Large oak tree showing signs of disease - Ask Extension
I am concerned with the health of this 60 foot oak that is on our property. Does this look like something we can and should treat?
Knowledgebase
Large oak tree showing signs of disease #805871
Asked August 11, 2022, 6:23 PM EDT
I am concerned with the health of this 60 foot oak that is on our property. Does this look like something we can and should treat?
Genesee County Michigan
Expert Response
Hello Louise,
Based on what I see in the image, I have never seen the perimeter of oak leaves so uniformly brown. Browning is usually more splotchy. The fact that the leaves are turning yellow but the veins remain green indicates that your tree may suffer from iron chlorosis caused by iron deficiency, usually in high pH soils (pH above 7.0). Other causes of yellowing need to be ruled out first. For example, leaf yellowing can be due to insect or disease problems (pathogenic diseases caused by fungi or other organisms), herbicide misuse, or a history of overwatering.
Symptoms of iron chlorosis are:
- newest leaves towards the ends of branches are generally yellowed
- veins of affected leaves remain green
- in advanced cases, leaf edges become scorched, and leaf interiors show dead brown areas as cells die
In addition to a high pH, some causes of iron chlorosis are insufficient soil oxygen, compacted clay soils, and overwatering. These can result in lowered levels of soil oxygen. Also, when plants are overfertilized with phosphorus, iron chlorosis may develop as roots take up phosphorus to exclude iron.
To determine if iron chlorosis is the issue, your first step should be to conduct a soil test. Self-mailer soil test kits from the Michigan State University Plant and Pest Diagnostic Lab are available. You can obtain them at the link below. Full instructions are there and also come with the kits. The cost is $25. The Lab will make recommendations for any needed soil amendments.
https://homesoiltest.msu.edu/
Treating iron chlorosis is a complex process. Your best resource for diagnosing and treating your tree is to consult a certified arborist. Certified arborists have training in plant selection, care, diseases/pests, and have passed a certification test. They can do an onsite evaluation of the trees. You can find certified professionals in your zip code here: https://www.treesaregood.org/findanarborist/arboristsearch
Here is some additional information on this topic:
https://www.extension.purdue.edu/extmedia/BP/BP-27-W.pdf
https://forestry.usu.edu/trees-cities-towns/tree-care/preventing-iron-chlorosis
Hope this helps!!
Based on what I see in the image, I have never seen the perimeter of oak leaves so uniformly brown. Browning is usually more splotchy. The fact that the leaves are turning yellow but the veins remain green indicates that your tree may suffer from iron chlorosis caused by iron deficiency, usually in high pH soils (pH above 7.0). Other causes of yellowing need to be ruled out first. For example, leaf yellowing can be due to insect or disease problems (pathogenic diseases caused by fungi or other organisms), herbicide misuse, or a history of overwatering.
Symptoms of iron chlorosis are:
- newest leaves towards the ends of branches are generally yellowed
- veins of affected leaves remain green
- in advanced cases, leaf edges become scorched, and leaf interiors show dead brown areas as cells die
In addition to a high pH, some causes of iron chlorosis are insufficient soil oxygen, compacted clay soils, and overwatering. These can result in lowered levels of soil oxygen. Also, when plants are overfertilized with phosphorus, iron chlorosis may develop as roots take up phosphorus to exclude iron.
To determine if iron chlorosis is the issue, your first step should be to conduct a soil test. Self-mailer soil test kits from the Michigan State University Plant and Pest Diagnostic Lab are available. You can obtain them at the link below. Full instructions are there and also come with the kits. The cost is $25. The Lab will make recommendations for any needed soil amendments.
https://homesoiltest.msu.edu/
Treating iron chlorosis is a complex process. Your best resource for diagnosing and treating your tree is to consult a certified arborist. Certified arborists have training in plant selection, care, diseases/pests, and have passed a certification test. They can do an onsite evaluation of the trees. You can find certified professionals in your zip code here: https://www.treesaregood.org/findanarborist/arboristsearch
Here is some additional information on this topic:
https://www.extension.purdue.edu/extmedia/BP/BP-27-W.pdf
https://forestry.usu.edu/trees-cities-towns/tree-care/preventing-iron-chlorosis
Hope this helps!!
Firstly, thank you for all the wonderful information. I will consult with a certified arborist as you suggested. We have another large oak with yellow leaves, but no browning. Our soil is heavy clay and we do roll a pokey roller over our lawn a few times a year. Again, thank you for the thoughtful service you provide.
You are welcome - Have a great day!!
