![]() ![]() There was some initial interest in Xylella fastidiosa, but subsequent tests gave inconclusive results. Initial surveys did find several pathogens, such as Phytophthora, Armillaria, Neonectria, Nectria, and Ganoderma, but none were found in enough of the declining bigleaf maple to suggest that they were the primary cause of the decline. Decline in bigleaf maples has also been reported throughout the tree’s entire geographic range, including in California, Oregon, and British Columbia. These are all common signs that something is amiss with the tree, either from drought, root disturbance, chemical imbalance, or pathogen. Symptoms of the decline include partial or entire crown dieback, discoloration and reduced size of the leaves, crown thinning, and death. Forest pathologists at Washington DNR have been investigating the increase in mortality and symptoms in bigleaf maples since 2011, when numerous calls from concerned members of the public and land managers began coming in. Photo by Jacob Betzen.Īs of the end of 2018, there was no sign of recovery in sick and dying bigleaf maple throughout Western Washington. WHAT COULD BE CAUSING THE DECLINE IN BIGLEAF MAPLES ( ACER MACROPHYLLUM) ? Crown dieback, thinning, reduced leaf size, and discoloration in bigleaf maple tree. This article is an update to those published by the Tree Link in October 2014, “ Bigleaf Maple Dieback in Western Washington? ”, and the follow-up articles in September of 2015, ” What’s Going on with Bigleaf Maple?“, and in August 2016, “ Bigleaf Maple Decline, Update and Next Steps”. ![]()
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