What causes rust-colored branches on a Blue Spruce tree?

Question

I have a Blue Spruce tree in my front yard. It's about 15 years old. This year, for the first time, I've noticed rust-colored branches occurring throughout it. Do you have any idea of the cause(s) of it, or any treatment(s) I should use?

Thanks for your help!

Answer 1

Cytosporta canker.

Answer 2

There are a few things that can cause this. One of them is the tree is stressed out by pruning or I should say; over pruning. Sometimes it can be caused by spreading  weed killer for lawns on its roots. They don't tell you this on the directions but weedkiller for lawns can stress out evergreens.

Answer 3

it might be spider mites. try looking at the green plant right next to the dying part. look with a magnifying lens. take your time and watch for really small movements. you can also get a white and a black piece of paper, bang your sample against the  paper and look closely. if you see tiny little mites, wash the tree off with  water in which you add a teaspoon dishsoap and half a teaspoon of canola oil. spray in the evening and wash off in the morning, three or four times. that usually takes care of spider mites.

Answer 4

Maybe you should take a branch of the rust-coloured Blue Spruce to an expert for advice.

There is a rust caused by fungi.