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N.D. (KFYR) – A deadly tree disease has officially been detected in North Dakota
The North Dakota Forest Service confirmed that pine wilt disease has been identified in Scotch pine trees in Ransom County at the Sheyenne River State Forest and in Sargent County near Forman. The South Dakota State University plant pathology lab confirmed the findings on August 11, 2026
Pine wilt disease is caused by nematodes, which are microscopic, parasitic roundworms. They are spread from tree to tree by native sawyer beetles. Once inside, the nematodes cause the tree’s water-transporting pores to collapse, rapidly starving the tree of water and nutrients
There is currently no effective treatment for pine wilt
According to NDFS, afflicted trees decline rapidly. Needles first turn grayish-green before progressing to yellow and reddish-brown, though they often remain attached to the branches. While non-native Austrian pines may take two seasons to die, Scotch pines typically succumb within a single season
Because non-native pines like Scotch, Austrian and Mugo pines are widely used in North Dakota’s windbreaks and residential landscaping, forestry officials are urging residents to monitor their properties. As summer temperatures rise, the disease is expected to migrate farther north through the state
- Slow the spread: The best course of action is the immediate removal and destruction of infected wood
- Diversify replanting: Forestry officials advise planting native conifers, such as the Ponderosa pine, rather than non-native species
- Get help: If you suspect a tree is infected, you can submit a report using the “Sick Tree Assistance” form on the North Dakota Forest Service website or contact a local county extension agent
- Testing can only confirm the disease from samples taken when the nematodes are active, which occurs between late July and early September
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