Host: Chinese juniper, apple, crabapple
Pathogen: Gymnosporangium yamadae
Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper), red leaf spots (apple, crabapple)
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
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
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
Pathogen: Septoria sp.
Signs/Symptoms: Dead spots on leaves, potentially leading to complete leaf browning
Hosts: Woody and herbaceous ornamentals, vegetables
Pathogens: Verticillium sp.
Signs/Symptoms: Wilting, branch dieback, plant death
For more information see: UW Plant Disease Facts D0121/D0122
Hosts: Herbaceous and woody ornamentals, fruit, vegetables, turf
Pathogens: miscellaneous powdery mildew fungi
Signs/Symptoms: Powdery white growth on leaves
For more information see: UW Plant Disease Facts D0084/86/87
|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
|Diplodia Shoot Blight and Canker
Hosts: Austrian pine, other pines
Pathogen: Diplodia spp.
Signs/Symptoms: Dieback of brand tips with dead needles showing uneven lengths
For more information see: UW Plant Disease Facts D0042
Hosts: Pin oak, red maple, birch, azalea, white pine, blueberry
Signs/Symptoms: Yellow leaves with dark green veins
For more information see: UW Plant Disease Facts D0030
Hosts: Woody trees and shrubs
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 https://pddc.wisc.edu/ or contact your county Extension agent.
© 2022 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 Diana Alfuth, Lisa Johnson 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), and Marissa Wilmot (Septoria leaf spot of lilac) 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.