My David Austin 'Blush Noisette' climber, which I planted last year, has bloomed prolifically all year. It has looked particularly healthy until a couple of weeks ago when yellow leaves appeared on one complete central stem. It is planted on a southwest facing wall near the house where it is exposed to quite varied temperatures, from very cold in winter to very hot in summer! My soil tends to be clay but has been mulched often with horse manure and bone meal. Can you give me an indication as to what is wrong and how I can prevent it losing its leaves or worse...dying? Many thanks.
Certified GKH Gardening Expert
This could be caused by any number of things. This article may help narrow it down: https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm