River birch - potential aphids? - Ask Extension
Hi there,
We have a river birch that was planted last summer, so first time through the spring for us. It's developed some sort of infection or paras...
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River birch - potential aphids? #832911
Asked May 31, 2023, 11:17 AM EDT
Hi there,
We have a river birch that was planted last summer, so first time through the spring for us. It's developed some sort of infection or parasite on some of the leaves. What looks to match some images I've seen of aphids (witch hazel?) and the 'ruffling' of the leaves. I've attached a few photos, would really appreciate a more expert appraisal. And importantly, what (if anything) we should do, or if we just let it take its course (which is what I saw from some light googling).
Thanks so much!!!
David
Montgomery County Maryland
Expert Response
This is a fairly common type of damage caused by Witchhazel Aphids, either Spiny Witchhazel Gall Aphid or Witchhazel Cone Gall Aphid (they are very similar and have essentially the same life cycle). The aphids create leaf galls - the crinkly distortions of the leaves - as a result of their feeding. They are native insects and the damage they do tends to be apparent at this time of year but it does not last all season.
Fortunately, nothing needs to be done about them. There are many natural predators that consume aphids, so the use of an insecticide is not necessary (and would potentially kill the beneficial insects you want working on the aphids). You can learn more on this page published by Ohio State University.
Since your tree was just planted last summer, make sure to keep up with watering to help it establish a good healthy root system. It has been abnormally dry in central Maryland. A light layer of mulch around the base of the tree will help to retain soil moisture and prevent mower injuries to the trunk. Place the mulch so that it is no more than about 3" deep and not directly in contact with the trunk.
Feel free to reach out again if you have additional questions.
Christa
Fortunately, nothing needs to be done about them. There are many natural predators that consume aphids, so the use of an insecticide is not necessary (and would potentially kill the beneficial insects you want working on the aphids). You can learn more on this page published by Ohio State University.
Since your tree was just planted last summer, make sure to keep up with watering to help it establish a good healthy root system. It has been abnormally dry in central Maryland. A light layer of mulch around the base of the tree will help to retain soil moisture and prevent mower injuries to the trunk. Place the mulch so that it is no more than about 3" deep and not directly in contact with the trunk.
Feel free to reach out again if you have additional questions.
Christa
