Compiled by Brian Hudelson and Hulubanche Kassa
The following diseases/disorders were identified at the Plant Disease Diagnostics Clinic from July 18, 2026 through July 24, 2026.
Broad-Leafed Woody Ornamentals
Plant: Aspen
Disease/Disorder: Transplant Shock (Suspected)
Pathogen: None
County: Dane
Plant: Bladdernut
Disease/Disorder: Ramularia Leaf Spot
Pathogen: Ramularia sp.
County: Dane
Plant: Lilac (Shrub)
Disease/Disorder: Septoria Leaf Spot
Pathogen: Septoria sp.
Counties: Dane, La Crosse
Plant: Maple (Sugar)
Disease/Disorder: Massaria Canker
Pathogen: Massaria sp.
County: Dane
Plant: Maple (Sugar)
Disease/Disorder: Steganosporium Canker
Pathogen: Steganosporium sp.
County: Waukesha
Plant: Maple (Sugar)
Disease/Disorder: Verticillium Wilt
Pathogen: Verticillium sp.
County: Dane
Plant: Maple (Unspecified)
Disease/Disorder: Heat Stress/Sunburn
Pathogen: None
County: Manitowoc
Plant: Oak (Bur)
Disease/Disorder: Anthracnose
Pathogen: Discula sp.
County: Sheboygan
Plant: Oak (Red)
Disease/Disorder: Chlorosis
Pathogen: None
County: Waukesha
Plant: Oak (Red)
Disease/Disorder: Herbicide Damage
Pathogen: None
County: Dane
Plant: Oak (Red)
Disease/Disorder: Oak Wilt
Pathogen: Bretziella fagacearum
County: Dane
Plant: Oak (Unspecified)
Disease/Disorder: Chlorosis
Pathogen: None
County: Kewaunee
Plant: Oak (Unspecified)
Disease/Disorder: Oak Wilt
Pathogen: Bretziella fagacearum
Counties: Dane, Marathon
Plant: Pear (Ornamental)
Disease/Disorder: Pear Scab
Pathogen: Venturia pirina
County: Lincoln
Plant: Redbud
Disease/Disorder: Heat Stress/Sunburn
Pathogen: None
County: Dane
Field Crops
Plant: Soybean
Disease/Disorder: Phytophthora Root and Stem Rot
Pathogen: Phytophthora sp.
County: Outagamie
Forage Crops
No New Diseases
Fruit Crops
Plant: Apple
Disease/Disorder: Apple Scab
Pathogen: Venturia inaequalis
County: La Crosse
Plant: Apple
Disease/Disorder: Bitter Rot
Pathogen: Colletotrichum sp.
County: La Crosse
Plant: Apple
Disease/Disorder: Cedar-Apple Rust
Pathogen: Gymnosporangium juniperi-virginianae
County: La Crosse
Plant: Apple
Disease/Disorder: Frogeye Leaf Spot
Pathogen: Botryosphaeria obtusa
County: La Crosse
Plant: Pear
Disease/Disorder: Pear Scab
Pathogen: Venturia pirina
County: La Crosse
Plant: Strawberry
Disease/Disorder: Anthracnose Fruit Rot
Pathogen: Colletotrichum sp.
County: Clark
Plant: Strawberry
Disease/Disorder: Common Leaf Spot
Pathogen: Mycosphaerella fragariae
County: Marathon
Plant: Strawberry
Disease/Disorder: Root Rot
Pathogens: Phytophthora sp., Pythium sp., Rhizoctonia sp., Fusarium sp.
Counties: Clark, Marathon
Herbaceous Ornamentals
Plant: Aralia
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: Hosta
Disease/Disorder: Tobacco Rattle
Pathogen: Tobacco rattle virus
County: Pepin
Houseplants
No New Diseases
Needled Woody Ornamentals
Plant: Juniper (Chinese)
Disease/Disorder: Cytospora Canker
Pathogen: Cytospora sp.
County: Dane
Plant: Pine (Bosnian)
Disease/Disorder: Diplodia Shoot Blight and Canker
Pathogen: Diplodia sp.
County: Kenosha
Plant: Pine (White)
Disease/Disorder: Cytospora Canker
Pathogen: Cytospora sp.
County: Dane
Vegetable Crops
Plant: Bean (Snap)
Disease/Disorder: Root Rot
Pathogen: Pythium sp.
County: Waushara
Plant: Onion
Disease/Disorder: Stemphylium Leaf Blight
Pathogen: Stemphyllium sp.
County: Columbia
Plant: Tomato
Disease/Disorder: Bacterial Canker
Pathogen: Clavibacter michiganensis subsp. michiganensis
Counties: Milwaukee, Rock
Plant: Tomato
Disease/Disorder: Early Blight
Pathogen: Alternaria solani
County: Waukesha
Specialty Crops
No New Diseases
Miscellaneous
No New Entries