Compiled by Brian Hudelson and Hulubanche Kassa
The following diseases/disorders were identified at the Plant Disease Diagnostics Clinic from September 19, 2026 through September 25, 2026.
Broad-Leafed Woody Ornamentals
Plant: Aspen
Disease/Disorder: Septoria Leaf Spot
Pathogen: Septoria sp. (Sphaerulina sp.)
County: Dane
Plant: Beech (European)
Disease/Disorder: Phomopsis Canker
Pathogen: Phomopsis sp.
County: Milwaukee
Plant: Elm (Unspecified)
Disease/Disorder: Dutch Elm Disease
Pathogen: Ophiostoma sp.
County: Cook (IL)
Plant: Maple (Japanese)
Disease/Disorder: Verticillium Wilt
Pathogen: Verticillium sp.
County: Dane
Plant: Oak (Bur)
Disease/Disorder: Tubakia Leaf Spot
Pathogen: Tubakia sp.
County: Vernon
Plant: Oak (Red)
Disease/Disorder: Oak Wilt
Pathogen: Bretziella fagacearum
County: Brown
Plant: Oak (Unspecified)
Disease/Disorder: Oak Wilt
Pathogen: Bretziella fagacearum
County: Waukesha
Plant: Pear (Ornamental)
Disease/Disorder: Fire Blight
Pathogen: Erwinia amylovora
County: Waukesha
Plant: Willow (Dappled)
Disease/Disorder: Botryosphaeria Canker
Pathogen: Botryosphaeria sp.
County: Dane
Field Crops
Plant: Corn
Disease/Disorder: Gibberella Ear Rot
Pathogen: Gibberella zeae (Fusarium graminearum)
County: Sauk
Plant: Corn
Disease/Disorder: Gray Leaf Spot
Pathogen: Cercospora sp.
County: Sauk
Plant: Corn
Disease/Disorder: Northern Corn Leaf Blight
Pathogen: Exserohilum turcicum
County: Sauk
Plant: Soybean
Disease/Disorder: Cercospora Leaf Blight
Pathogen: Cercospora kikuchii
County: Rusk
Plant: Soybean
Disease/Disorder: Charcoal Rot
Pathogen: Macrophomina phaseolina
County: Jefferson
Plant: Soybean
Disease/Disorder: Fusarium Root Rot
Pathogen: Fusarium sp.
County: Rock
Plant: Soybean
Disease/Disorder: Stem Canker
Pathogen: Diaporthe phaseolorum
County: Jefferson
Forage Crops
No New Diseases
Fruit Crops
Plant: Cranberry
Disease/Disorder: Bitter Rot
Pathogen: Colletotrichum sp.
County: Monroe
Plant: Grape
Disease/Disorder: Black Rot
Pathogen: Guignardia bidwellii
County: Waushara
Herbaceous Ornamentals
Plant: Bluestar (Unspecified)
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: Hosta
Disease/Disorder: Potyvirus Disease
Pathogen: Unspecified potyvirus
County: Pepin
Plant: Indian Plantain (Pale)
Disease/Disorder: Tomato Spotted Wilt
Pathogen: Tomato spotted wilt virus
County: Marquette
Plant: Peony
Disease/Disorder: Root/Crown Rot
Pathogen: Phytophthora sp.
County: Brown
Plant: Sedum
Disease/Disorder: Powdery Mildew
Pathogen: Oidium sp.
County: Washington
Plant: Speedwell (Unspecified)
Disease/Disorder: Crown Gall
Pathogen: Agrobacterium tumefaciens
County: Ottawa (MI)
Plant: Speedwell (Unspecified)
Disease/Disorder: Leafy Gall
Pathogen: Rhodococcus facians
County: Ottawa (MI)
Houseplants
Plant: African Mask Plant
Disease/Disorder: Root/Crown Rot
Pathogens: Phtophthora sp., Fusarium sp.
County: Kenosha
Needled Woody Ornamentals
No New Diseases
Vegetable Crops
Plant: Lettuce
Disease/Disorder: Bacterial Leaf Spot
Pathogen: Xanthomonas sp.
County: Aroostook (ME)
Plant: Potato
Disease/Disorder: Bacterial Soft Rot
Pathogen: Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum
County: Waushara
Plant: Tomatillo
Disease/Disorder: Cercospora Leaf Spot
Pathogen: Cercospora sp.
County: Dane
Specialty Crops
No New Diseases
Miscellaneous
No New Entries