edge, clippers will not be safe? Only bleach?

Bleach tends to destroy or dull knife, cutting blades. I understand about clay pots and will continue soaking them in bleach. I guess I'll go back to using a flame on the cutting tools.

My understanding about dish detergent is that is will dissolve lipid (fat) layers. Also, alcohol does disinfect as it is recommended by 'experts' to disinfect hard surfaces such as counter-tops, doorknobs, etc. It is also recommended to only use a 70% alcohol hand sanitizer.

If I'm understanding you correctly, orchid virus differs in composition from Covid? Therefore, alcohol and detergent would be ineffective?

Jane

That was a great question and I appreciated reading the responses in lay terms! Thank you!

Alcohol, soap and hydrogen peroxide all have a place in disinfection routines as they are all effective against most bacteria and fungi and at least some viruses. Also, even if they don't "kill" all viruses, they may aid in physical removal of viruses from at least non porus surfaces. Eventually, it is about how thorough one wants to be in trying to reduce plant viruses.

All viruses have some kind of nucleic acid genome (genetic blueprint); but SARS CoV-2 and orchid viruses differ in how that genome is packaged and delivered into cells. So you've got that right -- soap and alcohol will disrupt the packaging and delivery of SARS CoV-2 but poorly if at all work on orchid viruses. As for cutting tools, I'm with you, that bleach is too harsh. I dip in alcohol and then ignite and burn off the alcohol (old bacteriology habit), but flame alone is fine, if not better.

Jane, great question and I pray you are safe))

Mike

Thanks, Mike. I am safe and hope you are also. Being stuck in the house, thinking about the spread of Covid, led me to think about orchid viruses. Very good information from Miniplants and Getgoing! Nice to have scientists on board!

I realize once a plant is virused it is contaminated. Because I have so many plants I can't test them all and work with them with the assumption that they could have virus even though they show no signs of it.

Dealing with so many plants during repotting, I am always looking for ways to lessen the burden of sanitizing. Hearing information about Covid regarding sanitizing surfaces got me thinking about using alcohol as a wipe for tools.

My understanding is that alcohol should air-dry and not be wiped off. Or soap and water for 2 minutes would cause the breakdown of the lipid layer surrounding the Covid virus. I was interested to find out if soap and water would do the same with orchid virus rather than using bleach. I realize the various orchid viruses might be different from Covid.

Right now, bleach is in short supply. Alcohol is in short supply. I always purchase alcohol in full amounts (99%) and dilute it down to 70%. I've used this for many years sanitizing tools which I use on orchids and other plants. Usually, I keep a container of alcohol filled with alcohol on my potting bench and let the cutting tools soak for a few minutes before using again,

I guess my curiosity about soap and water led me to think that possibly soaking clay pots in Dawn dish soap and water could work on orchid pots rather than bleach (which is what I've always used in the past). I have a lot of orchids and a lot of clay pots. I could see using soap and water and soaking the pots overnight and that might be sufficient. I would still use alcohol for cleaning tools.

My other thought, living in Florida, the sun is hot. If pots were left out in the sun for a few days, would that work? I could line them up all over my lawn!! Let them bake out there.

Thanks again, everyone

Jane

Unfortunately, I don't think the sun would be a reliable virus deactivator in this case. For one, effect of sun on virus differs for different viruses. Some viruses aren't deactivated despite some damage to the nuclei acid chain while others are capable of healing themselves! Also, the exposure to sun would be unreliable in a porus substance like a clay pot.

How long could a virus stay viable? If pots were stored in a dry shed/garage for a year would the virus still be dangerous?

Sorry to ask so many questions, but I wonder how many safety concerns regarding the viability of virus over time should be a concern?

In my situation, I have so many plants. I try to repot annually or every two years. I tend to take the old pots and pile them up in the garage or a small shed. Usually I soak them in bleach for a few days, then hose them off, shrub them with brushes and let them dry in the sun for a few days to inactivate any remaining bleach before repotting in them.

I'm reading about Covid Virus and they say that the virus can live for a few hours on hard surfaces and a shorter time on fabrics. No mention of porous items such as clay pots. Also, UV light can kill the virus. That is where I'm thinking strong sunlight would work.

Jane

Jane, fortunately the covid 19 virus is easily deactivated. Unfortunately, plant virus aren't. Here is an article you may have seen before but it makes and interesting read. https://staugorchidsociety.org/PDF/AOS17-Virus.pdf

I am guessing you could put your clay pots in an oven at 400F for 3 hours and have peace of mind without having to use bleach.

here is another article that deals with exactly the questions you raise. The author appears to be in the same situation as you. She recommends a two step process using lye and viskon S for easier disinfection routines for tools. https://www.aeorchids.com/orchid-culture/orchid-virus-disinfection/

A good place to get around the bleach shortage is a pool supply store! They are well stocked, (at least here)..one 7 dollar packet of pool shock will make dozens of gallons of bleach. It comes in a granular form.