am not 100% sure if my blue spruce has Rhizosphaera or some other type of disease. As you will see in the pictures it has lost needles in a particular area. This area is lighted by an outside LED light. Could maybe my LED light cause this? Thanks for the help.
Thanks for posting your question to the MyWoodlot forum! A few months ago, a forum user asked a similar question about causes of blue spruce needle loss. These extension articles discuss possible reasons for blue spruce needle loss, as well as treatment options for Rhizosphaeara:
New Mexico State University publication, Rhizosphaera Needle Cast Disease of Blue Spruce - has a good paragraph on Disease Management: aces.nmsu.edu/pubs/_h/H163/welcome.html
Purdue University publication, Why Spruce Trees Lose Their Needles - explains a telltale sign of Rhizosphaera, tiny black dots arranged in rows on infected needles: extension.purdue.edu/article/29053
"There are no effective chemical controls for Cytospora canker. Avoid wounding lower branches with lawn mowers. A very important management tool is to prune out and destroy cankers as soon as they are observed. Prune only during dry weather to avoid spreading spores to healthy branches."
For now, I would try pruning out that branch with the fungus. The bottom line though is that you'll need to try to determine what is causing the needle loss/fungus. If you have a hand lens, you can look for round, black fruiting bodies sticking out of the tiny pore-like openings (stomata) on both green and brown needles. Apparently, this is indicative of Stigmina or Rhizosphaera, but you'll need an expert (not me) with a microscope to tell the difference (
Wow, I'm in over my head here! I'm not sure where you are based, but if you're in New York, I'd try the local Cornell Cooperative Extension office. Also, see what you can learn from the articles I've shared. For example, it sounds like this summer, if it is something like Rhizosphaera, you should see needles turning yellow and reddish purple this summer (