Answer: What you describe sounds like Psuedomonas syringiae, or bacterial lilac blight. To control, prune the affected shoots back about 12" below the infected leaves. This should encourage healthy new growth. When new growth begins, feed your lilacs with a 5-10-10 or 10-20-20 and be sure to water them deeply once each week. Feeding and regular watering will help your lilacs become more robust and less likely to develop problems. Good luck with your lilacs.
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