Dying Fir trees

Question: We live in a rural area in East Central MN - near the border of USDA Zone 3a and 3b.  We have been losing our mature Fir trees one by one over the last three years, and cannot figure out what is happening and how to help them / save them.  We're especially concerned because an old privacy hedge between our house and the neighbors is entirely Fir, and we would be devastated to lose that stand (although are planting a variety of other evergreens in the area to help with biodiversity and as a preventative).  

Here's what we're observing:
1. Firs grouped in an area are not all going at once - they are dying one at a time, which leads us to believe this is not an environmental problem (unsuitability of soil in planted areas, drought, flood, etc.).

2. The Firs start with a small rust-colored patch of needles, and then it quickly (within a matter of months) spreads to the entire tree - so the entire tree is fully rust colored (and, presumed dead - but they retain all their needles - full and bushy).  We have cut down some of the trees when they're finally completely rust colored, but then it starts again on a nearby tree.

Is this fungal?  Insect damage?  Something else?  Is there anything we can do to protect and save our Fir trees?  We're happy to collect and send in samples for testing, if needed.

A thousand thanks for your time and consideration - we're deeply grateful for any assistance you can provide!

responder: Deb Reierson  Replied July 30, 2023, 6:22 PM EDT
response: It appears you may have a fungal disease. Your description of it affecting one or two trees at a time suggests this. Also I see it is starting from the ground up. The top photo does look like there are fungal spores at the tips of the branches. This is not something we can diagnose through photos so I would encourage you to either hire a certified arborist to come look at them or send in a sample to the University for testing.  https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/fir/needlesyellow.html https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional https://extension.umd.edu/resource/needle-cast-diseases-evergreen-trees And I trust that no one is spraying glyphosate around you but just in case: https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/fir/needlesyellow.html

responder: The Question Asker Replied August 03, 2023, 4:19 PM EDT
response: Many thanks for your kind and thorough message, Deb - this is a very helpful start.  Due to the remote nature of our location, I think that sending a sample into the University for testing is our best bet at this time - however, I am not seeing information about where and how best to send a sample that can be useful… would you be willing forward a link to this information?cheers,Leigha-- Leigha Horton, SAG-AFTRA, CNFTGvoiceover artistwww.LeighaHorton.com612.879.0303certified nature and forest therapy guidementor + consultantwww.SilvaeSpiritus.com323.292.7971On Jul 30, 2023, at 5:22 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: Deb Reierson  Replied August 03, 2023, 4:31 PM EDT
response: sorry, I should have included this link to submit a sample. https://pdc.umn.edu/submit-sample Good luck,