Thank you for contacting Ask Extension! Loss of needles can be caused by many things, but is often environmental in origin. Although there are a few pathogens that might be infecting your tree, these tend to be opportunistic, meaning that an unstressed tree is unlikely to succumb to significant damage. In the photo it appears the damage is greater on one side, which is typical of winter desiccation. When the ground is frozen, the tree cannot take up water, but will still lose water through its needles. The damage is often worse on one side, where it is most exposed to the wind, or to additional sources of heat, such as rocks radiating solar heat. The damage may also have resulted from a cascade of factors. For example, drought stress is common, and leaves a tree in a weakened state. Although your tree will tolerate mild drought, it will be weakened by prolonged drought, particularly when accompanied by high temperatures. The effects of drought may not be visible for several years, but the stress leaves the tree vulnerable to other stressors, including pathogens.

During periods of prolonged drought, consider irrigating deeply once per week. A low rate of nitrogen fertilizer couldn’t hurt to help provide an energy boost, as well. If you would like to rule out pathogens (and insects), consider sending a sample to Michigan State University’s Plant and Pest Diagnostics. You might also consider getting a soil sample, to see if there are any problems with pH or nutrient levels: Home soil test.

Your jack pine should hold needles for 2 – 4 years, and last year’s tips should not be turning brown. That could also be caused by winter desiccation, or any number of other things. You might want to submit a new request to Ask Extension and include an overview photo and two images showing close-up examples of the injury. If the injury varies in intensity, have one photo show early stages, and the second more advanced.

Some additional information is available at:

Trees and drought

Cold injury in conifers.