Maybe just call an arborist and get an estimate for what they would charge? Have you had it tested to see if it is really needle cast and not something else? If it is needlecast then it can be sprayed in the spring, and that time is coming up. UofM here mentions Chlorothalonil.
I had Davey Tree dude come out last week to look at one of my columnar white pines. Two are fine and the third at the bottom of a slope is turning yellowish green. I was guessing it has just been too wet last summer and last fall but wanted to rule out disease. They tested needles, nothing showed up so I am probably right, just too wet. Not sure they are even charging for the visit or test, just treatment if I had gotten any. Only thing they suggested was fertilizer but I am not inclined to do that when the tree is stressed out. Going to see how the new growth goes that is starting tot "candle" now. And I got to pick his brain on my magnolia scale that I treat myself with a systemic drench. I hire Davey to spray my big crabapple for scab each spring.