We live in southern Michigan and have 4 white pine trees, about 40 feet tall, in a bed area. One tree is totally brown and the other 3 are starting to have yellow needles that fall off when touched. Some of the trees have white spots on the needles. I first thought the brown tree was due to drought, but the others have been well watered. I do not want to lose these beautiful trees. There is also a blue spruce, same height, in the same bed. Please give me suggestions on where to turn for help. I have had one tree company here, but they were not much help.