The peach leaf curl is a fungal disease caused by Taphrina deformans.
The name describes very well the damage this disease causes to the leaves. It mainly affects peach trees, but also other fruit trees such as almond, apricot, plum, and cherry trees.
This fungus prefers cool temperatures and humid conditions, which is why it thrives in spring, especially in April, particularly when it rains. It withstands winter cold by sheltering under the bark, while in summer, when temperatures are high, it loses much of its aggressiveness.
It is not a disease that appears every year, because it is closely linked to weather conditions, but it can weaken the plant for the following seasons and significantly reduce the harvest.