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How to Manage Pests
UC Pest Management Guidelines
Nectarine
Ripe Fruit Rot
Pathogens: Monilinia fructicola, Botrytis cinerea, Rhizopus
spp.
(Reviewed 6/10,
updated 6/10)
In this Guideline:
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Ripe fruit rot caused by Monilinia or Botrytis
results in firm, circular spots that spread rapidly over fruit. Monilinia causes dark brown lesions on
fruit that eventually turn black from the development of pseudosclerotia
(fungal tissue), whereas Botrytis
causes light tan to grayish lesions with gray spores. Spore masses may grow on
the rotted areas. Fruit becomes more susceptible as it ripens. Botrytis-diseased fruit usually do not
remain on the tree until next season, but they are present as inoculum sources
for the current season's crop. When Monilinia-diseased
fruit remain on the tree, they are known as mummies.
Rhizopus rot is a postharvest storage
problem. The decaying fruit tissue is watery and soft; the fungus is identified
by masses of white mycelium with tiny black sporangia that form most abundantly
on fruit near the edge of containers.
Monilinia and Botrytis can infect
uninjured ripening fruit and cause green fruit rot and incipient infections of
young fruit. Wetness, either rain or dew, and injury or fruit cracking
increases preharvest infection and subsequent rot. Rhizopus spp. invades only ripe fruit that have been injured and
the decay is a postharvest concern only.
Fruit rot is managed by controlling blossom and twig
blight in spring, removing blighted twigs when possible, using appropriate
levels of nitrogen fertilizer and water, removing or turning under thinned
fruit, controlling fruit-feeding insects such as peach twig borer and oriental
fruit moth, and making preharvest treatments when necessary. Early maturing
cultivars typically have little trouble with ripe fruit rot.
Take fruit samples every other week after
color break (see PREHARVEST FRUIT SAMPLES) to
detect any developing problems in the orchard and 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. Record results for
harvest sample.
Organically
Acceptable Methods
Treatments of sulfur dust
are acceptable for use in an organically certified crop.
Chemical
Control
Fungicides are preventive,
not eradicative; they must be applied to uninjured fruit before infections
occur. Injured fruit cannot be protected from Monilinia or Botrytis rot
by preharvest sprays. Preharvest sprays for Monilinia
should be applied as needed during the last 4 weeks before harvest. Where Rhizopus fruit rot is a problem, treat
10 days to 1 day before harvest. After harvest, Rhizopus can be controlled by storing the crop at temperatures
below 40°F.
| Common name |
Amount to Use |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
|
(hours) |
(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. Not all registered pesticides are listed.
Always read label of product being used.
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| A. |
TEBUCONAZOLE/TRIFLOXYSTROBIN |
| |
(Adament 50 WG) |
4–8 oz/acre |
5 days |
1 |
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MODE OF ACTION GROUP
NAME (NUMBER1): Demethylation inhibitor (3) and Quinone outside inhibitor (11) |
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| B. |
PROPICONAZOLE |
| |
(Bumper, Tilt) |
4 oz/acre |
Tilt: 12
Bumper: 24
|
0 |
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MODE
OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
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COMMENTS: Maximum of 2 preharvest sprays. |
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| C. |
TEBUCONAZOLE |
| |
(Elite, etc. 45WP) |
4–8 oz/acre |
12 |
0 |
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MODE
OF ACTIONo GROUP NAME (NUMBER1): Demethylation inhibitor (3)
|
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COMMENTS: Do not apply more than 3 lb/acre/season. |
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| D. |
FENBUCONAZOLE |
| |
(Indar 75WSP) |
2 oz/acre |
12 |
0 |
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MODE
OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
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COMMENTS: Do not apply more than 1 lb/acre/season. |
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| E. |
THIOPHANATE METHYL |
| |
(Topsin-M, etc. 70W) |
8 oz/100 gal water |
12 |
1 |
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MODE
OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1)
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COMMENTS: One
application only per season and always apply with a companion fungicide with
a different mode of action group number. Strains of brown rot resistant to
thiophanate methyl have been found in California. If resistance has occurred in your orchard, do not use this fungicide. |
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| F. |
PYRACLOSTROBIN/BOSCALID |
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(Pristine) |
10.5–14.5 oz/acre |
12 |
0 |
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MODE OF ACTION GROUP
NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7)
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| G. |
FENHEXAMID |
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(Elevate 50 WDG) |
1–1.5 lb/acre |
12 |
0 |
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MODE OF ACTION GROUP
NAME (NUMBER1): Hydroxyanilide (17)
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COMMENTS: Avoid making more than 2 consecutive applications of this material. |
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| H. |
MYCLOBUTANIL |
| |
(Rally 40W) |
2.5–6 oz/acre |
24 |
0 |
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MODE
OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
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| I. |
CAPTAN 50WP |
2 lb/100 gal water |
24 |
0 |
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MODE OF ACTION GROUP
NAME (NUMBER1): Multi-site contact (M4)
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COMMENTS: Do not apply in combination with, immediately before, or closely following oil sprays. |
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| J. |
SULFUR DUST# |
50 lb/acre |
see label |
see label |
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MODE OF ACTION GROUP
NAME (NUMBER1): Multi-site contact (M2)
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COMMENTS: Do not apply within 3 weeks of an oil application. |
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| POSTHARVEST |
| A. |
FLUDIOXONIL |
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(Scholar 50WP) |
8–16 oz/100 gal water |
NA |
NA |
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MODE OF ACTION GROUP
NAME (NUMBER1): Phenylpyrrole (12)
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COMMENTS: Treats 200,000 lb fruit using a spray-application system. |
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IMPORTANT LINKS
![[Precautions]](/IMAGES/btn-precautions_bul.gif)
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
Diseases
J. E. Adaskaveg, Plant Pathology, UC Riverside
R. A. Duncan, UC Cooperative Extension Stanislaus County
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Diseases:
B. L. Teviotdale, Kearney Agricultural Center, Parlier
W. D. Gubler, Plant Pathology, UC Davis
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