Compiled by Brian Hudelson and Hulubanche Kassa

The following diseases/disorders were identified at the Plant Disease Diagnostics Clinic from August 15, 2026 through August 21, 2026.

 

 

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Broad-Leafed Woody Ornamentals

Plant:  Ash (Unspecified)
Disease/Disorder:  Cylindrosporium Leaf Spot
Pathogen:  Cylindrosporium sp.
County:  Eau Claire

Plant:  Crabapple
Disease/Disorder:  Fire Blight
Pathogen:  Erwinia amylovora
Counties:  Eau Claire, Lincoln

Plant:  Lilac
Disease/Disorder:  Septoria Leaf Spot
Pathogen:  Septoria sp.
County:  Waukesha

Plant:  Magnolia
Disease/Disorder:  Root Rot
Pathogen:  Pythium sp.
County:  Waukesha

Plant:  Maple (Unspecified)
Disease/Disorder:  Anthracnose
Pathogen:  Discula sp. 
County:  La Crosse

Plant:  Oak (Red)
Disease/Disorder:  Oak Wilt
Pathogen:  Bretziella fagacearum
County:  Dane

Plant:  Oak (White)
Disease/Disorder:  Chlorosis
Pathogen:  None
County:  Waukesha

Plant:  Oak (White)
Disease/Disorder:  Coryneum Canker
Pathogen:  Coryneum sp.
County:  Waukesha

Plant:  Oak (Unspecified)
Disease/Disorder:  Oak Wilt
Pathogen:  Bretziella fagacearum
Counties:  Brown, Washburn

Plant:  Oak (Unspecified)
Disease/Disorder:  Root Rot
Pathogen:  Phytophthora sp.
County:  Waukesha

Plant:  Rose
Disease/Disorder:  Rose Rosette
Pathogen:  Rose rosette virus
County:  Milwaukee

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Field Crops

Plant:  Corn
Disease/Disorder:  Southern Rust
Pathogen:  Puccinia polysora
County:  Outagamie

Plant:  Soybean
Disease/Disorder:  Anthracnose
Pathogen:  Colletotrichum sp.
County:  Dodge

Plant:  Soybean
Disease/Disorder:  Downy Mildew
Pathogen:  Peronospora manshurica
County:  Dodge

Plant:  Soybean
Disease/Disorder:  Fusarium Root Rot
Pathogen:  Fusarium sp.
County:  Dodge

Plant:  Soybean
Disease/Disorder:  Phytophthora Root and Stem Rot
Pathogen:  Phytophthora sp.
County:  Dodge

Plant:  Soybean
Disease/Disorder:  Stem Canker
Pathogen:  Diaporthe phaseolorum
County:  Dodge

Plant:  Soybean
Disease/Disorder:  Sudden Death Syndrome
Pathogen:  Neocosmospora phaseoli
County:  Sauk

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Forage Crops

No New Diseases

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Fruit Crops

Plant:  Apple (‘Honeycrisp’)
Disease/Disorder:  Honeycrisp Leaf Mottle
Pathogen:  None
County:  Milwaukee

Plant:  Apple (Unspecified)
Disease/Disorder:  Chemical Burn (Suspected)
Pathogen:  None
County:  Milwaukee

Plant:  Apple (Unspecified)
Disease/Disorder:  Frogeye Leaf Spot
Pathogen:  Botryosphaeria obtusa
County:  Dane

Plant:  Grape
Disease/Disorder:  Botryosphaeria Dieback
Pathogen:  Botryosphaeria sp.
County:  Dane

Plant:  Pear
Disease/Disorder:  Bitter Rot
Pathogen:  Colletotrichum sp.
County:  Walworth

Plant:  Strawberry
Disease/Disorder:  Root/Crown Rot
Pathogen:  Rhizoctonia sp., Fusarium sp.
Counties:  Anoka (MN), Dakota (MN)

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Herbaceous Ornamentals

Plant:  Chrysanthemum
Disease/Disorder:  Crown Gall
Pathogen:  Agrobacterium tumefaciens
County:  Clark

Plant:  Daisy (Unspecified)
Disease/Disorder:  Crown Gall
Pathogen:  Agrobacterium tumefaciens
County:  Ottawa (MI)

Plant:  Hosta
Disease/Disorder:  Sunburn (Suspected)
Pathogen:  None
County:  Milwaukee

Plant:  Hosta
Disease/Disorder:  Tobacco Rattle
Pathogen:  Tobacco rattle virus
County:  Buffalo

Plant:  Little Bluestem
Disease/Disorder:  Curvularia Blight
Pathogen:  Curvularia sp.
County:  Rock

Plant:  Little Bluestem
Disease/Disorder:  Helminthosporium Leaf Spot
Pathogen:  Helminthosporium sp.
County:  Rock

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Houseplants

No New Diseases

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Needled Woody Ornamentals

Plant:  Juniper
Disease/Disorder:  Root Rot
Pathogen:  Phytophthora sp.
County:  Waukesha

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Vegetable Crops

Plant:  Onion
Disease/Disorder:  Stemphylium Leaf Blight
Pathogen:  Stemphylium sp.
County:  Dane

Plant:  Potato
Disease/Disorder:  Bactieral Soft Rot
Pathogen:  Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum, Pectobacterium parmentieri
Counties:  Dane, Waushara

Plant:  Potato
Disease/Disorder:  Black Scurf
Pathogen:  Rhizoctonia solani
County:  Adams

Plant:  Potato
Disease/Disorder:  Fusarium Dry Rot
Pathogen:  Fusarium sp.
Counties:  Adams, Dane  

Plant:  Potato
Disease/Disorder:  Pythium Leak
Pathogen:  Pythium sp.
County:  Dane

Plant:  Tomato (Cherry)
Disease/Disorder:  Bacterial Canker
Pathogen:  Clavibacter michiganensis subsp. michiganensis
County:  Boone (IL)

Plant:  Tomato (Unspecified)
Disease/Disorder:  Bacterial Canker
Pathogen:  Clavibacter michiganensis subsp. michiganensis
County:  Dane

Plant:  Tomato (Unspecified)
Disease/Disorder:  Septoria Leaf Spot
Pathogen:  Septoria lycopersici
County:  Dane

Plant:  Tomato (Unspecified)
Disease/Disorder:  Verticillium Wilt
Pathogen:  Verticillium sp.
County:  Dane

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Specialty Crops

Plant:  Peppermint
Disease/Disorder:  Verticillium Wilt
Pathogen:  Verticillium sp.
County:  Rock

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Miscellaneous

No New Entries

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