I grow amaryllis too.
As for it's effectiveness on plants, I doubt it will do much harm or good for that matter. Someone correct me but a virus in a plant will be spread via juice of that plant, pollen and other means such as shared water. Topically spraying doesn't seem like it would do much good but sterilize the surface, when the illness is under that surface. Also, plant viruses only die when the plant is destroyed. It will never be cured of it like an animal can.
Just my thoughts but I could be very wrong here.
Sent from my iPhone using Tapatalk