It's probably the sticky, syrupy stuff secreted by greenfly. You could spray with insecticide, but not a good idea on fruit that you're going to eat, so give them a strong spray of water from the hose a few times and that should help. If you have blue tits visiting your garden, they'll do a good job of getting rid of the greenfly as well. Have a look on the underside of the leaves, because that's where the greenfly live. Best of luck! The greenfly don't do a lot of harm, but the sticky stuff is unpleasant although harmless to us.
Annie (Cumbria)

im not sure but i would get down the doctors strate away lol x x .