Hello,
The leaves on my raspberry plants have started to turn a very bright yellow - but only in patches. Many of the plants maintain a vigorous green leaf. Fruit growing on both yellow and green areas appears the same and OK. These are late summer/autumn raspberries. they were well mulched with rotted stable manure in April. ome were transplanted to other areas of my allotment, thesae are also yellow. June fruiting raspberries alongside are completely unaffected.

Any ideas/help please?
I am an organic gardener