Dying, Off, Color Pine Needles Normal in Autumn, Colorado State Forest Service

Ponderosa and lodgepole pines and some spruce and fir species Colorado shed older, interior needles as part of an annual growth cycle in September and October.

Conifers: Evergreen Trees and Shrubs - Acadia National Park (U.S. National Park Service)

Columbia Gorge

My Conifers Are Losing Needles! Should I Be Concerned? - Independent Tree

Best National Parks to Visit in October & Fall Colors

Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds

5 of the Most Common Tree Diseases of Wisconsin (And What You Can Do) Earth Development

Category: Trees - K-State Research and Extension Horticulture Newsletter

Types of Coniferous Trees: Forest Conifers Vs. Deciduous Vs. Evergreen

JeffCo Master Gardeners: Ponderosa pines, spruce may exhibit 'winter burn' by Colorado State Forest Service

Meet the beetles

Help! I think my Ponderosa Pine is Dying!

Why Do Pine Trees Lose Their Needles

Borers of Pines and Other Needle Bearing Evergreens in Landscapes

Pinus albicaulis