My Basil Plants Have a Disease or Insect Problem

Question

They have a white scale on their stems and white pustules that ooze a white milky substance. The leaves are starting to look yellowish and not a healthy green.

Answer 1

It sounds like mealybugs. This article will help:
https://www.gardeningknowhow.com/plant-problems/pests/mealybugs-white-residue-on-plants-leaves.htm