Dear Gary:

Thanks for contacting the UVM Extension Master Gardener Helpline with your question about why your alder tree’s leaves are turning brown. From your report, it sounds like you have had the tree for awhile and this is the first time that you recall seeing this development in the tree. From the photos that you sent, it looks like the tree sits atop a small hill or berm.

As you may know, alders like to grow in wet soil, which is why they are often seen in riparian areas. Leaves turning brown sometimes indicates a lack of adequate water. It is hard to imagine that a tree in Vermont is not getting enough water given all the rain that we’ve had this summer. The weather service reports that Woodstock has received almost 27 inches of rain from June to August. Since you live in Windsor County, it is likely that you have received much more than adequate rain. Since the tree is on a hill, water may drain off quickly. However, we doubt that drainage is the issue since you indicated that you haven’t seen this problem before.

Leaves can turn brown because of too much water as well. Does water pool at the base of the tree after it rains? If so, you should try to divert the water away from the tree. This may be a temporary problem due to the tremendous rainfall central Vermont has received.

From the pictures, it appears that almost the entire tree has browned, curled leaves, which suggests a systemic problem. Diseases that affect the entire tree include Phytophthora Root Rot and Alder Phytophthora. The symptoms of these diseases are leaves that appear to wilt and then turn yellow. Did you notice any yellowing leaves before the leaves turned brown?

We also notice that there are vertical lines of small square marks on the tree bark with similar healed scars below. The Yellow Bellied Sapsucker is probably responsible for these marks. They peck into the tree bark to access the sap. Usually, sapsucker holes are round and encircle the trunk, but sapsuckers also make more shallow square holes that are not as deep as the round “drill” holes. We do not believe that the sapsucker damage is responsible for the current problem or an indication that the tree has insects since the birds generally feed on sap and not insects. We attach a link to a fact sheet that contains information about the bird and management if you want to discourage future visits. Sapsucker Damage on Woody Plants - FSA7561 (uada.edu)

If you would like to send us a sample of the affected parts of the alder for further analysis, please complete the questionnaire found at PDC_Specimen_Worksheet_fillable_form.pdf (uvm.edu) and send some green leaves and small branches with the brown leaves.

If you have any questions, please feel free to contact us again.

Regards,

Pat