I planted a lilac tree last November. It has plenty of buds but when they turn into leaves, they become dry with holes in them and eventually the leaves die.
New Lilac Tree Leaves Damaged
Certified GKH Gardening Expert
Without a photo, it's hard for me to say what is happening but I can help you narrow it down a little. My best guess would be that your lilac has bacterial blight. Barring that, it could be a leaf spot disease or maybe even lilac leaf miners (any signs of insects?). All of these possibilities are discussed in the following article: https://www.gardeningknowhow.com/ornamental/shrubs/lilac/common-lilac-problems.htm
An extension article on lilac bacterial blight:
An extension article on leaf spot diseases: