I have just noticed that my long established wisteria has developed yellow patches/spots with tiny black lines/eggs(?) in the middle, on many of its leaves. I would be very grateful if you could identify what these are and what the recommended treatment would be. Thank you!
This could either be from a fungus or insect pests. I would treat the vine with neem oil, which will take care of both issues just to be safe. Here is more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm