Boxwood Blight
Host: Boxwood
Pathogens: Calonectria pseudonaviculata
Signs/Symptoms: Circular, brown leaf spots followed by leaf drop and shrub death
For more information see: UW Plant Disease Facts D0023
Lipstick Rust
Host: Chinese juniper, apple, crabapple
Pathogen: Gymnosporangium yamadae
Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper), red leaf spots (apple, crabapple)
Late Blight
Host: Tomato, potato
Pathogen: Phytophthora infestans
Signs/Symptoms: Water-soaked spots on leaves, leathery areas on tomato fruits, rapid plant death
For more information see: UW Plant Disease Facts D0068
Septoria Leaf Spot and Early Blight
Host: Tomato
Pathogens: Septoria lycopersici and Alternaria solani
Signs/Symptoms: Spotting and eventual total collapse of leaves, working from the bottom of the plant up
For more information see: UW Plant Disease Facts D0100/46
Septoria Leaf Spot of Lilac
Host: Lilac
Pathogen: Septoria sp.
Signs/Symptoms: Dead spots on leaves, potentially leading to complete leaf browning
Wood Rots
Hosts: Woody trees and shrubs
Pathogens: Miscellaneous wood rot fungi
Signs/Symptoms: Shelf-like growths on trunks and branches
Canker Diseases
Hosts: Woody trees and shrubs
Pathogens: Miscellaneous canker fungi
Signs/Symptoms: Sunken areas on trunks/branches
For more information see: UW Plant Disease Facts D0027, D0037, D0042, D0055, D0074, D0114
Virus Disaeases
Hosts: All plants, particularly herbaceous ornamentals
Pathogen: Miscellaneous plant viruses
Signs/Symptoms: Blotchy leaf color, growth distortions
For more information see: UW Plant Disease Facts D0036, D0063, D0067, D0115, D0116, D0130
Rhizosphaera Needle Cast
Hosts: Colorado blue spruce, other spruces
Pathogen: Rhizosphaera kalkhoffii
Signs/Symptoms: Browning/purpling of interior needles of lower branches, followed by needle drop
For more information see: UW Plant Disease Facts D0093
Chlorosis
Hosts: Pin oak, red maple, birch, azalea, white pine, blueberry
Pathogen: None
Signs/Symptoms: Yellow leaves with dark green veins
For more information see: UW Plant Disease Facts D0030
Improper Planting
Hosts: Woody trees and shrubs
Pathogen: None
Signs/Symptoms: No root flare at the soil line, girdling roots, frost cracks, canopy thinning, early fall color, branch dieback, tree/shrub decline and death
For more information on plant problems to watch for:
See the UW-Madison Plant Disease Diagnostics Clinic website (https://pddc.wisc.edu/) or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at 608-262-2863 or pddc@wisc.edu.
© 2022-2026 the Board of Regents of the University of Wisconsin System doing business as University of Wisconsin-Madison Division of Extension.
An EEO/Affirmative Action employer, University of Wisconsin-Madison Division of Extension provides equal opportunities in employment and programming, including Title IX and ADA requirements. This document can be provided in an alternative format by calling Brian Hudelson at 608-262-2863 (711 for Wisconsin Relay).
Thanks to Julie Hill, Jeannie Manis and Carol Shirk for reviewing this document. Thanks also to David Clement (boxwood blight), Nancy Gregory-University of Maryland (lipstick rust), Amanda Gevens (late blight), Marissa Wilmot (Septoria leaf spot of lilac), and Diane Malchow (wood rots) for use of their photos.
A complete inventory of UW Plant Disease Facts is available at the University of Wisconsin-Madison Plant Disease Diagnostics Clinic website. (https://pddc.wisc.edu)
Submit additional lawn, landscape, and gardening questions at the Ask a Gardening Question page (https://hort.extension.wisc.edu/ask-a-gardening-question/) of the University of Wisconsin-Madison Division of Extension Horticulture website.