It is important to identify the tree when asking this question as some are prone to different diseases. Then it is important to identify the disease causing organism (?fungus) because some treatments work better for different pests.  

Please send pictures of the tree-a closeup of the needledrop area, a closeup of adjacent healthy needles and a picture of the entire tree so we can see the pattern of needle drop.

In the meantime the following website may be of some help.  Click on the tree type and then on the problem area-needles. See: http://apps.extension.umn.edu/garden/diagnose/plant/evergreen/



This appears to be more than seasonal needle drop. I can’t see black dots on the needles.  This would indicate Rhizosphaera needle drop.  Sometimes trees will drop needles if not enough sunlight and air is circulating near them.  This tree is crowded but seems to be getting enough sunlight. Often people do trim up the lower branches to increase air circulation.

I suspect that there is a disease process happening but can’t identify it from the pictures.  I do see the black areas in the branches and it could be a fungus as you suggested. Fungi are often associated with cankers. Treating the fungus without treating the cankers is ineffective. The following websites gives more information on this:  https://hortnews.extension.iastate.edu/2007/2-21/canker.html

I recommend that you send a sample to the Plant Disease Clinic.  There are instructions at the website:  https://pdc.umn.edu/

Another option is to have an onsite inspection by an arborist.  See:  https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional