Q What are these black marks on my walnut fruits and leaves?
A Dark marks on the fruits can be caused by physical damage, such as heavy winds. The most common cause of leaf deformity is leaf gall, which causes raised lumps on the leaf undersides. There’s also an anthracnose disease that causes black marks on the leaves but it rarely affects the fruits. What’s more, it’s most common in wet weather, so it’s unlikely to be a problem this summer!