Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 04/18/2025
D-number: D0136
Scab (Apple and Pear) Hosts: Apple, crabapple, pear, mountain-ash Pathogens: Venturia inaequalis, Venturia pirina Signs/Symptoms: Feathery-edged spots on leaves and fruits often leading to leaf loss and tree defoliation For more information see: UW Plant Disease Facts D0004
Septoria Leaf Spot of Lilac Host: Lilac Pathogen: Septoria sp. Signs/Symptoms: Dead spots on leaves, potentially leading to complete leaf browning
Aster Yellows Hosts: Many herbaceous ornamentals and vegetables Pathogens: Aster yellows phytoplasma Signs/Symptoms: Yellow/orange/purple leaves, stunted and distorted growth, leafy flowers, brooming For more information see: UW Garden Facts D0007
Gymnosporangium Rusts Hosts: Juniper, apple, crabapple, hawthorn, quince Pathogen: Gymnosporangium spp. Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper); yellow/orange leaf spots (other hosts) For more information see:UW Plant Disease Facts D0058/0131
Winter Injury/Winter Burn Hosts: All conifers, particularly yew and juniper Cause: Insufficient water Signs/Symptoms: Needle browning/bleaching over winter or in spring as plants come out of dormancy For more information see: UW Plant Disease Facts D0127
Bacterial Canker Hosts: Stone fruits (cherry, peach, plum) Pathogen: Pseudomonas syringae Signs/Symptoms: Masses of sap on affected branches/trunks, branch die back, tree death For more information see:UW Plant Disease Facts D0009
Powdery Mildew Hosts: Herbaceous and deciduous woody ornamentals, fruits, 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
Septoria Leaf Spot and Early Blight Host: Tomato Pathogens: Septoria lycopersici and Alternaria solani Signs/Symptoms: Spotting and eventual total death of leaves working from the bottom of the plant up For more information see: UW Plant Disease Facts D0100/46
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
Chlorosis Hosts: Pin oak, red maple, birch, azalea, white pine, blueberry Pathogen: None (Abiotic) Signs/Symptoms: Yellow leaves with dark green veins For more information see: UW Plant Disease Facts D0030
For more information on plant problems to watch for in 2025: Contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu. This Fact Sheet is also available in PDF format:
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, Kathy Johnson and Margaret Murphy for reviewing this document.
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.
Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 04/27/2024
D-number: D0135
Winter Injury/Winter Burn Hosts: All conifers, particularly yew and juniper Cause: Insufficient water Signs/Symptoms: Needle browning/bleaching over winter or in spring as plants come out of dormancy For more information see: UW Plant Disease Facts D0127
Chlorosis Hosts: Pin oak, red maple, birch, azalea, white pine, blueberry Pathogen: None (Abiotic) Signs/Symptoms: Yellow leaves with dark green veins For more information see: UW Plant Disease Facts D0030
Blister Canker Hosts: Apple, crabapple, serviceberry, mountain-ash Pathogen: Biscogniauxia marginata Signs/Symptoms: Dark, sunken, cracked areas on trunks with dark, round, flat pads of fungal growth For more information see: UW Plant Disease Facts D0134
Golden Canker Hosts: Pagoda dogwood Pathogen:Cryptodiaporthe corni Signs/Symptoms: Dead branches that are gold in color, often with orange spots For more information see: UW Plant Disease Facts D0055
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
Fire Blight Hosts: Apple, crabapple, pear, mountain-ash Pathogen: Erwinia amylovora Signs/Symptoms: Branch dieback (often with the tip having a shepherd’s crook), eventual tree death For more information see: UW Plant Disease Facts D0052
Cucumber Mosaic Hosts: Herbaceous ornamentals and vegetables Pathogens: Cucumber mosaic virus Signs/Symptoms: Blotchy light and dark green leaf color, distorted leaf growth For more information see: UW Plant Disease Facts D0036
Powdery Mildew 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
Red Star Rust Red Star Rust Hosts: Chinese juniper, apple, crabapple Pathogen:Gymnosporangium yamadae Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper), red leaf spots (apple, crabapple) For more information see: UW Plant Disease Facts D0131
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
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 in 2024: Contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.This Fact Sheet is also available in PDF format:
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).
References to pesticide products in this publication are for your convenience and are not an endorsement or criticism of one product over similar products. You are responsible for using pesticides according to the manufacturer’s current label directions. Follow directions exactly to protect the environment and people from pesticide exposure. Failure to do so violates the law.
