How do I get rid of the problem?
Stems and Back of Leaf Covered With a White Insect
Certified GKH Gardening Expert
To me, this sounds like, either a case of aphids, or whiteflies. In either case, You can use rosemary oil, garlic oil, a mixture of Black pepper and water, neem oil, or a small amount of dish soap in water. All of these are excellent methods for general insect control. This article will help futher:https://www.gardeningknowhow.com/special/organic/natural-home-pesticides-organic-garden-pest-control.htm