holly bush leaves have black spots, and are yellow and falling
Why does the above happen? What can we use?
This disease could be something called tar spot. This article will tell you more: https://www.gardeningknowhow.com/ornamental/shrubs/holly/holly-problems-holly-leaf-spot-or-holly-tar-spot.htm
Of course, there are many diseases that can afflict holly, which you might want to be aware of: https://www.gardeningknowhow.com/ornamental/shrubs/holly/diseases-of-holly-bushes-pests-and-diseases-damaging-holly-bushes.htm
To be sure what the problem is you an take some leaves to the Extension Service. This link will help you locate one: https://www.gardeningknowhow.com/extension-search/