The UW Lab Lens summarizes current pests, diseases, and problems occurring throughout Wisconsin to help you stay ahead of pests in your garden or landscape.
Weekly Plant Disease Update
By Brian Hudelson, UW Plant Disease Diagnostics Clinic Director
Website: pddc.wisc.edu
Brian Hudelson reported a wide range of plant disease issues, many driven by persistent rainfall and saturated soils.
- Woody Ornamentals
- Ginkgo & Catalpa: Poor growth and dieback, likely due to winter injury and root stress.
- Verticillium Wilt: Suspected in catalpa and confirmed in other hosts.
- Oak Wilt, Tubakia Leaf Spot and Anthracnose: On oaks.
- Gymnosporangium Rusts: Including pear trellis rust on ornamental pear.
- Fire Blight: On ornamental pear.
- Rose Rosette Disease: On rose. Viral, spread by mites. Removal is the only control.
- Fruit Crops
- Bacterial Canker: On sweet cherry.
- Brown Rot: On cherry fruit; prune infected twigs and remove mummified fruit.
- Pea Root Rot: Widespread in commercial fields due to poor rotation and wet soils.
- Herbaceous Ornamentals
- Verticillium Wilt: On Aralia.
- Southern Blight: On hosta; aggressive and showing increased prevalence in Wisconsin with warmer, wetter conditions.
- White Mold (Sclerotinia): On European ginger.
- Evergreens
- Cytospora Canker: On spruce, confirmed by observing fruiting bodies.
Additional Plant Disease Resources
- Anthracnose – UW Plant DIsease Factsheet
- Bacterial Canker – UW Plant DIsease Factsheet
- Brown Rot – UW Plant Disease Factsheet
- Cytospora Canker – UW Plant Disease Factsheet
- Fire Blight – UW Plant Disease Factsheet
- Gymnosporangium Rusts – UW Plant Disease Factsheet
- Oak Wilt – UW Plant Disease Factsheet
- Southern Blight – UW Plant Disease Factsheet
- Tubakia Leaf Spot – UW Plant Disease Factsheet
- Verticillium Wilt of Trees and Shrubs – UW Plant Disease Factsheet
- White Mold – UW Plant Disease Factsheet
Weekly Insect Pest Summary
By PJ Liesch, UW Insect Diagnostic Lab Director
Website: insectlab.russell.wisc.edu
PJ Liesch highlighted a diverse range of insect activity across Wisconsin, with several notable trends.
- True Armyworms: Continued reports, especially in southwest Wisconsin. Primarily an issue in agricultural fields, but also found feeding on nearby lawns and crops.
- Elm Zigzag Sawfly: Increasing damage, especially on Siberian elms.
- Japanese Beetles: Active, especially in northern counties.
- European Chafer: Confirmed in Washington County; expanding in southeast Wisconsin.
- Pine Needle Scale: Present; treatment timing should follow degree-day models.
Additional Insect Pest Resources
- Degree Days for Common Landscape Pests (Pine Needle Scale) – UW Horticulture
- Elm Zigzag Sawfly – UW Horticulture
- European Chafer – UW Horticulture
- Insect Identification Tool: Pine Insects – UW Entomology
- Japanese Beetle – UW Horticulture
- Managing True Armyworm in Wisconsin Corn and Grain Fields – UW Crops & Soils
- Sawflies – UW Horticulture
