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 […]

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 […]


Brian Hudelson, UW-Madison Plant Pathology, UW-Extension Revised:  1/8/2012 Item number:  XHT1002 What is chlorosis?  Chlorosis is a common nutritional disorder of many woody ornamentals in Wisconsin, particularly in the southern and eastern parts of the state.  Pin oaks are most commonly affected by chlorosis, although many other trees and shrubs (e.g., white oak, red maple, […]

Gymnosporangium Rusts

Authors: Brian Hudelson, UW-Madison Plant Pathology Last Revised: 01/23/2019 X-number: XHT1009 What are Gymnosporangium rusts? Gymnosporangium rusts are a group of closely related diseases caused by fungi that infect both junipers (in particular red cedar) and woody plants in the rose family (such as, but not limited to, apple, crabapple, hawthorn and quince). These fungi […]

Bacterial Blight

Gina Foreman* and Brian Hudelson, UW-Madison Plant Pathology *Completed as partial fulfillment of the requirements for Plant Pathology 875 – Plant Disease Diagnostics Clinic Internship at the University of Wisconsin Madison. Revised:  4/25/2004 Item number:  XHT1093 What is bacterial blight?  Bacterial blight, also known as blossom blight or shoot blight, is a common and often […]

Black Knot

Brian Hudelson, UW-Madison Plant Pathology, UW-Extension Revised:  5/1/2010 Item number:  XHT1056 What is black knot?  Black knot is a disfiguring and potentially lethal disease of trees and shrubs in the genus Prunus.  This genus includes stone fruits such as wild, fruit-bearing and ornamental plums and cherries. What does black knot look like?  During the first […]

Damping Off

Brian Hudelson, UW-Madison Plant Pathology Revised:  4/25/2004 Item number:  XHT1124 What is damping-off?  Damping-off is a common and fatal disease that affects all types of plant seedlings.  The disease is most prevalent when seeds are germinated in cool, wet soils.  Fortunately, seedlings are susceptible to damping-off for only a short period following emergence and eventually […]

Spotted Tentiform Leafminer, Phyllonorycter blancardella

Have you had people ask what those funny stippled blotches on their apple tree leaves are? When held up to the light, the spotted nature of these mines become apparent, and are a diagnostic feature of the damage caused by the spotted tentiform leafminer. If you want to learn more about this insect pest, read this article…


Are you interested in getting higher yields of fruit, want a fruit tree but don’t have space for a regular-sized one, or just want an interesting pruned plant as a focal point in your garden? There is a horticultural technique involving pruning and training that can accomplish all of these goals. Read this article to learn more about the classic technique of espalier…

Split-leaf philodendron, Monstera deliciosa

It’s a tropical plant native to rainforests of Central America that is often grown as a foliage houseplant. With big holes in its leaves, it’s aptly called Swiss cheese plant, but is more commonly known as split-leaf philodendron. Did you know it also has edible fruits? Learn more about Monstera deliciosa in this article…

Apple Maggot: Scourge of Home Apple Production

If you have an apple tree in your backyard, you’ve probably found out that apple maggot likes your fruit as much as you do. Learn from UW-Extension Fruit Entomologist Dan Mahr more about this pesky fly and what to do about it in this article…

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