A Conversation about Whats with the Lilacs

Lilacs are about the best known shrubs in the American landscape. They aren't native, but have been grown in gardens since about 1750. The common lilac (Syringa vulgaris) is most familiar, and we often inherit one when we buy an old farmhouse. They are famously long-lived, and are a frequent subject of stories and poems. The poet Walt Whitman wrote the classic “When Lilacs last in the Dooryard Bloomed” as an elegy to Abraham Lincoln following his assassination in 1865. The lilac is embedded in our American history as a symbol of prosperity and the common good.  They have always been nearly indestructible, lasting in abandoned farmyards for decades. So what's happening now? Panic!

Our lilacs are dropping leaves like it's December, and what I call “panic blossoms” are appearing.

Don't despair if your ancient lilacs are turning ugly. The cause is a confluence of weather conditions. Last year there were many sightings of what I call “Panic Blossoms” from the lilacs. It's kind of an urge to reproduce when they are stressed, even out of season.
Climate change has resulted in conditions that are wildly welcoming to the bad guys. Last year's drought stressed the plants, so you would think the excessively wet spring made things balance out. Unfortunately, early wet weather is inviting to many fungus diseases. Even more unfortunately, this year's wet start was followed by drought... but humidity remained high, so the fungi had a field day, or summer, if you will. The leaves shriveled up and dropped off, making the shrubs look dead. By the way, at the same time, maples and crab apples were having the same problem. The sort of good news is that it's happening late enough in the year that the plants should recover in the spring. In fact, my oldest lilac is already starting new foliage along with her panic blossoms. The newer hybrids seem less susceptible, but it may just be their comparative youth. The elderly lilac by the house is probably at least seventy years old. Fred Breglia of the Landis Arboretum explains it better in a Times Union interview, at https://www.timesunion.com/news/article/despite-falling-leaves-distressing-fungus-trees-20815944.php

It never hurts to invest a little effort into helping the recovery along, though. Trimming old branches  and encouraging the suckers that look healthiest, along with some attention to the soil quality, when the defoliation makes it easier to see the “bones” of the plant, can give the plant a better chance to revive. If possible, water at root level when drought conditions occur. Lilacs like a mildly acid soil, so unless the soil tests at an extreme of either acid or alkaline pH, an all purpose fertilizer will help, applied at recommended rates, and top dressing with compost is always welcome for a longer, slower soil improvement. There are many hybrids available, and many colors. There are repeat blooming varieties, and Korean hybrids that bloom later and with smaller foliage and blooms, but the scent is as good. Some are disease resistant as well, so shop around for some variety if you want a change. Your county's Cooperative Extension Master Gardeners can help with questions about plant diseases and pH, and there's usually a phone or online hot line available.

If you have any comments or suggestions for future columns, contact me at jeanthepipper@duck.com.