COVID-19, Disinfectant and Plants

Ever since the COVID-19 outbreak, I’ve come across a few damaging plant situations.  One of the first problems was overwatering and root rot when my clients had their staff maintain the plants during my absence.  Yellowing leaves, soft stems, soaking wet soil, while a real pain to fix, was at least fairly easy to diagnose. 

The second damaging situation I’ve encountered is reduced light levels.  Even the low-light tolerant plants were struggling with many brown tips.  As soon as I walked towards them, I realized the overhead lights were on a sensor.  I never realized the hallways had energy saving devices before since the lights were previously on constantly. 

Now, with most staff working from home, the lights are off for most of the day. Conference rooms, boardrooms, offices going unused for months have been bad light situations for the plants. Moving the containers to areas with windows or under lights that are required to remain on, has alleviated most of this problem. 

This last bit of plant damage I encountered had me much more perplexed.  Inside this beautiful three-story atrium, there was a large section of pothos and aglaonemas that had yellowed with black spots.  It almost appeared if they were suffering from root rot mixed with someone taking a lighter to the leaves.  

It couldn’t be a lack of light since the entire roof was glass and acted like a greenhouse.  The soil wasn’t wet, it was even a little dry so it wasn’t saturated soil killing the roots.  Since it only seemed to be affecting one area, I thought someone may have poured some leftover cleaning solution in those planters.  There was only one housekeeper in charge of the entire building and after five years of working with her, I knew she wouldn’t dump any liquids in the soil.  

A few years ago, I had seen something similar to this damage at another location.  The pothos vines along the in-ground planter started to turn the same funky yellow with black spots.  The damage was prevalent along the edge. When I brought this up to the facility manager, he said their pesticide vendor had recently sprayed around the edges.  Luckily, after removing the damaged foliage, the pothos recovered and filled back in.

Then I recalled a conversation with this building manager about the extremely expensive quotes he was getting for a COVID sanitizer application for the building. At the time, it didn’t concern me that it may affect the foliage. When I worked at a commercial greenhouse, the person applying the pesticides had to wear a hazmat suit, apply at night and no one could enter the greenhouse for twelve hours after.  Could a simple disinfectant do this much damage to plants which are resistant to extremely toxic chemicals? 

Not wanting to blame another company when I had no proof, I showed the manager the damage, mentioned the similar situation at my other client’s location and thought once I remove the damaged foliage, the vines would recover.  The next couple weeks, the burning got worse and started turning the neathebella palm fronds black.  If this wasn’t figured out quickly, there could be thousands in Kentia palms and other foliage destroyed. 

This time, the manager emailed me the chemical components of the disinfectant which I forwarded to my pesticide expert. On the surface, it sounded very safe as far as chemicals go. The only harmful side effect to humans were mild skin irritants.  

My chemical expert explained to me that there were two compounds, sodium chloride (salt) and silver ions, that were likely affecting the plants.

When combined, this heavy salt mixture will burst open any living cell it comes in contact with and then burn the insides. Since a chemical can’t distinguish the difference between bacteria cells, plant cells or human cells, it burns everything it touches.  

If you are noticing leaves that are turning pale, crispy with black patches, most likely it’s due to a new sanitizing service that is becoming popular to mitigate COVID-19 transmission. Fortunately, my client had their sanitizing company change their formula to something that is more plant friendly.  So far, the plant cell destruction appears to have stopped.

Luckily, these particular plant problems have been salvageable for the most part. However, keeping communication lines open with building contacts is key when diagnosing especially unusual plant problems, as they have insight into other potential causes for issues.

Sherry has been part of the interiorscape industry for over fifteen years, starting at an entry level job at North Florida's largest greenhouse and currently owning two horticulture companies. At UMaine, Sherry majored in English where she worked part-time writing scripts for a local college TV studio.

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