korean pine brown needles
I have had a korean pine in my yard for about 5 years and it has grown and had pine cones. It seems healthy but has lots and lots of brown on the end of the needles. It does not appear on the new growth. A neighbor has the same tree but it is all green. His is close to his house and sheltered from the western sun in the winter. We water during the winter (and summer of course). Anything we can do?
Denver County Colorado
Since you don't observe brown tips on the new growth, I suspect you are looking at either winter desiccation or possibly freezer burn. It is possible that this conifer prefers a more protected location, like you neighbor's, or maybe this is the result of a one-time storm event. Trees that are cold hardy here are not necessarily adapted to intense sunlight a mile high or extreme temperature fluctuations. Southern and western exposures can be problematic because in winter those exposures warm up, plant cells become active, and then temperatures drop at sunset or a storm blows in and the plant is damaged.
Korean Pines (PInus koraiensis) hold their needles for three years. As long as the new growth is green and healthy, your tree will outgrow this damage. Next winter, keep a closer eye on soil moisture than you did last winter to see if that helps. If it is freezer-burn, as opposed to moisture at the roots, there's not much you can unless you create protection from intense sunlight and storms. Building shade with another planting or a structure would help keep cells dormant but that might not be aesthetically pleasing in your landscape.
If you'd like to have someone examine the needles closely and check growth increments, bring a branch into the Denver Extension office at 888 E. Iliff Ave. (720-913-5270). Alternatively, get an arborist out for on-site evaluation.