Very large spruce with needle cast ?
I have a large spruce (75 plus feet) that is approximately 50 yrs old. This year I noticed the tree has lost needles on the north side of the tree making for many bare branches. The needle lost starts on the low branches and extends upwards 30 feet or more. The north side of the tree is shaded. The south side of the tree has some bare lower branches but minimal. I had a company come out yesterday and start treatment on the tree for what they diagnosed as needle cast?? . Yesterday's treatment consisted of injections into the roots???. From what I have read about needle cast is this the time of year for treatment?? I mentioned spraying to the person treating the tree in which he replied the tree is too large. Before I get too far along with this tree service and the treatment plan they are taking, how and when should I treat this disease affecting my tree?. Is this the right time of year, late summer vs. spring?? Can I treat it myself?? From what I have read online, how does a deep root application help my problem???. This application yesterday was $250.00. How should I proceed??? Thank you.