Some of my fuschias have developed very pale yellow, almost white leaves, which appear crinkled. Only the top half of the plant is affected. The rest of the leaves are dark green and healthy looking I have a number of fuschias of different varieties, but only one type is affected. They are in large adjacent pots in my south facing garden in the NW of England, near Manchester. I can see no sign of insect damage, or any other infection. The pots are treated every 6 months with vine weevil killer, as advised by a professional TV gardener. In October I always cut the plants back and bring them into my unheated conservatory, attached to the back of the house. The affected plants have been like this for about 3 years now. They start growing healthily in the conservatory, but as soon as I put them outside in late may the probelm starts.

Any suggestions??