My Serbian pine, which was planted almost two years ago is loosing it's pine needles (not cones). At present the top two feet are bare and one/two middles branches. I fertilized it this spring and have sprayed it twice with fungaside and diazon, as per instruction of the landscaper that planted it. This advice was given because the maple tree growing beside it has mildew/fungus and mites. We also trimmed back the maple tree to it's property line. Any other suggestions. We have had a very cold winter, and very wet, windy and cold spring and now we are in a heat wave (34C), plus humidity. There is new growth on the branches, but also brown needles. The tree is approxmately two storeys high.