Question: Two lilac trees on my property have some disease or pesticide infestation. Can you help me identify the problem and offer a solution?  Answer: Jonathan Foster, Home Horticulture Outreach Professional Lilacs commonly suffer foliage fungal infestations, especially in hot, wet summers, and it definitely looks as though that’s what’s going on here. Typically, they read more Can you help identify the problem with the lilacs on my property?