What are these orange spots on our tree? - Ask Extension
We have a non fruit producing pear tree that has orangish spots on the leaves. The tree has random branches where all the leaves have died. Not sure w...
Knowledgebase
What are these orange spots on our tree? #833300
Asked June 01, 2023, 10:56 PM EDT
We have a non fruit producing pear tree that has orangish spots on the leaves. The tree has random branches where all the leaves have died. Not sure what it is. Any help would be greatly appreciated.
Baltimore County Maryland
Expert Response
Hi-
The orange spots are a symptom of one of the rust diseases that affect pear trees. These diseases require cedar trees as the alternate host to complete their lifecycle. Where rust diseases are a problem, fungicides are applied early in the growing season. Left unchecked, rust diseases can cause dieback and weaken trees. See VA Tech website below.
There can be many causes of shoot or branch dieback in a pear tree. The pattern and timing of the dieback you are seeing suggest that fireblight is a likely cause.
The incidence of this bacterial disease varies depending on weather conditions, apple cultivar, and the presence of the bacterium. We have had quite a few reports this spring.
Prune out the affected plant parts during dry weather. Fireblight can be prevented in early spring by spraying a copper fungicide at the greentip stage of bud development.
Detailed information on fireblight
https://ohioline.osu.edu/factsheet/plpath-fru-22-0
https://extension.umn.edu/plant-diseases/fire-blight
https://extension.unh.edu/resource/fire-blight-fact-sheet
See the pear pest section and spray guide in this VA Tech pub:
https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/456/456-018/ENTO-523C.pdf
Jon
The orange spots are a symptom of one of the rust diseases that affect pear trees. These diseases require cedar trees as the alternate host to complete their lifecycle. Where rust diseases are a problem, fungicides are applied early in the growing season. Left unchecked, rust diseases can cause dieback and weaken trees. See VA Tech website below.
There can be many causes of shoot or branch dieback in a pear tree. The pattern and timing of the dieback you are seeing suggest that fireblight is a likely cause.
The incidence of this bacterial disease varies depending on weather conditions, apple cultivar, and the presence of the bacterium. We have had quite a few reports this spring.
Prune out the affected plant parts during dry weather. Fireblight can be prevented in early spring by spraying a copper fungicide at the greentip stage of bud development.
Detailed information on fireblight
https://ohioline.osu.edu/factsheet/plpath-fru-22-0
https://extension.umn.edu/plant-diseases/fire-blight
https://extension.unh.edu/resource/fire-blight-fact-sheet
See the pear pest section and spray guide in this VA Tech pub:
https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/456/456-018/ENTO-523C.pdf
Jon
