How to Identify and Manage Pine Wilt Disease and Treat Wood Products Infested by the Pinewood Nematodes

Author
Michelle Cram, Plant Pathologist, USDA Forest Service Southern Region, Forest Health Protection.

Jim Hanson, Forest Entomologist, USDA Forest Service Northeastern Area State & Private Forestry, Forest Health Protection.

Pine wilt is a disease of pine (Pinus spp.) caused by the pinewood nematode, Bursaphelenchus xylophilus. The pinewood nematode is native to North America and is not considered a primary pathogen of native pines, but is the cause of pine wilt in some non-native pines. In countries where the pinewood nematode has been introduced, such as Japan and China, pine wilt is an important non-native disease.

The pinewood nematode (Fig. 1) is transmitted (vectored) to conifers by pine sawyer beetles (Monochamus spp.) (Fig. 2) either when the sawyer beetles feed on the bark and phloem of twigs of susceptible live trees (primary transmission) or when the female beetles lay eggs (oviposition) in freshly cut timber or dying trees (secondary transmission). Nematodes introduced during primary transmission can reproduce rapidly in the sapwood and a susceptible host can wilt and die within weeks of being infested if conditions are favorable to disease development.

USDA Forest Service
Northeastern Area
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