My Pothos has white grainy gravel-like exudate on the underside of the leaves. Is this something I need to be concerned about? The plant looks healthy but the underpart of the leaves looks as if someone splashed milk on the underside of the leaves.
Pothos Has White Grainy Gravel-Like Stuff on Underside of Leaves
Certified GKH Gardening Expert
Without seeing the substance I would be on the cautious side and treat with Neem Oil.
Neem Oil works as both an insecticide and fungicide and is safe for people and pets.
If this is a newly purchased plant it is likely it is a residue from watering, fertilizer and pest control from the greenhouse grower.
It could be just wiped away with a damp, soft cloth.
Here is a link with more information.