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How to Manage Pests
UC Pest Management Guidelines
Nectarine
Scab
Pathogen: Cladosporium carpophilum
(Reviewed 6/06,
updated 6/06)
In this Guideline:
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SYMPTOMS
Scab affects foliage, young shoots, and fruit, but damage is the
result of fruit infections. Fruit infections appear as dark lesions on
ripening fruit, most commonly on the upper surface,
and may grow together to form large blotches. Lesions may have green or
yellowish blotches that turn grayish when spores are produced.
Primarily a problem on nectarines in the northern San Joaquin Valley
during wet spring weather. The fungus that causes scab overwinters in lesions
on first-year twigs. Spores are produce in these lesions when humidity exceeds
70% beginning at bloom and lasting several weeks. Spores are spread by air
movement and splashing water and will infect developing fruit, although it may
take several weeks for lesions to appear.
In orchards with a history of scab, applications of a fungicide
within 3 weeks after full bloom to protect developing fruit, and again at 5
weeks if disease was severe the previous year, will reduce fruit infection.
Fungicides applied during bloom for brown rot and at petal fall to control shot
hole will also reduce the spread of scab if appropriate fungicides are chosen.
Take a fruit damage sample at harvest to assess the effectiveness
of the current year's IPM program and to determine the needs of next year's
program (see FRUIT
EVALUATION AT HARVEST) and record
results on a monitoring form .
| Common name |
|
P.H.I.+ |
| (trade name) |
Amount to Use |
(days) |
|
| 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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| A. |
AZOXYSTROBIN |
| |
(Abound) |
12.3–15.4 fl oz/acre |
0 |
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MODE OF ACTION: A Qol (Group 11)1
fungicide.
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COMMENTS: Do not apply more than two
applications before alternating with a fungicide that has a different Group number. |
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| B. |
FENBUCONAZOLE |
| |
(Indar) 75WSP |
2 oz/acre |
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MODE
OF ACTION: A DMI (Group 3)1 triazole fungicide.
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COMMENTS: Do not apply more than 1 lb/acre/season. |
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| C. |
PYRACLOSTROBIN/BOSCALID |
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(Pristine) |
10.5–14.5 oz/acre |
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MODE OF ACTION: A Qol (Group 11)1
and carboxamide (Group 7)1 fungicide.
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COMMENTS: To reduce the potential for
resistance, do not make more than 5 applications of this or other Group 11 or
7 fungicides per season. Do not make more than 2 sequential applications of this product. |
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| D. |
THIOPHANATE METHYL |
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(Topsin-M) 70WP |
8 oz/100 gal water |
1 |
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MODE
OF ACTION: A MBC (Group 1)1 thiophanate fungicide.
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| E. |
CAPTAN 50WP |
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(various products) |
2 lb/100 gal water (dilute spray) |
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MODE OF ACTION: A multi-site contact (Group
M4)1 phthalimide fungicide.
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COMMENTS: Do not apply in combination with, immediately before, or closely following oil sprays. |
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| F. |
ZIRAM 76DF |
2–2.5 lb/100 gal water (dilute spray) |
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MODE OF ACTION: A multi-site contact (Group
M3)1 dithiocarbamate fungicide.
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More information on nectarine fungicides
UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
Diseases
W. D. Gubler, Plant Pathology, UC Davis
J. E. Adaskaveg, Plant Pathology, UC Riverside
Acknowledgment for contributions to the diseases section:
B. L. Teviotdale, Kearney Agricultural Center, Parlier
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