Scale infestation? If so, how bad?
I've had this euphorbia for well over 10 years, and always assumed the brown/tan formation was a sign of age. But I also noticed some other plants in my home having some growth on them. I've attached a picture. Across the top is the stem of a dracaena deremensis, under it to the right is the euphorbia, on the left is a dieffenbachia (the cane on top, back of leaf on bottom). Is this scale? If so, how bad is it and can it be cured? If not, what is it? Thank you.