Compiled by Brian Hudelson and Hulubanche Kassa
The following diseases/disorders were identified at the Plant Disease Diagnostics Clinic from August 29, 2026 through September 4, 2026.
Broad-Leafed Woody Ornamentals
Plant: Lilac (Common)
Disease/Disorder: Herbicide Damage
Pathogen: None
County: Washington
Plant: Maple (Unspecified)
Disease/Disorder: Bleeding Canker/Root Rot/Crown Rot
Pathogen: Phytophthora sp.
County: Dane
Plant: Musclewood
Disease/Disorder: Phomopsis Canker
Pathogen: Phomopsis sp.
County: Dane
Plant: Oak (Bur)
Disease/Disorder: Anthracnose
Pathogen: Discula sp.
County: Dane
Plant: Oak (Bur)
Disease/Disorder: Oak Wilt
Pathogen: Bretziella fagacearum
County: Dane
Plant: Oak (Bur)
Disease/Disorder: Tubakia Leaf Spot
Pathogen: Tubakia sp.
County: Dane
Plant: Oak (Unspecified)
Disease/Disorder: Herbicide Damage
Pathogen: None
County: Dane
Plant: Oak (Unspecified)
Disease/Disorder: Tubakia Leaf Spot
Pathogen: Tubakia sp.
County: Dane
Plant: Pear (Ornamental)
Disease/Disorder: Fire Blight
Pathogen: Erwinia amylovora
Counties: Dane, Waukesha
Plant: Sycamore (American)
Disease/Disorder: Frost Crack
Pathogen: None
County: La Crosse
Plant: Sycamore (American)
Disease/Disorder: Phomopsis Canker
Pathogen: Phomopsis sp.
County: La Crosse
Plant: Walnut (Black)
Disease/Disorder: Phyllosticta Leaf Spot
Pathogen: Phyllosticta sp.
County: Portage
Field Crops
Plant: Sorghum
Disease/Disorder: Phytoplasma Disease
Pathogen: Unspecified Phytoplasma
County: Dane
Plant: Soybean
Disease/Disorder: Brown Stem Rot
Pathogen: Phialophora gregata
Counties: Columbia, Racine
Plant: Soybean
Disease/Disorder: Sudden Death Syndrome
Pathogen: Neocosmospora phaseoli
Counties: Columbia, Green Lake, Racine
Forage Crops
No New Diseases
Fruit Crops
Plant: Apple
Disease/Disorder: Fire Blight
Pathogen: Erwinia amylovora
County: Sawyer
Plant: Apple
Disease/Disorder: Flyspeck
Pathogen: Zygophiala jamaicensis
County: La Crosse
Plant: Apple
Disease/Disorder: Frogeye Leaf Spot
Pathogen: Botryosphaeria obtusa
County: La Crosse
Plant: Apple
Disease/Disorder: Gymnosporangium Rust
Pathogen: Gymnosporangium sp.
County: La Crosse
Plant: Apple
Disease/Disorder: Honeycrisp Leaf Mottle
Pathogen: None
Counties: La Crosse, Sawyer
Plant: Apple
Disease/Disorder: Marssonina Leaf Blotch
Pathogen: Marssonina coronaria
County: La Crosse
Plant: Apple
Disease/Disorder: Powdery Mildew
Pathogen: Oidium sp.
County: Sawyer
Plant: Apple
Disease/Disorder: Sooty Blotch
Pathogen: Zygophiala jamaicensis
County: La Crosse
Plant: Strawberry
Disease/Disorder: Root Rot
Pathogen: Cylindrocarpon sp.
County: Columbia
Herbaceous Ornamentals
Plant: Chrysanthemum
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Dodge
Plant: Coleus
Disease/Disorder: Downy Mildew
Pathogen: Peronospora choii
County: Jefferson
Plant: Echinacea
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: Echinacea
Disease/Disorder: Leafy Gall
Pathogen: Rhodococcus facians
County: Ottawa (MI)
Plant: False Indigo
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: False Indigo
Disease/Disorder: Leafy Gall
Pathogen: Rhodococcus facians
County: Ottawa (MI)
Plant: Fan Flower
Disease/Disorder: Root Rot
Pathogen: Phytophthora sp., Pythium sp.
County: Bayfield
Plant: Penstemon
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: Penstemon
Disease/Disorder: Leafy Gall
Pathogen: Rhodococcus facians
County: Ottawa (MI)
Plant: Phlox
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: Phlox
Disease/Disorder: Leafy Gall
Pathogen: Rhodococcus facians
County: Ottawa (MI)
Plant: Yarrow
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: Yarrow
Disease/Disorder: Leafy Gall
Pathogen: Rhodococcus facians
County: Ottawa (MI)
Houseplants
No New Diseases
Needled Woody Ornamentals
Plant: Arborvitae
Disease/Disorder: Phyllosticta Canker
Pathogen: Phyllosticta sp.
County: Waukesha
Plant: Fir
Disease/Disorder: Cytospora Canker
Pathogen: Cytospora sp.
County: Dane
Plant: Fir
Disease/Disorder: Fertility Issues (Suspected)
Pathogen: None
County: Dane
Plant: Pine (White)
Disease/Disorder: Phomopsis Canker
Pathogen: Phomopsis sp.
County: Dane
Vegetable Crops
Plant: Beet
Disease/Disorder: Cercospora Leaf Spot
Pathogen: Cercospora beticola
County: Columbia
Plant: Cabbage
Disease/Disorder: Black Rot
Pathogen: Xanthomonas campestris pv. campestris
County: Waushara
Plant: Cabbage
Disease/Disorder: Fusarium Head Rot
Pathogen: Fusarium sp.
County: Waushara
Plant: Cantaloupe
Disease/Disorder: Alternaria Leaf Blight
Pathogen: Alternaria cucumerina
County: Grant
Plant: Onion
Disease/Disorder: Sour Skin (Suspected)
Pathogen: Burkholderia cepacia
County: Marquette
Plant: Onion
Disease/Disorder: Stemphylium Leaf Blight
Pathogen: Stemphylium sp.
County: Marquette
Plant: Potato
Disease/Disorder: Bacterial Soft Rot
Pathogen: Dickeya dianthicola, Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum, Pectobacterium parmentieri
Counties: Adams, Portage, Waushara
Plant: Potato
Disease/Disorder: Black Dot
Pathogen: Colletotrichum coccodes
County: Waushara
Plant: Potato
Disease/Disorder: Leak
Pathogen: Pythium sp.
County: Portage
Plant: Tomato
Disease/Disorder: Root Rot
Pathogen: Pythium sp.
County: Vilas
Specialty Crops
No New Diseases
Miscellaneous
No New Entries