My Lilacs are dying

Question: My lilacs have turned brown and shriveled up.  I just noticed this when my husband questioned it.  They are about 50 years old.  Very tall. Did.not bloom well this year. I hope it is not blight. At my age it is difficult to get out and trim 12 huge trees.  Enclosed are some photos.

responder: An Ask Extension Expert Replied August 19, 2024, 11:17 AM EDT
response: Thanks for your question. In most years, lilacs tend to be relatively disease free. When sited properly (in full sun) and pruned/thinned regularly, they reliably produce a bounty of beautiful blooms each spring. Some possible causes for your lilacs to be browning:   1). Bacterial blight. Among other things, blight is characterized by leaf spots that can lead to leaf darkening, leaf wilting, and premature leaf dropping. Fortunately, this is largely a cosmetic condition and unless it occurs over several seasons, there are no adverse effects. It is associated with wet conditions, which certainly describes our current 2024 season. This is NOT a fungal pathogen; application of fungicides will do no good. It can be transmitted from one season to the next via leaf debris. To prevent transmission from one season to the next, thorough fall cleanup is essential. To help avoid lilac blight, don’t fertilize late in the growing season and don’t over fertilize young plants because high nitrogen favors disease development  When planting lilacs, provide adequate spacing between shrubs. Thin individual shrubs each winter to promote good air circulation. Properly water, fertilize and mulch shrubs to avoid  stress that may predispose them to disease. Avoid overhead watering that may keep leaves wet. Many deciduous shrubs (those that lose their leaves in the fall) can be kept healthy and vigorous by removing a few of the largest, oldest stems every 2 or 3 years. Neglecting to do this can cause shrubs to  become leggy and unattractive. Flowering shrubs that are not pruned properly may not bloom well.  2). Cercospora or Septoria fungal disease. The symptoms are small, brown to black spots appearing on lilac leaves. The distinguishing feature of these spots is that they are surrounded by a yellow halo. Inspect your lilac leaves to see if this halo is present. The leaves will also become distorted and drop prematurely.   These diseases are weather-dependent and require wet, humid weather when new leaves are developing to flourish. Symptoms usually present late enough in the season that damage to the plant is negligible. Therefore, we usually do not recommend a fungicide application as the overall health of an otherwise healthy lilac will not be impacted. However, we do recommend raking up and composting or discarding diseases leaves to reduce disease inoculum the following year. Environmental conditions, humidity, and stressors like drought, shaded locations, or lack of proper pruning could be encouraging development of these diseases.   There is not much you can presently do to make your lilacs attain a normal appearance. The most important thing to do now is to rake up and destroy the fallen infected leaves. This will help prevent the bacterial pathogens causing the disease from overwintering and re-infecting your lilac next year.   Besides cleaning up and removing all leaf debris at this time, you could remove a few stems of the oldest stems of each of your lilacs (up to 1/3 of the stems) just above ground level to open things up. The objective is to improve air movement and circulation throughout the bush. This will help in decreasing the spread of the disease and can be done every year. And be sure your lilacs are not watered by overhead sprinklers. The link below will provide some additional information.  https://www.purduelandscapereport.org/article/lamentable-lilac-leaf-diseases/

responder: The Question Asker Replied August 19, 2024, 1:13 PM EDT
response: Thank you,  I am thinking since this is the  first time this has happened it is probably all the rain we keep getting.  Will do some trimming and get rid of all the leaves on the ground... THanks again.RebeccaRebecca Case <personal data hidden>On Mon, Aug 19, 2024 at 11:17 AM Ask Extension <<personal data hidden>> wrote: