Thanks for contacting us about your lilacs. The leaf distortion and “tufting” is consistent with herbicide damage. Herbicides used anywhere near other plants are susceptible to the herbicide volatizing and drifting. Lilacs seem to be particularly susceptible. This amount of damage may not kill the bushes, but will lessen the amount of photosynthesis the plant does to provide nutrients, so it is under significant stress. Give the bushes appropriate water. Avoid further herbicide damage. No need to add fertilizer, which can force new growth but at the expense of the stressed roots – your bushes will need all the stored resources in the roots to come back next spring. These lilacs will benefit from fall/winter watering when the irrigation systems are turned off. See the links below for details.

Any twigs that become brittle can be removed, but keep any flexible twigs – it’s a sign of life!

• Nebraska Forest Service Herbicide Damage: https://nfs.unl.edu/publications/herbicide-damage-trees
• Utah State University Herbicide Injury: https://extension.usu.edu/planthealth/ipm/notes_orn/list-flowers/herbicide-injury
• Colorado State University Fall and Winter Watering: https://extension.colostate.edu/docs/pubs/garden/07211.pdf