A reason for bloom failure is too much fertilizer. Another reason for bloom failure is pruning in fall. Lilacs set blooms the year before. It also looks like some leaf puckering. Could there have been some herbicide drift to the leaves? Finally one of the most common disease of Tree lilacs is blight. The following websites give information on what to look for. You can also send a sample to the Plant disease clinic if you would like confirmation of a disease. The last website gives signs of other lilac tree diseases that are also possibilities. If you don’t see signs of diseases such as blight, it will probably be okay and bloom next year. 1. https://hortnews.extension.iastate.edu/lilac-bacterial-blight 2. http://hyg.ipm.illinois.edu/article.php?id=166 3. https://pdc.umn.edu/submit-sample 4. https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/japanesetreelilac/index.htmlhttps://apps.extension.umn.edu/garden/diagnose/plant/deciduous/japanesetreelilac/index.html

I was wondering how much it would cost to bring in a few branches of my Japanese Lilac tree to see if it has any disease?  Also, can I bring the sample in person?  I understand that I probably won't be able to see anyone due to Covid19.  However, if it is possible to see someone in person, please let me know.  Otherwise, I would just drop off the branches and payment in person.
Thank you.

The Plant disease clinic is currently locked. If you were to bring a sample you would need to make arrangements ahead of time. The phone number is: tel:<personal data hidden>. The fee schedule is explained in the second website. 1. https://pdc.umn.edu/submit-sample 2. https://pdc.umn.edu/services-fees