Hi Hunter!

Your lilac has a heavy infestation of White Prunicola Scale, small, soft-bodied insects covered by a waxy protective shell. The third generation of this scale is about to hatch, so you will want to decide quickly on a treatment approach. Here are a few options to consider:

Option 1 - Drastically cut the plant back close to the ground. The benefits of this route include an immediate reduction in pest population and it avoids using chemicals treatments. The downside is that there will be no blooms for the next few years as it regrows, but it is the simplest approach to managing this heavy of an outbreak. 

Option 2 - Using a scrub brush, rub off what scale you can from the lilac. Treat with horticultural oil (a guide to this can be found on our scale management guide).

Option 3 - Use chemical control on the infestation by hiring a professional pesticide applicator. 

Option 4 - Remove and replace the entire plant. This prevents the use of chemical insecticides and repeat management efforts, which could be time consuming and costly, as this heavy of an infestation may require a licensed pesticide applicator to step in. 

Jamie