ANY UPDATES TO QUERY# 884305?  LILACS DROPPING ALL LEAVES TOO EARLY, AFTER WILTING AND TURNING BROWN.

Question: Hello, Our property is surrounded by Lilacs on three sides. In late August we noticed that the leaves are unexpectedly dropping and /or are shriveling up and turning brown before dropping.  These lilac bushes have been here for 40 years and i have never seen anything like this,  All other bushes on the property seem fine...green and healthy.  I have noticed the same condition on lilacs on other peoples property.  Can you help explain what is causing this?  Are the lilac bushes dying for some reason?

responder: Thank you for contacting the Infoline, a service of UNH Cooperative Extension.Danielle Albano Education Center Volunteer Program ManagerUNH Cooperative Extension Education Center Replied September 09, 2024, 10:33 AM EDT
response: Hi Dennis, Thank you for contacting the UNH Extension Infoline and thank you for your patience in our reply here. Your lilac-related questions have been a very popular question with our Infoline clients! We've been in communication with other coworkers regarding these symptoms as we've received a high quantity of calls/emails over the last 2 weeks.It is difficult to clearly identify the problem as one sole cause, but based on how some of the leaves appear to have brown spots it is possible that the lilacs have Lilac Bacterial Blight. This is a useful resource for this: http://plantclinic.cornell.edu/factsheets/lilacbacterialblight.pdf Make sure that if you fertilize your lilacs, don’t overfertilize and stop fertilizing all together around mid-summer because elevated levels of nitrogen in the soil can lead to more favorable conditions for the disease. We recommend testing the soil to check the pH and nutrient balance. The UNH Extension also has these services for $20 per test and you can find the form here. Infected branches should be pruned 10-12 inches below the visible infection as soon as you see indications of disease. Pruning should be done during dry weather to minimize the chance of spreading the pathogen and if you are pruning your bushes late in the summer, make as few cuts as possible. The act of pruning sends a signal to the plant to grow and at this time of the year that can lead winter damage on tender new shoots. Pruned branches should be destroyed, ideally by burning. Always sterilize pruning tools between cuts to prevent spreading the bacterium to other areas on the tree. You could also submit a sample to the UNH Extension Plant Diagnostic Lab for $20 to get a more definitive determination of the issue and ways to treat it. The submission form with directions is found here.We hope this information gets you in the correct direction! Please reach out if you have any further questions.

responder: Thank you for contacting the Infoline, a service of UNH Cooperative Extension.Danielle Albano Education Center Volunteer Program ManagerUNH Cooperative Extension Education Center Replied September 18, 2024, 10:51 AM EDT
response: Hi Dennis,Thank you so much for your follow up message here. We have been reaching out to the plant diagnostic lab on our end and they are still conducting research to see what the cause(s) may be and the best management steps moving forward. I apologize but we do not have any more information just yet at the Education Center. As soon as we have more information, a blog post will be published from UNH Extension.On the plant diagnostic lab webpage, here is their direct contact information: email: <personal data hidden>, phone number: <personal data hidden>.Thank you and we all hope that we can resolve this common issue for NH clients soon!

responder: The Question Asker Replied October 07, 2024, 8:19 AM EDT
response: I HAVE ALREADY SUBMITTED INQUIRY #884305. I HAVE NOT SEEN ANY UPDATED INFO FROM UNH ON WHAT IS CAUSING THIS LILAC CONDITION. I WOULD LIKE TO KNOW IF THE PLANTS WILL STILL BLOOM NEXT SPRING OR DO I HAVE TO SEVERLY CUT DOWN AND CUT BACK MY TALL LILAC BUSHES?

responder: Steph Sosinski  Replied October 10, 2024, 5:17 PM EDT
response: Hi Dennis, thank you for following up again.  Leaf spot disease symptoms can often look similar, so without submitting a fresh leaf sample into our plant diagnostic lab, it is very difficult to accurately diagnose. However, that being said, our diagnostic lab has updated us with a few different pathogens that they were able to identify from other samples sent in the last two months. Those include: bacterial blight (Pseudomonas syringae,) and fungal pathogens including: Anthracnose (Colletotrichum sp.,) and leaf spot (Cladosporium sp.) All of these cause leaf spot and blight symptoms. To test the presence of bacteria vs. fungi, one fairly simple test anyone can conduct at home is to cut a few symptomatic young stems and place in water. Fairly quickly, if you see ooze streaming from the stem and into the water, this indicates a bacterial pathogen, and if you don't, it is fairly safe to say it's fungal instead. Other symptoms of bacterial blight are drooping and browning shoots and stem tips (called a shepherd's crook,) black streaking on stems, and in severe cases, cankers. Regardless of the specific pathogen, all of these are rarely lethal diseases that can typically be managed without chemicals, unless infection and defoliation reoccurs in multiple years, especially with other environmental stresses (e.g., drought, winter damage, excess moisture.) A primary method of disease prevention is good sanitation, and something you can do now: collect and destroy all of the fallen leaves and debris from your lilacs, as this is the major source for spores to overwinter and be available to reinfect next year. Additionally, renewal pruning can help to increase airflow in the canopy and between shrubs; lilacs grown in shade and closely together are more susceptible overall to disease spread given the reduction in light and airflow. Renewal pruning can be done in early spring before budbreak or immediately after blooms in the early summer, by cutting back 1/3 of the oldest stems down to the ground. Pruning diseased or dead branches can be done anytime of the year (although not in excess during fall or winter, as this can lead an increased risk of winter damage.)  Ensure pruning occurs during dry weather, and with sanitized tools (use 10% bleach solution or rubbing alcohol.) These are some excellent, comprehensive guides that provide more detailed information on lilac diseases and management: University of Maryland Extension: https://extension.umd.edu/resource/lilac-identify-and-manage-problems/ University of Minnesota Extension: https://extension.umn.edu/plant-diseases/lilac-issues-and-diseases