How to Manage Pests
UC Pest Management Guidelines
Apple
European Canker
Pathogen: Nectria galligena
(Reviewed 8/06,
updated 8/06)
In this Guideline:
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In fall or spring European canker causes reddish brown lesions to
appear on small branches just below leaf scars. These elongate into cankers
with concentric ridges and may cause dieback of shoots in spring. Calyx rot of
fruits can occur in years when rain precedes harvest. Pruning wound infections
are seen occasionally (especially on the Delicious cultivar). On superficial
examination, such infections may be confused with fire blight.
This fungus survives in old bark cankers and produces spores that
enter fresh leaf scars during fall rains. The Delicious variety is most
susceptible, followed by Gravenstein and Rome Beauty. This disease is worse in
the Sebastopol area of Sonoma County in years with prolonged fall rains.
European canker is managed primarily by pruning and protectant
fungicides. Cankers should be pruned out of trees as they ultimately kill
branches and also serve as sources of inoculum. Prune and burn diseased wood
early in summer. At this time symptoms are obvious and spread of the fungus is
not likely. Because infection occurs through leaf scars and leaves fall over a
long period, two treatments are necessary each fall to protect new leaf scars.
Organically Acceptable Methods
Treatments with Bordeaux or approved fixed
copper materials are organically acceptable.
Treatment Decisions
If European canker is damaging your
orchard, apply a freshly prepared Bordeaux mixture of 10:10:100 or a fixed
copper material at label rates during early leaf fall, before rains begin. Where
the disease is serious, make a second application when three-fourths of the
leaves have fallen.
| Common name |
Amount to Use |
| (trade name) |
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| The following materials are listed in order of
usefulness in an IPM program, taking into account efficacy. When choosing a
pesticide, also consider information relating to environmental quality.
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| A. |
BORDEAUXMIXTURE# |
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10:10:100 |
Label rates |
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MODE
OF ACTION: A multi-site contact (Group M1)1 inorganic fungicide.
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| B. |
FIXED COPPER# |
Label rates |
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MODE
OF ACTION: A multi-site contact (Group M1)1 inorganic fungicide.
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COMMENTS: Not all copper compounds are approved for use in organic production; be sure to check individual products. |
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UC IPM Pest Management Guidelines: Apple
UC ANR Publication 3432
Diseases
W. D. Gubler, Plant Pathology, UC Davis
Acknowledgment for contributions to the diseases section:
B. L. Teviotdale, Kearney Agricultural Center, Parlier
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