Swiss Needle Cast
Disease
High Threat
Identification & Biology
Fungal disease that causes Douglas fir to shed needles prematurely. Trees look thin and yellow. Fog and moisture promote the fungus. Coastal areas worst affected.
Current Status
Worsening. Affects hundreds of thousands of acres of coastal Douglas fir.
States affected:
Oregon
Washington
What Homeowners Should Do
Improve air circulation through pruning. In severe cases, consider fungicide treatment. May need to diversify away from Douglas fir in heavily affected areas.
Identification Photos
Related Threats
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