Stressed Young River Birch - Ask Extension
Hello,
One of our tree recipients received a Heritage river birch from our program: Betula nigra 'Cully'
The tree came from the nursery in November...
Knowledgebase
Stressed Young River Birch #873522
Asked June 17, 2024, 6:31 PM EDT
Hello,
One of our tree recipients received a Heritage river birch from our program: Betula nigra 'Cully'
The tree came from the nursery in November 2023 and planted in December 2024. This is the first time we are seeing it leafed out. The leaves are small, cupped, and have brown edges. The tree is being correctly watered once per week. The new growth is minimal.
When inspecting the leaves, I also noticed a lot of white webbing around the leaves - I little more cottonlike than a traditional spider web.
I'm told landscapers used round up nearby, but they said they did not broadcast spray and it was not windy they day they sprayed.
Do you know what we might be looking at?
Multnomah County Oregon
Expert Response
Hi Molly and thanks for your question and pictures of your River Birch trees. I'm pretty sure the webbing is spider mites, but I'm not sure if the damage to the leaves is caused by them or is the reason they moved in.
The trees look quite stressed and I'm wondering if they are planted correctly. The leaves look drought stressed and their seems to be a lot of wood chips around where they are planted. Could the chips be so deep the trees are not getting the water or could they be decomposing and taking the nitrogen out of the soil where the roots are? This happens if the chips have been mixed with the soil when the trees were planted.
This species is also not salt tolerant and the leaves match the symptoms for scorch, which relates to plants not getting a certain nutrient when they are growing rapidly. The leaves also match the symptoms for herbicide spray, so don't rule out that possibility, whatever the landscapers said.
So there are a couple of things I would suggest. You really need a soil test to see if there could be something in the soil affecting the trees. Here is a connection to a local lab that does soil testing: https://al-labs-west.com/soil-analysis/
To get rid of the mites, a spray of insecticidal soap on the leaves should help. You can also try a couple of teaspoons of detergent in a quart of water if that is easier. If the mites are not the original problem, getting rid of them will at least help the tree recover if it gets the chance.
And lastly, you could have an ISA certified arborist come out and look at them. They should not charge you just to look, but get several opinions so you can see if they agree.
https://www.treesaregood.org/findanarborist
Keep playing detective to figure out this problem.
The trees look quite stressed and I'm wondering if they are planted correctly. The leaves look drought stressed and their seems to be a lot of wood chips around where they are planted. Could the chips be so deep the trees are not getting the water or could they be decomposing and taking the nitrogen out of the soil where the roots are? This happens if the chips have been mixed with the soil when the trees were planted.
This species is also not salt tolerant and the leaves match the symptoms for scorch, which relates to plants not getting a certain nutrient when they are growing rapidly. The leaves also match the symptoms for herbicide spray, so don't rule out that possibility, whatever the landscapers said.
So there are a couple of things I would suggest. You really need a soil test to see if there could be something in the soil affecting the trees. Here is a connection to a local lab that does soil testing: https://al-labs-west.com/soil-analysis/
To get rid of the mites, a spray of insecticidal soap on the leaves should help. You can also try a couple of teaspoons of detergent in a quart of water if that is easier. If the mites are not the original problem, getting rid of them will at least help the tree recover if it gets the chance.
And lastly, you could have an ISA certified arborist come out and look at them. They should not charge you just to look, but get several opinions so you can see if they agree.
https://www.treesaregood.org/findanarborist
Keep playing detective to figure out this problem.
