If the currant leaves have changed, there may be two reasons.
The first is a pest attack.
Most often, red blister-like spots in the form of swellings appear if the bushes have been attacked by gall aphids.
It is important to understand that aphids are dangerous pests that can quickly destroy crops and plants. Therefore, you should immediately treat the plants with an insecticide.
Another way is to wash the aphids off the back of the leaves with a sharp stream of water from a hose. In this case, you can get rid of most of the insects.
The second reason for leaf changes is a fungus (anthracnose).
In this case, small brown-red spots appear. But not only the leaves suffer, but also the fruits. As summer residents note, small light-brown spots with a red border can be seen on the berries.
The problem can be dealt with by spraying with a special preparation.