The new Whitebeam leaves look lovely especially when they flutter in the breeze & show their lighter underside. But every year I see discoloured bumps in leaves (here on lower left), doesn't greatly affect growth but I'm curious. Is it fungal or viral disease, anyone know?
It's caused by a gall mite Alex there is not much you can do to get rid of it apart from picking off the affected leaves if the infestation is light . It doesn't tend to harm the tree
The new Whitebeam leaves look lovely especially when they flutter in the breeze & show their lighter underside. But every year I see discoloured bumps in leaves (here on lower left), doesn't greatly affect growth but I'm curious. Is it fungal or viral disease, anyone know?
It's caused by a gall mite Alex there is not much you can do to get rid of it apart from picking off the affected leaves if the infestation is light . It doesn't tend to harm the tree