We recently purchased a house and inherited a beautiful perennial garden that includes two beautiful Lilac trees and three small cherry trees. The previous owners paid a service to come annually to treat these trees against foliar diseases as well as a series of nutrient treatments. The Lilacs survived a bit of blight last fall. However with the high cost, we wondering how necessary these treatments are or if perhaps there DIY options to achieve the same results. We love our plants and would hate to jeopardize their health. Thanks in advance for your help.