Concolor with needle drop

[todd48309]

Hello All - I have a question about a concolor fir that I have in a berm in my back yard in SE Michigan. It has a lot of needles turning brown, and the same thing happened last fall. The tree has been growing about 18-24 inches per year, but the needles turning brown has me concerned. It is located in a berm with two other concolors. Please see included pics. The one I am concerned about it on the far right. I did a little research and found something from Michigan State University that mentioned "The fungal pathogen Phyllosticta spp.". Any ideas on what this could be, and how do I treat it? Also, would removing some of the lower branches to increase airflow help? I have read that this can spread to other concolors so I am very concerned about the health of not just this tree but the other concolors that I have near it. Thank you in advance for your time and consideration.

 

[Raintree]

Have you ruled out rust mites?

 

[todd48309]

Have you ruled out rust mites?

I shook a branch while holding a 5 inch paper plate below. Many needles fell off, and I noticed 4-5 very small insects on the plates. See pics. Would these be mites?

 

[Raintree]

Not mites, the needle damage would have been done earlier in the year. Think about how long it takes for the cut Christmas tree to brown out. If the mites are still active you would find them on the new growth. Interior browning could be caused by nutrient deficiencies however with near by trees unaffected I would lean towards mite infestation. They over winter in the egg stage, Horticultural oil is your friend.

https://www.canr.msu.edu/news/possi...edle_shedding_and_trunk_splitting_of_fraser_f