Hi!
I've had a philodendron tiger tooth for several months and I recently lifted one of the leaves and came across a sticky substance on the bottom (I actually purchased the plant during a sale one of my favorite shops was having, so the leaves already had some signs of previous damage due to pests, etc).
Anyway, I did some googling and it said that it could be honeydew caused by a scale infection. I have several other philodendrons that have that same sticky substance on top and underneath the leaves, but when I look closely, I'm not seeing anything (there were 2 that I watered yesterday that had the same issue). I do spray my plants with that Capt Jacks X-Mite or an insecticidal soap everytime I water them, as well as use the systemic granules.
The plant I'm writing about has not been exposed to any other new plants. Also, I did water it about a week ago. Any ideas?
Thanks so much!