Parti-colored Japanese lilac leaves - Ask Extension
My Japanese Ivory Silk lilac, which I planted about three years ago, has leaves with yellow streaks on one side of the tree (the side closest to a woo...
Knowledgebase
Parti-colored Japanese lilac leaves #871481
Asked June 04, 2024, 10:20 AM EDT
My Japanese Ivory Silk lilac, which I planted about three years ago, has leaves with yellow streaks on one side of the tree (the side closest to a wood fence and on the NE side of the tree). Photos attached. The yellow streaks developed at about the time that the tree leafed out. Leaves on the other side of the tree look fine. Do you know what is causing the discoloration? What should I do about the issue?
Denver County Colorado
Expert Response
Philip
There are several causes of yellow leaves in lilac. In researching your problem, Verticillium Wilt is one that may cause yellowing leaves on certain parts of the bush, rather than the whole bush.
https://ask2.extension.org/kb/faq.php?id=259650
https://hort.extension.wisc.edu/articles/verticillium-wilt-of-trees-and-shrubs/
https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/verticillium-wilt/#management: The appearance of streaking helps to identify the disease but does not guarantee that the tree has Verticillium. Sometimes other factors or diseases cause discoloration of sapwood. Only laboratory examination can positively diagnose the disease. Samples should be sent to a diagnostic laboratory as soon as Verticillium wilt is suspected.
CSU has a plant diagnostic clinic in Denver
https://agsci.colostate.edu/agbio/plantclinic/
there is a page that describes how to submit a sample.
There are other diseases that may affect lilacs. You can read about them here and see if any of the others match what you are seeing in yours:
https://ask2.extension.org/kb/faq.php?id=259650
https://yardandgarden.extension.iastate.edu/article/2021/08/summer-foliar-lilac-diseases
I hope this information is helpful.
There are several causes of yellow leaves in lilac. In researching your problem, Verticillium Wilt is one that may cause yellowing leaves on certain parts of the bush, rather than the whole bush.
https://ask2.extension.org/kb/faq.php?id=259650
https://hort.extension.wisc.edu/articles/verticillium-wilt-of-trees-and-shrubs/
https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/verticillium-wilt/#management: The appearance of streaking helps to identify the disease but does not guarantee that the tree has Verticillium. Sometimes other factors or diseases cause discoloration of sapwood. Only laboratory examination can positively diagnose the disease. Samples should be sent to a diagnostic laboratory as soon as Verticillium wilt is suspected.
CSU has a plant diagnostic clinic in Denver
https://agsci.colostate.edu/agbio/plantclinic/
there is a page that describes how to submit a sample.
There are other diseases that may affect lilacs. You can read about them here and see if any of the others match what you are seeing in yours:
https://ask2.extension.org/kb/faq.php?id=259650
https://yardandgarden.extension.iastate.edu/article/2021/08/summer-foliar-lilac-diseases
I hope this information is helpful.