Thanks to Julie Hill, Margaret Murphy and Denise Rocha for reviewing this document.
Thanks also to Serenella Linares (blister canker), Nancy Gregory-University of Maryland (lipstick rust), and David Clement (boxwood blight) 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.
Authors: Brian Hudelson UW-Madison Plant Pathology
Last Revised: 03/01/2024
D-number: D0132
Lipstick Rust
Host: Chinese juniper, apple, crabapple
Pathogen: Gymnosporangium yamadae
Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper), red leaf spots (apple, crabapple)
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
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
Verticillium Wilt 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
Powdery Mildew
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
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 https://pddc.wisc.edu/ or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.
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.
Authors: Brian Hudelson UW-Madison Plant Pathology
Last Revised: 03/01/2024
D-number: D0132
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 Diseases 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 D0084
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 https://pddc.wisc.edu/ or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.
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.
Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 03/02/2024
D-number: D0120
Septoria Leaf Spot and Early Blight Host: Tomato Pathogens: Septoria lycopersicia 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 Garden Facts D0100/D0046
Late Blight Hosts: 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 Garden Facts D0068
Blossom End Rot Host: Tomato, pepper, eggplant, cucumber, squash Cause: Calcium deficiency Signs/Symptoms: Decayed areas on the bottom sides of vegetable fruits For more information see: UW Garden Facts D0022
Powdery Mildew Hosts: Any vegetable, particularly vine crops, peas Pathogens: Miscellaneous powdery mildew fungi Signs/Symptoms: Powdery white growth on leaves For more information see: UW Garden Facts D0086
Common Corn Smut Hosts: Corn Pathogen: Ustilago maydis Signs/Symptoms: Pasty white masses on corn ears eventually decomposing into a brown powder For more information see: UW Garden Facts D0031
Black Rot Hosts: Crucifers (e.g., cabbage, broccoli, cauliflower) Pathogen: Xanthomonas campestris pv. campetris Signs/Symptoms: V-shaped yellow/dead areas on leaves progressing into plant deterioration and death For more information see: UW Garden Facts D0019
Potato Scab Hosts: Potato, carrot, beet, other root crops Pathogen: Streptomyces scabies Signs/Symptoms: Brown, rough, scab-like areas on tubers and roots For more information see: UW Garden Facts D0083
Verticillium Wilt Host: Tomato, pepper, eggplant, potato, vine crops Pathogen: Verticillium spp. Signs/Symptoms: Leaf yellowing and wilting of plants followed by eventual plant death For more information see: UW Garden Facts D0122
Aster Yellows Hosts: Carrot Pathogens: Aster yellows phytoplasma Signs/Symptoms: Yellow/orange/purple leaves, stunted roots with tufts of white hairy roots For more information see: UW Garden Facts D0007
Bacterial Wilt Hosts: Vine crops Pathogen: Erwinia tracheiphila Signs/Symptoms: Sectional wilting and eventual death of plants after cucumber beetle feeding For more information see: UW Garden Facts D0014
Basil Downy Mildew Host: Basil Pathogen: Peronospora belbahrii Signs/Symptoms: Downward-cupped, yellow leaves with purple-gray fuzz on leaf undersurfaces For more information see: UW Garden Facts D0015
For more information on vegetable diseases:
See https://pddc.wisc.edu/ or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.
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 Jane Anklam, Vijai Pandian, and Linda Remeschatis for reviewing this document. Thanks also to Amanda Gevens (late blight, black rot, Verticillium wilt), ISU-PIDC (bacterial wilt) and Debbie Roos (basil downy mildew) 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.
Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 03/01/2024
D-number: D0081
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
Late Blight Hosts: 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 of Lilac Host: Lilac Pathogen: Septoria sp. Signs/Symptoms: Dead spots on leaves, potentially leading to complete leaf browning
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
Gymnosporangium Rusts Hosts: Juniper, apple, crabapple, hawthorn, quince Pathogen: Gymnosporangium spp. Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper); yellow/orange leaf spots (other hosts) For more information see: UW Plant Disease Facts D0058
Elderberry Rust Hosts: Elderberry Pathogen: Puccinia sambuci Signs/Symptoms: Light yellow, powdery growths on branches For more information see: UW Plant Disease Facts D0049
Scab (Apple and Pear) Hosts: Apple, crabapple, pear, mountain-ash Pathogens: Venturia inaequalis, Venturia pirina Signs/Symptoms: Feathery-edged spots on leaves and fruits often leading to leaf loss and tree defoliation For more information see: UW Plant Disease Facts D0004
Bur Oak Blight Host: Bur oak Pathogen: Tubakia iowensis Signs/Symptoms: Wedge-shaped dead areas on leaves leading to dead leaves that stay attached to trees
Powdery Mildew Hosts: Herbaceous and woody ornamentals, fruits, 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
Diplodia Shoot Blight and Canker Hosts: Austrian pine, other pines Pathogen: Diplodia spp. Signs/Symptoms: Dieback of branch tips with dead needles showing uneven lengths For more information see: UW Plant Disease Facts D0042
Boxwood Blight Host: Boxwood Pathogen: Calonectria pseudonaviculata Signs/Symptoms: Circular, brown leaf spots followed by leaf drop and shrub death For more information see: UW Plant Disease Facts D0023
For more information on plant diseases to watch for:
See https://pddc.wisc.edu/ or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.
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, Margaret Murphy and Denise Worzalla-Rocha for reviewing this document. Thanks also to Amanda Gevens (late blight), Marissa Wilmot (Septoria leaf spot of lilac), Jenell Bindl (elderberry rust), Lina Rodriguez-Salamanca (bur oak blight) and David Clement (boxwood blight) 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.
Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 03/02/2024
D-number: D0112
Powdery Mildew Hosts: Herbaceous and woody ornamentals, fruits, 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
Tar Spot Hosts: Maples Pathogen: Rhytisma spp. Signs/Symptoms: Tarry areas (either solid spots or clusters of small spots) on leaves For more information see: UW Plant Disease Facts D0110
Peach Leaf Curl Hosts: Peach Pathogen: Taphrina deformans Signs/Symptoms: Light-green, yellow or purplish-red puckered areas on leaves For more information see: UW Plant Disease Facts D0076
Sooty Mold Hosts: Any plant Pathogen: Miscellaneous sooty mold fungi Signs/Symptoms: Powdery black growth on leaves or needles For more information see: UW Bulletin A2637
Chlorosis Hosts: Oak, red maple Cause: Iron or manganese deficiency, often induced by high soil pH Signs/Symptoms: Yellow leaves with dark green veins For more information see: UW Plant Disease Facts D0030
Gymnosporangium Rusts Hosts: Juniper, apple, crabapple, hawthorn, quince Pathogen: Gymnosporangium spp. Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper); yellow/orange leaf spots (other hosts) For more information see: UW Plant Disease Facts D0058
Black Knot Hosts: Prunus spp. (plum and cherry) Pathogen: Apiosporina morbosa Signs/Symptoms: Black poop-like growths on branches For more information see: UW Plant Disease Facts D0018
Elderberry Rust Hosts: Elderberry Pathogen: Puccinia sambuci Signs/Symptoms: Light yellow, powdery growths on branches For more information see: UW Plant Disease Facts D0049
Golden Canker Hosts: Pagoda dogwood Pathogen: Cryptodiaporthe corni Signs/Symptoms: Gold-colored branches with orange spots For more information see: UW Plant Disease Facts D0055
Dog Vomit Slime Mold Hosts: Any plant and on mulch Cause:Fuligo septica Signs/Symptoms: Scrambled egg-like masses on mulch or at the base of plants For more information see: UW Plant Disease Facts D0102
For more information on common plant diseases:
See https://pddc.wisc.edu/ or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.
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, Mike Maddox and Ann Wied for reviewing this document.
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.
Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 02/29/2024
D-number:D0041
Anthracnose Hosts: Most trees, commonly ash, maple and oak Pathogens:Gloeosporium spp. as well as other fungi Signs/Symptoms: Blotchy dead areas on leaves For more information see: UW Plant Disease Facts D0002
Purple-Bordered Leaf Spot Host: Amur, Japanese, red, silver and sugar maple Pathogen:Phyllosticta minima Signs/Symptoms: Discrete, circular leaf spots with purple borders For more information see: UW Plant Disease Facts D0089
Tubakia (Actinopelte) Leaf Spot Hosts: Oak Pathogen:Tubakia spp. (Actinopelte spp.) Signs/Symptoms: Discrete circular, or irregular blotchy dead areas on leaves For more information see: UW Plant Disease Facts D0118
Apple Scab Hosts: Apple, crabapple, pear, mountain-ash Pathogen:Venturia inaequalis, V. pirina Signs/Symptoms: Circular, black leaf spots with feathery edges; eventual leaf loss For more information see: UW Plant Disease Facts D0004
Gymnosporangium Rusts Hosts: Apple, crabapple, hawthorn Pathogens: Gymnosporangium spp. Signs/Symptoms: Bright yellow-orange, circular leaf spots For more information see: UW Plant Disease Facts D0058
Powdery Mildew Hosts: Most deciduous trees Pathogens: Several genera of powdery mildew fungi Signs/Symptoms: Uniform/blotchy powdery white areas on upper and lower leaf surfaces For more information see: UW Plant Disease Facts D0087
Downy Leaf Spot Hosts: Hickory, walnut Pathogen:Microstroma juglandis Signs/Symptoms: Discrete powdery white areas on lower leaf surfaces
Chlorosis Hosts: Oak, red maple Cause: Iron or manganese deficiency, often induced by high soil pH Signs/Symptoms: Yellow leaves with dark green veins For more information see: UW Plant Disease Facts D0030
Scorch Hosts: Most deciduous trees Cause: Water stress induced by drought, high soil salt content, or other water-limiting factors Signs/Symptoms: Dead tissue on leaf margins
Tatters Hosts: Most deciduous trees, but commonly oak Cause: Possible early season cold injury Signs/Symptoms: Lacy, tattered-looking leaves For more information see: UW Plant Disease Facts D0111
For more information on deciduous tree leaf diseases:
See https://pddc.wisc.edu/ or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.
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, Kristin Krokowski, and Patti Nagai for reviewing this document, and to Matt Hanson for supplying the powdery mildew photo
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.
Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 02/29/2024
D-number: D0033
Root and Crown Rots Hosts: All conifers Pathogens: Assorted root rot fungi/water molds Signs/Symptoms: Poor growth, branch dieback, discolored and deteriorated roots For more information see: UW Plant Disease Facts D0094
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
Cytospora Canker Hosts: Colorado blue spruce, other spruces Pathogen: Cytospora kunzei Signs/Symptoms: Branch dieback with milky-white patches of dried sap on affected branches For more information see: UW Plant Disease Facts D0037
Spruce Needle Drop Hosts: Spruces Pathogen: Unknown (possibly Setomelannoma holmii) Signs/Symptoms: Needle loss and dieback at or near branch tips
Gymnosporangium Rusts Hosts: Juniper, apple, crabapple, hawthorn, quince Pathogen: Gymnosporangium spp. Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper); yellow/orange leaf spots (other hosts) For more information see: UW Plant Disease Facts D0058
Phomopsis Tip Blight Hosts: Junipers Pathogen: Phomopsis juniperovora Signs/Symptoms: Browning and dieback of branch tips in spring and early summer as new growth emerges For more information see: UW Plant Disease Facts D0077
Diplodia Shoot Blight and Canker Hosts: Austrian pine, other pines Pathogen: Diplodia spp. Signs/Symptoms: Dieback of branch tips with dead needles showing uneven lengths For more information see: UW Plant Disease Facts D0042
Dothistroma Needle Blight Hosts: Austrian pine, other pines Pathogen: Dothistroma pini Signs/Symptoms: Needle tip browning and death with a distinct break between live and dead tissue For more information see: UW Plant Disease Facts D0043
Drought Stress Hosts: All conifers Cause: Insufficient water Signs/Symptoms: Purpling/browning of needles near branch tips or higher up in plants during the summer
Winter Injury/Winter Burn Hosts: All conifers, particularly yew and juniper Cause: Insufficient water Signs/Symptoms: Needle browning/bleaching over winter or in spring as plants come out of dormancy For more information see: UW Plant Disease Facts D0127
Herbicide Damage Hosts: All conifers Cause: Exposure to herbicides Signs/Symptoms: Twisted or otherwise distorted growth, needle yellowing or browning, plant death For more information see: UW Plant Disease Facts D0060
For more information on conifer diseases:
See https://pddc.wisc.edu/ or contact the University of Wisconsin Plant Disease Diagnostics Clinic (PDDC) at (608) 262-2863 or pddc@wisc.edu.
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 Ann Joy, Patti Nagai and Ann Wied for reviewing this document and to Bria Radtke for supplying the photo of spruce needle drop.
