Hollies can usually recover from leaf spot.
The leaves of my newly-planted ‘Carissa’ hollies are covered in black spots. What should I do? Will this do long-term damage to my hollies? – Nikki
It sounds like your holly plants have been infected with a fungal disease known as holly leaf spot, sometimes called holly tar spot. It can be caused by several different fungi, but the symptoms are similar: the leaves develop black, brown, or yellow spots. Eventually, the infected leaves fall off the plant, leaving your holly bare and spindly. Leaf spot usually develops during wet spring weather, and the leaves begin dropping throughout the summer and fall.