Pansy has white leaves.

Hi!I have quite few planters filled with winter pansy but some of them has white something on their leaves.Tried to spray it few times with green spray for bugs and disease but does not work.Also the plants which are affected are much smaller then the other so definitely there is something wrong with my plants.can i buy something to treat them?

 

Has the white been on the leaves all the time? Apart from fungal infections leaf scorch can cause white marks, if they had been watered in sunlight while they were under glass, if they had wilted badly before you got them.