Plant Problems to Watch for in 2024

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UW Plant Disease Facts

 

Authors:   Brian Hudelson, UW-Madison Plant Pathology
Last Revised:   04/27/2024
D-number:   D0135
 

Conifer - Winter Injury

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 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 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 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 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  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 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 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
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 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 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:

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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.

Submit additional lawn, landscape, and gardening questions at https://hort.extension.wisc.edu/ask-a-gardening-question/.