Compiled by Brian Hudelson and Dante Tauscheck
The following diseases/disorders were identified at the Plant Disease Diagnostics Clinic from August 2, 2025 through August 8, 2025.
Broad-Leafed Woody Ornamentals
Plant: Aspen (Quaking)
Disease/Disorder: Venturia Leaf and Shoot Blight
Pathogen: Venturia morelettii
County: Dane
Plant: Beech
Disease/Disorder: Cold Injury (Suspected)
Pathogen: None
County: Ozaukee
Plant: Beech
Disease/Disorder: Phomopsis Canker
Pathogen: Phomopsis sp.
County: Ozaukee
Plant: Boxwood
Disease/Disorder: Volutella Canker
Pathogen: Volutella sp.
County: Dane
Plant: Catalpa
Disease/Disorder: Verticillium Wilt
Pathogen: Verticillium sp.
County: Dane
Plant: Elm (American)
Disease/Disorder: Dutch Elm Disease
Pathogen: Ophiostoma sp.
County: Dane
Plant: Hydrangea
Disease/Disorder: Girdling (from attached strings)
Pathogen: None
County: Door
Plant: Hydrangea
Disease/Disorder: Root Rot
Pathogen: Phytophthora sp.
County: Sawyer
Plant: Lilac
Disease/Disorder: Root Rot
Pathogen: Phytophthora sp.
County: Sawyer
Plant: Lilac
Disease/Disorder: Verticillium Wilt (Suspected)
Pathogen: Verticillium sp.
County: Dodge
Plant: Magnolia
Disease/Disorder: Root Rot
Pathogen: Rhizoctonia sp.
County: Dane
Plant: Maple (Unspecified)
Disease/Disorder: Anthracnose
Pathogen: Discula sp.
County: La Crosse
Plant: Maple (Unspecified)
Disease/Disorder: Steganosporium Canker
Pathogen: Steganosporium sp.
County: Waukesha
Plant: Ninebark
Disease/Disorder: Powdery Mildew
Pathogen: Oidium sp.
County: Dane
Plant: Oak (Swamp White)
Disease/Disorder: Chlorosis
Pathogen: None
County: Dane
Plant: Oak (White)
Disease/Disorder: Anthracnose
Pathogen: Discula sp.
County: Dane
Plant: Oak (White)
Disease/Disorder: Tubakia Leaf Spot
Pathogen: Tubakia dryina
County: Dane
Plant: Oak (White)
Disease/Disorder: White Rot
Pathogen: Irpex lacteus
County: Dane
Plant: Rose
Disease/Disorder: Anthracnose
Pathogen: Gloeosporium sp.
County: Sawyer
Plant: Rose
Disease/Disorder: Gray Mold (Botrytis Blight)
Pathogen: Botrytis cinerea
County: Sawyer
Plant: Rose
Disease/Disorder: Root Rot
Pathogen: Phytophthora sp.
County: Sawyer
Field Crops
Plant: Corn (Field)
Disease/Disorder: Southern Corn Rust
Pathogen: Puccinia polysora
Counties: Grant, Green, Green Lake
Forage Crops
No New Diseases
Fruit Crops
Plant: Apple
Disease/Disorder: Cold Injury (Suspected)
Pathogen: None
Counties: Waupaca, Wood
Plant: Apple
Disease/Disorder: Root Rot
Pathogen: Phytophthora sp.
County: Wood
Plant: Apple
Disease/Disorder: Marssonina Leaf Blotch
Pathogen: Marssonina coronaria
County: Dunn
Herbaceous Ornamentals
Plant: Hosta
Disease/Disorder: Southern Blight
Pathogen: Athelia rolfsii
County: Columbia
Houseplants
No New Diseases
Needled Woody Ornamentals
Plant: Arborvitae
Disease/Disorder: Cytospora Canker
Pathogen: Cytospora sp.
County: Door
Plant: Arborvitae
Disease/Disorder: Root Rot
Pathogens: Phytophthora sp., Pythium sp., Fusarium sp.
Counties: Dane, Racine
Plant: Arborvitae
Disease/Disorder: Sphaeropsis Canker
Pathogen: Sphaeropsis sp.
County: Dane
Plant: Fir (Balsam)
Disease/Disorder: Cytospora Canker
Pathogen: Cytospora sp.
County: Waukesha
Plant: Juniper
Disease/Disorder: Winter Burn
Pathogen: None
County: Dane
Plant: Larch (Unspecified)
Disease/Disorder: Herbicide Damage (Suspected)
Pathogen: None
County: Washington
Plant: Spruce (Bird’s Nest)
Disease/Disorder: Phomopsis Canker
Pathogen: Phomopsis sp.
County: Dane
Plant: Spruce (Norway)
Disease/Disorder: Transplant Shock (Suspected)
Pathogen: None
County: Waukesha
Vegetable Crops
Plant: Cucumber
Disease/Disorder: Anthracnose
Pathogen: Colletotrichum orbiculare
County: Manitowoc
Plant: Onion
Disease/Disorder: Stemphylium Leaf Blight
Pathogen: Stemphylium sp.
County: Waushara
Plant: Pepper
Disease/Disorder: Bacterial Spot
Pathogen: Xanthomonas sp.
County: Iowa
Plant: Potato
Disease/Disorder: Foliar Blight
Pathogen: Phytophthora nicotianae
County: Adams
Plant: Tomato
Disease/Disorder: Walnut Toxicity (Suspected)
Pathogen: None
County: Dane
Specialty Crops
No New Diseases
Miscellaneous
Mushroom ID: Glistening Inky Cap (Coprinellus micaceus)
County: Walworth