Hi, I have a few tomato plants exhibiting stunted, twisted growth, interval chlorosis, purple tinge to leaf undersides, upwards curl to leaf edges and on older/earlier affected leaves black spots (not necrosis) on the underside where chlorosis is occurring. Nutrient concentration is about 1,800us, pH 6.2. I suspect I have fallen victim to a virus of some sort. If this is the case I understand the plants are lost and need to be removed. My question is, what do I need to do to decontaminate the room and equipment?

By Eric Hopper | Last updated: December 14, 2021

Thank you for your question. When a plant gets infected by a virus it should be immediately removed from the rest of the crop to avoid further contamination. If all plants have fallen victim to a virus, a grower has two options. The first is to allow the plants to finish the cycle and hopefully salvage a harvest. The second is remove the entire crop and start over. With either choice, a decontamination of the room and equipment is absolutely necessary to avoid reoccurrence.

The simplest and most effective way to sterilize a garden space is with a diluted bleach solution. The percentage of bleach in water should be about 10 per cent for this purpose. In other words, mix nine parts water to one-part bleach. This solution can be used to wipe down walls, planting containers and hydroponic systems. Scissors, trellis netting, and anything else that came in contact with the plants will need to be sterilized as well. After wiping the equipment with the bleach solution, it is a good idea to rinse the equipment with pure water; especially any items that come in direct contact with the plant’s roots or medium (hydroponic systems, reservoirs, planting containers, etc.).

Rinsing is important because bleach can leave a residue behind that can be harmful to plants. This is why many growers will choose to sterilize with hydrogen peroxide instead of bleach. Unlike bleach, hydrogen peroxide will not leave a residue behind, but instead becomes water after oxidization occurs. Higher concentrations of hydrogen peroxide (35 per cent) should be diluted to a one-part peroxide, one-part water solution. Whether you use bleach or hydrogen peroxide, make sure to wear proper safety equipment during the decontamination process. Rubber gloves, respirators, and eye protection are all crucial when using strong solvents.

To avoid this problem in the future, do not use equipment that has been used elsewhere in the indoor garden. Viruses are generally brought in by an unsuspecting gardener who shares equipment with an outdoor garden. Viruses can also be brought in on the hands or clothing of the grower or a vector pest insect. A quick hand-washing and change of clothes before entering an indoor garden or greenhouse is a great way to reduce the likelihood of introducing plant viruses or other pathogens.

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Grow Spaces Cleanup and Sanitation Plant Disease Plant Health

Written by Eric Hopper | Writer, Consultant, Product Tester

Profile Picture of Eric Hopper

Eric Hopper’s past experiences within the indoor gardening industry include being a hydroponic retail store manager and owner. Currently, he works as a writer, consultant and product tester for various indoor horticulture companies. His inquisitive nature keeps him busy seeking new technologies and methods that could help maximize a garden’s performance.

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