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How to Manage Pests
UC Pest Management Guidelines
Cherry
Bacterial Canker
Pathogen: Pseudomonas syringae
(Reviewed 4/06,
updated 4/06)
In this Guideline:
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Symptoms are most obvious in spring, and include limb die back with
rough cankers and amber colored gum. There may also be leaf spot and blast of young
flowers and shoots.
The sour sap phase of bacterial canker may not show gum and cankers, but the
inner bark is brown, fermented, and sour smelling. Flecks and
pockets of bacterial invasion in bark occur outside canker margins. Frequently,
trees sucker from near ground level; cankers do not extend below ground.
Pseudomonas syringae survives on plant surfaces, is spread by splashing rain, and is
favored by high moisture and low temperatures in spring. The disease is worse
in low or sandy spots in the orchard. Vigorous trees are less susceptible to
bacterial canker, while young trees, 2 to 8 years old, are most affected. The
disease rarely occurs in first year of planting, and is uncommon in nurseries.
Delayed pruning may help. Of the rootstocks commonly used for
cherries in California, Mahaleb is the most tolerant of bacterial canker, Colt
is moderately susceptible, and Mazzard is susceptible. Copper sprays applied at
the beginning and end of leaf fall have given variable control.
Treatment Decisions
In light,
sandy soils and in some heavy soils, control has been achieved with preplant
fumigation for nematodes. Nematodes stress trees, which predisposes them to
bacterial canker. The benefits of preplant soil fumigation for control of
bacterial canker usually last only a few years; in some areas only limited
improvements in disease control occur following soil fumigation.
Following planting, if bacterial canker occurs in an orchard,
treat all trees with fenamiphos in that area of the orchard on a yearly basis
until the trees are 8 years old.
| Common name |
Amount/Acre |
P.H.I.+ |
| (trade name) |
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(days) |
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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
impact.
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| PREPLANT |
| A. |
METHYL BROMIDE* |
300–600 lb |
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COMMENTS: Use allowed under a Critical Use
Exemption only. Use higher rates for fine-textured soils. Fumigants such as
methyl bromide are a prime source of volatile organic compounds (VOCs), which
are a major air quality issue. Fumigate only as a last resort when other management strategies have not been successful or are not available. |
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| POSTPLANT |
| A. |
FENAMIPHOS* |
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(Nemacur 3) |
0.5–1.5 gal |
45 |
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COMMENTS: Apply in mid-Oct. through low-volume irrigation (drip line or minisprinkler). |
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UC IPM Pest Management Guidelines: Cherry
UC ANR Publication 3440
Diseases
J. E. Adaskaveg, Plant Pathology, UC Riverside
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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