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.
Authors: P.J. Liesch, UW-Madison Plant Pathology; Vijai Pandian, UW-Extension Brown County; and Jim Kerns, formerly of UW-Madison Plant Pathology
Last Revised: 03/01/2024
D-number: D0069
Snow Mold
Snow Molds
(Microdochium nivale and Typhula spp.)
Occurrence: Early to late spring Favorable Conditions: Cold wet weather with periods of prolonged snow cover over unfrozen ground often leading to the most severe damage Hosts: Kentucky bluegrass, tall fescue, perennial ryegrass Symptoms: Circular, matted, gray to straw-colored patches ranging from a few inches to a foot or more in diameter Management: Remove leaf litter from lawns. Mow lawns until dormant in the fall. Avoid heavy fertilizer applications (greater than 0.5 lb. N/1,000 sq. ft.) late in the year. Rake and lightly fertilize damaged areas in the spring to encourage recovery. Reseed lawns as needed.
Necrotic Ring Spot
Necrotic Ring Spot
(Ophiosphaerella korrae)
Occurrence: Spring, summer and fall Favorable Conditions: Cool (soil temperatures of 55 to 65oF) and wet conditions for infection, followed by heat and drought stress for symptom development; most severe when soil compaction limits rooting Host: Kentucky bluegrass Symptoms: Circular, straw-colored patches usually less than 12 inches in diameter; regrowth often occurring in the center of patches, creating a “frog-eye” appearance; most common in newly sodded lawns, but also occurring in seeded lawns Management: Reduce soil compaction and improve lawn drainage. Maintain proper fertility.
Fairy Ring
Fairy Rings (many mushroom-forming fungi)
Occurrence: Anytime Favorable conditions: Warm, wet weather; significant thatch accumulation Hosts: All cool-season lawn grasses Symptoms:Type I: a ring or arc (up to several feet in diameter) of lush, dark green grass bordered by a band of dead turf, with or without mushrooms; Type II: a ring or arc of lush dark green grass with no band of dead turf, with or without mushrooms; Type III: a ring or arc of mushrooms with no band of lush green turf or dead turf Management: Lightly fertilize and routinely core aerate lawns.
Summer Patch
Summer Patch (Magnaporthiopsis poae)
Occurrence: Summer Favorable conditions: Hot, moist conditions; alkaline (i.e., high) soil and thatch pH Hosts: Kentucky bluegrass, fine fescues Symptoms: Ring-like patches of wilted turf up to 3 inches in diameter, similar to those of necrotic ring spot (see above), and with rings often merging into larger irregular patches Management: Avoid excessive watering during hot periods. Core aerate to promote root growth and reduce compaction. Use acidifying fertilizers to lower thatch pH to below 6.5.
Dollar Spot
Dollar Spot (Clarireedia jacksonii)
Occurrence: Summer Favorable conditions: High humidity; low nitrogen fertility Hosts: Kentucky bluegrass, perennial ryegrass, fine fescues Symptoms: Bleached patches ranging from a few inches to a foot in diameter, with leaf blades (inset) having bleached, hourglass-shaped areas Management: Water deeply and infrequently early in the morning to minimize prolonged periods of leaf wetness. Apply nitrogen to alleviate symptoms.
Red Thread
Red Thread (Laetisaria fuciformis)
Occurrence: Spring through fall Favorable conditions: Wet, cool conditions Hosts: Kentucky bluegrass, perennial ryegrass, fine fescues Symptoms: Irregular beige patches ranging from a few inches to a few feet in diameter (oftentimes merging into irregular patterns) with red, thread-like filaments among the grass blades Management: Collect clippings when disease is active. Maintain adequate nitrogen fertility.
Rust
Rust (Puccinia spp., Uromyces spp.)
Occurrence: Summer and fall Favorable conditions: High humidity, low soil moisture, low nitrogen fertility, shade Hosts: Kentucky bluegrass, perennial ryegrass Stand Symptoms: Reddish-brown, powdery areas (masses of fungal spores) that can discolor clothing and equipment Management: Maximize light and airflow in lawns by pruning and thinning surrounding landscape plants. Water and lightly fertilize.
For more information on lawn diseases:
Contact the University of Wisconsin Turf Diagnostic Lab (TDL) at (608) 845-2535 or hockemeyer@wisc.edu.
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, Doug Soldat and Karen Schleis for reviewing this document.
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.
