wrinkly passionflower leaves
 

Can anyone suggest something to remedy a problem which has arisen with my passionflower? The plant is about 4 years old and has been very vigorous, (over 150 flowers at one time last year). It grows on a sunny south facing wall of the house, and produces fruit. This year the new growth is all wrinkly and bubbly, the foliage is not thickening up as rapidly as usual.