Downy Mildew

Jim Olis* and Brian Hudelson, UW-Madison Plant Pathology *Completed as partial fulfillment of the requirements for a BS in Plant Pathology at the University of Wisconsin Madison. Revised:  8/6/2012 Item number:  XHT1077 What is downy mildew? The downy mildews are a group of fungal diseases that cause destruction of the leaves, stems, flowers and fruits […]

Bacterial Wetwood

Mary Francis Heimann, O.S.F., Distinguished Outreach Specialist emerita at the University of Wisconsin-Madison and Brian Hudelson, UW-Madison Plant Pathology Revised:  8/13/2012 Item number:  XHT1193 What is bacterial wetwood? Bacterial wetwood, also known as “slime flux”, is a visually frightening-looking, but typically non-lethal, disorder of many types of deciduous trees. This disorder can reduce the aesthetic […]

Apple Scab

Brian Hudelson, UW-Madison Plant Pathology Revised:  11/19/2018 Item number:  XHT1007 What is apple scab?  Apple scab is a potentially serious fungal disease of ornamental and fruit trees in the rose family.  Trees that are most commonly and severely affected include crabapple, hawthorn, mountain-ash, apple and pear.  In ornamental trees, leaf loss caused by apple scab […]

Root and Crown Rots

Brian Hudelson, UW-Madison Plant Pathology and Laura Jull, UW-Madison Horticulture Revised:  8/13/2012 Item number:  XHT1070 What is root/crown rot? Root/crown rot is a general term that describes any disease of woody ornamentals where the pathogen (causal organism) attacks and leads to the deterioration of a plant’s root system and/or lower trunk or branches near the […]

Tar Spot of Trees and Shrubs

Authors: Brian Hudelson, UW-Madison Plant Pathology Last Revised: 12/17/2018 X-number: XHT1126 What is tar spot?   Tar spot is a common, visually distinctive and primarily cosmetic fungal leaf spot disease.  Tar spot can affect many species of maple, including (but not limited to) silver maple, sugar maple and Norway maple.  Boxelder (also known as ash-leaved maple), willow, holly and […]

Purple Bordered Leaf Spot

Barrett Gruber*, Courtney E. Jahn*, Glen Stanosz and Brian Hudelson, UW-Madison Plant Pathology *Completed as partial fulfillment of the requirements for the graduate course: “Plant Pathology 559: Diseases of Economic Crops.” Revised:  8/13/2012 Item number:  XHT1149 What is purple-bordered leaf spot? Purple-bordered leaf spot (also called eye spot or Phyllosticta leaf spot) is a common, […]

Oak Wilt

Jim Olis* and Brian Hudelson, UW-Madison Plant Pathology *Completed as partial fulfillment of the requirements for a BS in Plant Pathology at the University of Wisconsin Madison. Revised:  8/13/2012 Item number:  XHT1075 What is oak wilt? Oak wilt is a lethal fungal disease that affects virtually all species of oaks.  Oaks in the red oak […]

Herbicide Damage

Brian Hudelson, UW-Madison Plant Pathology Revised:  5/11/2010 Item number:  XHT1004 What is herbicide damage?  Herbicide damage is any adverse, undesired effect on a plant that is caused by exposure of that plant to a pesticide designed for weed control (i.e., a herbicide).  Any plant can be subject to this problem.   What does herbicide damage […]

Gray Mold (Botrytis Blight)

Jeffory Schraufnagel*, Milwaukee Area Technical College, Brian Hudelson, UW-Madison Plant Pathology Revised:  5/11/2010 Item number:  XHT1122 What is gray mold?  Gray mold (or Botrytis blight) is a common and often serious fungal disease that can affect plants of all kinds.  Gray mold is a particularly serious problem on flowering plants and those plants grown in […]

Guignardia Leaf Spot

Brian Hudelson, UW-Madison Plant Pathology, UW-Extension Revised:  4/28/2012 Item number:  XHT1123 What is Guignardia leaf spot?  Guignardia leaf spot is a common fungal leaf spot that affects vining plants such as Boston ivy and Virginia-creeper.  The pathogen that causes Guignardia leaf spot also causes a leaf spot and fruit rot of grape called black rot. […]

Golden Canker (Cryptodiaporthe Canker)

Brian Hudelson, UW-Madison Plant Pathology, UW-Extension Revised:  8/6/2012 Item number:  XHT1125 What is golden canker? Golden canker (officially Cryptodiaporthe canker) is a visually distinct and increasingly common disease of alternate-leafed dogwoods such as pagoda dogwood. This disease can potentially be lethal if infections occur on the main trunk of a tree. What does golden canker […]

Dutch Elm Disease

Jim Olis* and Brian Hudelson, UW-Madison Plant Pathology *Completed as partial fulfillment of the requirements for a BS in Plant Pathology at the University of Wisconsin Madison. Revised:  8/6/2012 Item number:  XHT1076 What is Dutch elm disease? Dutch elm disease is a lethal fungal disease of native North American elms.  The fungi that cause Dutch […]

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