Japanese Lilac - Ask Extension
I have something eating my Lilac that is 2 yrs old. ragged holes in the body of the leaf. In between showers I sprayed with Malathion no effect. Yeste...
Knowledgebase
Japanese Lilac #870591
Asked May 29, 2024, 12:53 PM EDT
I have something eating my Lilac that is 2 yrs old. ragged holes in the body of the leaf. In between showers I sprayed with Malathion no effect. Yesterday (5-28) I sprayed with Triazicide and removed all affected leaves. This morning more holes. Any suggestions? Thanks much
Anoka County Minnesota
Expert Response
Ragged holes are often a sign of slugs. Put out flat boards at night to see if you can trap any:
https://extension.umn.edu/yard-and-garden-insects/slugs
Something that mimics slug damage is hail. Some areas of the Twin Cities have received hail. Did you?
There are a couple of insects which might be the problem. One is leaf cutter bees, although their damage looks more regular than what you have. The damage is only cosmetic and leaf cutter bees are a desirable native:
https://apps.extension.umn.edu/garden/diagnose/insect/garden/flies/medium/leafcutterbee.html
The other is black vine weevil. Again, the damage is cosmetic, although the larvae can damage the root of the lilac. You will have to investigate at night since they are night feeders:
https://ohioline.osu.edu/factsheet/ENT-49
Finally, please don't use pesticides before knowing what the pest is. Pesticides should only be used on the insects on the label and according to the label. The pesticides you used would be ineffective on slugs and would kill leaf cutter bees, a beneficial insect. Remember, the label is the law.
https://extension.umn.edu/yard-and-garden-insects/slugs
Something that mimics slug damage is hail. Some areas of the Twin Cities have received hail. Did you?
There are a couple of insects which might be the problem. One is leaf cutter bees, although their damage looks more regular than what you have. The damage is only cosmetic and leaf cutter bees are a desirable native:
https://apps.extension.umn.edu/garden/diagnose/insect/garden/flies/medium/leafcutterbee.html
The other is black vine weevil. Again, the damage is cosmetic, although the larvae can damage the root of the lilac. You will have to investigate at night since they are night feeders:
https://ohioline.osu.edu/factsheet/ENT-49
Finally, please don't use pesticides before knowing what the pest is. Pesticides should only be used on the insects on the label and according to the label. The pesticides you used would be ineffective on slugs and would kill leaf cutter bees, a beneficial insect. Remember, the label is the law.
