Sanitizing tools for virus control

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I just came across this when looking up how to disinfect potentially virus-contaminated soil and gardening equipment. I had searched on "Does soap kill tobacco mosaic virus?" TMV is related to odontoglossum ringspot virus, ORSV.

TSP below is trisodium phosphate, a cleaning agent. Standard household bleach is a water solution of NaOCL, sodium hypochlorite, and is sold as 2.75% weight by volume. A 1 part bleach with 9 parts water dilution gives 0.275% NaOCL. The source I linked makes clear that fresh milk or reconstituted powdered skim milk kills TMV.

Of note,

In 1960, Hare and Lucas tested the effect of pH and milk on TMV particles. The largest number of lesions occurred at pH 6 to 7, with lower counts at pH 8 and nearly none at pH 10. Lesions were reduced at pH 4.4 and almost none at pH 3.1. At a pH lower than 3.1 or higher than 10 no virus particles recovered.

Milk inactivated the virus almost 100 percent at pH 6.7 but if the solution was diluted significantly nearly all of the virus could be recovered in the active form.

...

In 1989, Pategas, Schuerger and Wetter investigated an outbreak of ToMV in hydroponic peppers which caused necrotic local lesions and leaf drop. They showed ToMV 70 percent transmission on untreated shears. Treatment of shears with 10 percent TSP showed the least transmission at 3 percent. Using 0.26 percent NaOCl and 0.01 percent Ivory Liquid resulted in 17 percent transmission while 0.26 percent NaOCl alone gave 22 percent. The quaternary ammonium RD20 allowed 39 percent when used at 0.4 percent. Solutions that were ineffective were rinsing in sterilized deionized water, 70 percent ethanol or 0.01 percent Ivory Liquid alone.

...

n 1994, Hu, Ferreira, Xu, Lu, IHA, Pflum and Wang evaluated disinfestants for Cymbidium Mosaic Virus and ORSV in orchids. When plants were inoculated with CyMV they found the virus in inoculated plants in 3 days and it readily became systemic over time. ORSV was not typically systemic. Skim milk was not effective on CyMV. Table 1 shows the effects of various concentrations of bleach or sodium hydroxide on transmission of ORSV. Use of bleach at 10 to 20 percent was 100 percent effective but phytotoxic and damaging to tools. Use of NaOH was 100 percent effective at rates between 1 and
20 percent.

...

Finally, when we saw the outbreak of TMV in petunias early this year, a number of people shared some details of their unpublished work on TMV. LaMondia who was working in the tobacco industry at the time, stressed the need for repeated hand washing or wearing gloves and no smoking. All tobacco products have tested very high for presence of TMV. Washing hands well with soap and water has the best impact on virus removal and inactivation.

[SundayGardener]

Does the Ph refer to the Ph of the milk being applied to the plants?

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If you are addressing the first part of the quote... I didn't read the original report, but my interpretation is that the first part of the quote describes altering pH alone to treat virus, without milk, and the second part of the quote refers to milk to treat virus.

[Leafmite]

I have read about milk being used to protect plants against Mosaic virus infection. There have been more recent experiments that have shown it to work, too. Pretty cool. It only works for mosaic but that is the easiest one to transfer between plants so it is pretty significant. Many old-time gardeners were big believers in the power of milk for plants. When I was a kid and collecting plants, I was told that it was good for plants to add milk or powdered milk to my watering can when the plants were outside and in active growth.

[Clawhammer]

I use a butane blowtorch on my cutting shears. It's hard to imagine any virus surviving that.

Sounds like different virus types are resistant to different types of treatment.