Pacific Region

By R. S. Hunt

Introduction

Discolored current or 1-year-old needles on pine trees are so prevalent that the condition is often considered natural; however, this symptom is generally the result of diseases or insects. The destruction of foliage may result from non-infectious or infectious disease agents. Noninfectious dis-ease agents, such as early or late frosts, winter drying, drought, or air pollution are adverse elements of the environment. Infectious foliage diseases are caused by fungi. Some of the more common fungi that cause premature defoliation of pines in the Pacific Region are the subject of this leaflet. Additionally two commonly observed fungi, Lophodermium pinas-tri and L. nitens, which are weakly virulent pathogens, are included.