Our white pine trees, about 10 years old, have thrived. Now, large amounts (many more than is typical) of the needles are turning brown. We're worried the trees may be dying, Any suggestions?
We like to think evergreens are always green and never shed their needles, but nature recycles even these ‘leaves’ once they are old in favor of healthier younger tissue. Annual needle drop of white pines occurs from the interior toward the trunk of the plant. White pines normally drop their older needles in the fall (other species of evergreens drop needles every 2-9 years). White pines with an excessive amount of brown needles could be suffering from white pine decline.
One form of decline occurs on established trees 10 years or older planted in an unsuitable site. This is a condition that occurs over time. Environmental factors are responsible such as incorrect watering, compacted clay soils, nutrient deficiencies, soil pH fluctuations and insect damage. Many times these issues cannot be easily be resolved or corrected.
White pine root decline or procerum root disease, is an infectious disease of the root system. Younger trees are usually affected. The disease presents itself with a thinning canopy and sap produced at the trunk base. There is no ‘cure’ for infected trees but they should be removed to prevent the spread of this fungi to other pines.
Phytophthora root rot is also seen in young trees. The site is usually wet with poor drainage. Symptoms include rapid wilting, browning and dieback. Certain fungicide drenches are used in a commercial setting but are rarely used by homeowners.
I have included a link to publication UK has on why pines turn brown in our Kentucky landscapes:
Site selection is the key for healthy pines. You may choose to have the site evaluated by a certified arborist if you decide to replace the tree.
Feel free to contact our office if you have other questions.
Let me know if I can help you further!
Jefferson County Cooperative Extension Service
810 Barret Ave
Louisville KY 40204