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How to Manage Pests
UC Pest Management Guidelines
Plum
Ripe Fruit Rot
Pathogens: mostly Monilinia fructicola and Rhizopus stolonifer
(Reviewed 5/06,
updated 5/06)
In this Guideline:
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SYMPTOMS
Fruit in storage infected with Monilinia fructicola may develop
visible decay within 24 hours at 72°F, and will produce spores in
30 hours. Decaying tissue changes from light brown to gray to black. Rotted tissue is firm and difficult to distinguish from healthy tissue.
Rhizopus stolonifer causes fruit to turn mushy and leaky in storage containers. The disease spreads rapidly from fruit to fruit. Infected tissue can be readily distinguished from healthy tissue.
COMMENTS ON THE DISEASE
Monilinia is the most common fruit decay organism. Fruit that
has been injured and infected before storage provides the inoculum for the
spread of Monilinia. Rhizopus produces
many spores at low humidity, but in fruit packages, where humidity is high,
spores are scarce and mycelia abundant.
MANAGEMENT
Fungicides are preventive, not eradicative; they must be applied to
uninjured fruit before infections occur. Injured fruit cannot be protected from
rot caused by Monilinia or Botrytis with the use
of preharvest sprays. After harvest, Rhizopus can be
controlled by storing the crop at temperatures below 40°F. 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.
Take a fruit sample at
harvest to assess the effectiveness of current year's IPM program and to
determine needs for next year's program. See FRUIT EVALUATION AT HARVEST and record your 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 quality. |
| |
| PREHARVEST |
| A. |
PROPICONAZOLE |
| |
(Orbit) 3.6 EC |
4 fl oz/acre |
0 |
| |
(Bumper) 41.8 EC |
4 fl oz/acre |
0 |
| |
MODE
OF ACTION: A DMI (Group 3)1 triazole fungicide.
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COMMENTS:
Most effective when applied before a rainfall and allowed to dry. Do not apply to "Stanley" type plums. Maximum of 2 preharvest sprays. |
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| B. |
PYRIMETHANIL |
| |
(Scala) SC |
18 fl oz |
2 |
| |
MODE
OF ACTION: An AP (Group 9)1 fungicide.
|
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COMMENTS:
Do not apply more than 2 applications of Group 9 fungicides within 30 days of harvest. |
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| C. |
CYPRODINIL |
| |
(Vangard) WG |
10 oz |
2 |
| |
MODE
OF ACTION: An AP (Group 9)1 fungicide.
|
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COMMENTS:
High summer temperatures and relative humidity reduces efficacy. Apply a
maximum of 2 applications during preharvest. Do not apply more than 20 oz/acre/year. |
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| D. |
PYRACLOSTROBIN/BOSCALID |
| |
(Pristine) |
10.5–14.5 oz/acre |
0 |
| |
MODE
OF ACTION: A Qol (Group 11)1 and carboxamide (Group 7)1
fungicide.
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| E. |
MYCLOBUTANIL |
|
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(Rally) 40W |
2.5–6 oz |
0 |
| |
MODE
OF ACTION: A DMI (Group 3)1 triazole fungicide.
|
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COMMENTS: Do not apply more than 2.75 lb/acre/season. |
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| POSTHARVEST |
| A. |
FLUDIOXONIL |
| |
(Scholar) 50WP |
8 oz/100 gal water |
|
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MODE
OF ACTION: A PP (Group 12)1 fungicide.
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COMMENTS: Treats 200,000 lb fruit using a spray-application system. |
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| B. |
THIOPHANATE METHYL
|
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(Topsin-M) 70W |
8 oz/100 gal water |
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MODE
OF ACTION: A MBC (Group 1)1 thiophanate fungicide.
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COMMENT:
Sporadic control may occur if fruit treated is infected with spores of
benzimidazole-resistant strains of Monilinia spp. If resistance has occurred in your orchard, do not use this fungicide. |
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More information on plum fungicides
![[Precautions]](/IMAGES/btn-precautions_bul.gif)
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
Diseases
W. D. Gubler, Plant Pathology, UC Davis
J. E. Adaskaveg, Plant Pathology, UC Riverside
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to the diseases section:
B. L. Teviotdale, Kearney Agricultural Center, Parlier
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