Your foliage looks good, Suzy. If you have time and want to continue washing the foliage, inspecting for the saw fly larvae, and you don't have many plants, you may not need any "products."

If you have many plants; if you find washing the foliage and inspecting for the saw fly tedious or too energy and time consuming and you don't mind using products to control or eliminate the insect issues, by all means use them. If you only have a few plants and enjoy manually attacking the insect issues, then continue doing that. Whichever is most enjoyable and reasonable for you is valid.

That white leaf will probably never turn green. Whether it is a genetic mutation or caused by a virus, when it was formed, something prevented it from forming the ability to produce chlorophyll. It likely isn't capable of turning green. If it offends you, clip that one off. It won't hurt anything to leave it or remove it. Only green parts photosynthesize food. You have probably seen the cactus and succulents in red or yellow which have been grafted on to green plants to create decorative potted plants. The other colors are not capable of "feeding" themselves through photosynthesis, so they are grafted on green plant parts which do generate food. That leaf is likely similar to the other colored cacti and succulents. If it bothers you, remove it. If it doesn't, leave it alone. It probably won't make any difference either way. And, I seriously doubt it is anything to worry about nor anything you can prevent occurring again. If it is a mutation, it might or might not happen again. If it is viral, it may, or may not reoccur, but there still isn't anything you can do about it and it won't "spread" to other plants unless you bud or graft pieces of this plant on to the others.

Just keep feeding and watering the plant as you have and it should continue performing as it has for you. Have fun! Thanks. Kim

If when the plant matures and you decide to spray for sawfly larvae someday you may want to spot test it first.
Spray just a small portion of the bush in case the leaves of that certain rose are sensitive to the spray.

That's good advice for spraying any plant, with any product. Some are more sensitive to different types of sprays than others. Some don't seem to be sensitive at all, like some people have "elephant skin" where nothing bothers them, while others react to everything. Kim

Thank you both. Good advise. I can wash the leaves. I have two trees and a mum beside the rosé bush. Do you cut down fertilizer if you have the bush inside in winter like you do for citrus?