Q.Black soot on rhodendrons, pirrus and azalea
We have a thick black covering on nearly all of our rhodendrons, pirrus and azalea – and we have a large woodland garden so it is a physically huge problem.
I cannot possibly wash all the plants, it would take me years!!
I need a spray to treat the pests that are causing this problem, but i need a lot of it. Could you advise me what to do please.
This can be difficult, as there could be multiple pests. My best recommendation would be to apply a broad spectrum pesticide. This can be something as simple as a garlic spray, rosemary oil, or pepper extract. This collection of articles will help you to craft your own pesticides, among other organic gardening tips: https://www.gardeningknowhow.com/special/organic/