This is the fifth in a series of columns prepared by the staff at the award winning West Seattle Nursery.  The Nursery is open for shopping, following COVID guidelines and they offer an array of trees, shrubs, bedding plants, garden supplies, decor and gift items. They are located at 5275 California Ave SW and you can find them online at https://www.westseattlenursery.com

This lethal fungal disease was first seen in the Seattle area in 2017, and it appears to be spreading.  Three trees in the Alki Beach area have been identified with the disease recently. Species that seem most susceptible are sycamore maples, Japanese and Norway maples, horse chestnuts, and our native big leaf maples and Pacific dogwoods.

This disease shuts down a tree’s vascular system, essentially starving it. When the fungus fruits, it sloughs bark off of the tree and releases billions of spores into the air.  These spores can infect other trees, and they can cause problems for humans, too. People who have prolonged contact with diseased trees, especially those who have weak immune systems or a history of lung issues, are susceptible to severe lung inflammation.

There is no known cure for infected trees. However, it is known that stress from high temperatures and lack of water predisposes trees to disease. The best thing you can do for your trees is to water them deeply, at least once a week, during our dry, summer season. Remember that roots spread 2 -3 times as wide as the tree is tall, so water in a wide circle around the tree, not just at the trunk.

For more information about this disease, or to report a tree that might be infected, visit Forest Health Watch.

You can also learn more in this story from the Seattle Times.