The leaves of my river birch are turning yellow and falling off. Some of them have small dark spots on them. Some branches have lost most of their leaves. What could be the problem? What actions should I take to correct this problem. Thank You for any help you can provide.

Greetings John:

Possible problems could be birch leafminer or birch leaf blight--the former being insect related and the latter being fungus related. However, I would be remiss if I did not include environmental factors such as heat, fertility issues, lack of adequate precipitation, or even over-watering--environmental factors consistently allow secondary sources of biological origin to further complicate tree health and vigor. Insecticides can be applied if birch leafminer is the culprit. If birch leaf blight is found to be the cause, a simple solution is making sure the tree is receiving proper air circulation and promptly rake and remove all fallen leaves from the site in order to help eliminate the fungal spores.

If you are truly concerned about this tree, please contact a local certified arborist for an on-site assessment.

Illinois Arborist Association:

http://www.illinoisarborist.org/CertifiedArboristsNew.htm

Extra Reading:

http://www.na.fs.fed.us/spfo/pubs/howtos/ht_birch/ht_birch.htm