Hi there,

Unfortunately, die back in bigleaf maple is being seen all over our region and is potentially associated with higher temperature and drought, and associated vapor pressure deficits. Symptoms of dieback include premature yellowing of leaves, thinning and entire crown dieback. Branches sometimes have clumps of unnaturally small leaves and heavy seed crops. Leaves may have edges that resemble leaf scorch. I've linked a resource below that talks about this in a bit more detail. Sometimes, drought-stressed trees are more susceptible to pests and pathogens as well.

OR Dept of Forestry "Why is my bigleaf maple dying?": https://www.oregon.gov/odf/Documents/forestbenefits/tree-declines-bigleaf-maple.pdf

Study on bigleaf maple decline in western Washington: https://digital.lib.washington.edu/researchworks/handle/1773/43386

However, the rapid browning and defoliation of bigleaf maple we saw in the past few months at Mary's River Park in Philomath is still a mystery. Your inquiry is timely, because I was just out there last week with a forest pathologist who could not locate any signs of a pest or pathogen, so we think it may be abiotic/environmental. I have a call out to the city to see if they are aware of any changes with management at the park, but given you are seeing the same thing on your property, it's likely that it's related to the heat and drought and not chemicals or dumping or something like that.

Please let me know if you have any further questions.

Hi Janice,

Thanks for the information. Yes, the rapid defoliation of the bigleaf maples is stark and alarming. I am hoping to chat with parks & rec to see what they're long term plan is. Unfortunately, the extended periods of hot and dry weather rarely punctuated by small amounts of rain is quite stressful for our trees.

Please let me know if you have any additional questions.

Hello,

I got a response from Philomath Public Works on the loss of water from the Mary's River Park slough. The new construction is not the cause for the draining of the slough. Instead, the DEQ instructed Philomath Public Works to remove the discharge pipe that fed water into the slough. It sounds like there's a history with this  discharge pipe dating back to 2017, but in any case Philomath Public Works has tried to get approval to continue feeding water to the slough. I will advise you to contact Kevin Fear with any further questions on the matter, as they will have the most accurate and up to date information.

Kevin Fear

City of Philomath

Public Works Director

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