I have four lilac bushes (small, not sure what variety...they came with the house). They are all in different areas of my yard, not all together. They budded and some of the buds (but not many) have flowered. I noticed there is a lot of new growth but the majority of leaves on each bush are shriveled and the tips are browning/black. I am really confused as to what is causing this. Is this a fungus/disease or could this be due to frostbite? I kinda ruled out frost because my neighbors lilac tree is beautiful and FULL of flowers. But it did warm up here (SE WI)and then got cold again but I'm not sure that we actually got frost. Any ideas?