UW Plant Disease Facts

Conifer Disease Quick Reference

Authors: Brian Hudelson, UW-Madison Plant Pathology
Last Revised: 02/29/2008
D-number: XHT1025
Conifer - Root and Crown Rot Root and Crown Rots Hosts: All conifers Pathogens: Pythium spp., Phytophthora spp., Rhizoctonia solani, Fusarium spp., Cylindrocarpon spp. For more information see: UW Garden Facts XHT1070
Conifer Rhizosphaera Needle Rhizosphaera Needle Cast Hosts: Colorado blue spruce, other spruces, many other conifers Pathogen: Rhizosphaera kalkhoffii For more information see: UW Garden Facts XHT1006; UW-Extension Bulletin A2640
Conifer - Cytospora Canker Cytospora Canker Host: Colorado blue spruce, other spruces Pathogen: Leucocytospora kunzei For more information see: UW Garden Facts XHT1003; UW-Extension Bulletin A2639
Conifer - Spruce Needle Drop Spruce Needle Drop Hosts: Spruces Pathogen: Unknown (thought possibly to be Setomelannoma holmii)
Conifer - Cedar Apple Rust “Cedar-Apple” Rust Hosts: Junipers, apple, crabapple, hawthorn, quince Pathogen: Gymnosporangium spp. For more information see: UW Garden Facts XHT1009a/b; UW-Extension Bulletin A2598
Phomopsis Tip Blight Phomopsis Tip Blight Host: Junipers Pathogen: Phomopsis juniperovora For more information see: UW Garden Facts XHT1099
Conifer - Diplodia Tip Blight Diplodia Tip Blight Hosts: Pines (Austrian, red, jack, Scots, mugo), many other conifers Pathogen: Diplodia pinea For more information see: UW Garden Facts XHT1010; UW-Extension Bulletin A3643
Conifer - Dothistroma Needle_ Dothistroma Needle Blight Hosts: Pines (Austrian, red, Scots, mugo, ponderosa, and others) Pathogen: Dothistroma pini For more information see: UW Garden Facts XHT1078; UW-Extension Bulletin A2620
Conifer - Drought Stress Drought Stress Hosts: All conifers Cause: Insufficient water
Conifer - Winter Injury Winter Injury Hosts: All conifers, particularly yews and junipers Cause: Dehydration over the winter
Conifer - Herbicide Damage Herbicide Damage Hosts: All conifers Cause: Exposure to a growth regulator herbicide such as 2,4-D or dicamba For more information see: UW Garden Facts XHT1004; UW-Extension Bulletin A3286

For more information on conifer diseases: See University of Wisconsin Garden Facts XHT1003, XHT1004, XHT1006, XHT1009a, XHT1009b, XHT1010, XHT1070, XHT1078, XHT1099, XHT1118 or XHT1119, UW-Extension Bulletins A2598, A2620, A2639, A2640, A3286, or A3643, or contact your county Extension agent.

This Fact Sheet is also available in PDF format:

© 2004 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).

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 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.