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 shared an update on plant diseases diagnosed in the lab this past week:
- Woody Ornamentals:
- Gymnosporangium rusts: Cedar-apple, cedar-hawthorn, and red star rust.
- Vascular wilts: Verticillium wilt detected in a catalpa sample and oak wilt.
- Herbicide injury: Noted on bur oak and spruce.
- Nutrient disorders: Chlorosis in red oak (most likely an iron deficiency), mouse ear in birch (nickel deficiency), which could be influenced by soil pH.
- Fruits:
- Apple scab and frog-eye leaf spot (caused by the fungus Sphaeropsis) on apple.
- Herbaceous Ornamentals
- Tobacco rattle virus on peony.
- Anthracnose on phlox.
- Evergreens:
- Lingering winter burn issues suspected, root rots, Diplodia shoot blight, and Rhizosphaera needle cast.
- Vegetables:
- Root rots in peas (Pythium, Phytophthora, Rhizoctonia, Fusarium, Aphanomyces).
- Aerial stem blight (caused by the same bacteria that cause bacterial soft rot of potato tubers and black leg on lower stems of potato plants).
- Slime molds (in particular dog vomit slime mold) in potted plants in a nursery setting. This slime mold is commonly found in association with freshly spread mulch.
Additional Plant Disease Resources
- Anthracnose – UW Plant Disease Factsheet
- Apple Scab – UW Plant Disease Factsheet
- Chlorosis – UW Plant Disease Factsheet
- Diplodia Shoot Blight and Canker – UW Plant Disease Factsheet
- Gymnosporangium Rusts – UW Plant Disease Factsheet
- Oak Wilt – UW Plant Disease Factsheet
- Red Star Rust – UW Plant Disease Factsheet
- Rhizosphaera Needle Cast – UW Plant Disease Factsheet
- Slime Molds – UW Plant Disease Factsheet
- Tobacco Rattle Virus – UW Plant Disease Factsheet
- Verticillium Wilt of Trees and Shrubs – UW Plant Disease Factsheet
Weekly Insect Pest Summary
By PJ Liesch, UW Insect Diagnostic Lab Director
Website: insectlab.russell.wisc.edu
PJ Liesch summarized insect activity from the past week:
- True Armyworms: Widespread outbreaks across Wisconsin, especially in counties in northwest Wisconsin. Reports of larvae feeding on corn, wheat, and lawns. Marching behavior noted.
- Japanese Beetles: Active statewide, especially north of Wausau. Notable damage in Iowa County.
- Other Insects:
- Two-lined chestnut borer: Still present, linked to drought and spongy moth stress.
- Galls and leaf miners: On landscape plants (galls) and vegetables (leafminers).
- Milkweed insects: Monarchs, tussock moths, swamp milkweed beetles, and others.
- Cutworms and zebra caterpillars: Feeding on brassicas (zebra caterpillars) and strawberries (variegated cutworm).
- Cucumber and squash beetles: Common in gardens.
- Bat bugs and bed bugs: Recent cases at UW Insect Diagnostic Lab. Diagnosing exact species is critical for management.
- Millipedes: Large numbers reported in some areas.
- Bumblebee and yellowjacket nests: Increasing reports in yards.
Additional Insect Pest Resources
- Japanese Beetle – UW Horticulture
- Two-lined Chestnut Borer – UW Horticulture
- Leafminers (vegetables) – UW Horticulture
- Cucumber Beetles – UW Horticulture
- Millipedes – UW Horticulture
- Wisconsin Bee Identification Guide – UW Horticulture
