How to Manage Pests

UC Pest Management Guidelines

Apricot

Ripe Fruit Rot

Pathogens: Monilinia fructicola, Monilinia laxa

(Reviewed 10/14, updated 10/14)

In this Guideline:


SYMPTOMS AND SIGNS

Dark brown, firm, circular spots spread rapidly over fruit, and tan spore masses form in the centers of lesions. Ripening fruit is most susceptible. Diseased fruits (mummies) may remain on the tree until the next season.

COMMENTS ON THE DISEASE

Ripe fruit rot (also called brown rot of fruit) is not as important as blossom blight in southern production areas of California. In northern production areas, ripe fruit rot can be devastating. Warm rains near harvest can lead to fruit rot infection in a few hours. At 67°F, fruit rot symptoms will appear within 48 hours of rain.

MANAGEMENT

Apricots are extremely susceptible to ripe fruit rot. Use IPM practices to decrease fruit susceptibility and reduce the potential for ripe fruit rot.

  • Manage brown rot blossom and twig blight.
  • Avoid excessive nitrogen fertilization.
  • Do not over-irrigate (increases humidity).

The need for preharvest treatment depends upon crop set and environmental conditions during fruit ripening. The threat of rain or heavy dews during the last 2 to 3 weeks before harvest may signal the need for protection.

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 SAMPLING AT HARVEST). Record results (sample formPDF).

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

UPDATED: 10/14
Calculate impact of pesticide on air quality
When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide's properties, efficacy, application timing, and information relating to resistance management, honey bees, and environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.
 
Caution: Never apply sulfur to apricot trees or captan to apricot fruit.
 
PREHARVEST
 
A. PROPICONAZOLE
  (Bumper ES, Tilt) 4 fl oz 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
 
B. FENBUCONAZOLE
  (Indar 2F) 6 fl oz 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
  COMMENTS: Apply a minimum of 50 gal water/acre. A protectant fungicide. Begin applications before infections occur if conditions are conducive to disease development.
 
C. PYRACLOSTROBIN / FLUXAPYRAXAD
  (Merivon) 4–6.7 fl oz 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Succinate dehydrogenase inhibitors (7)
  COMMENTS: To reduce the potential for the development of resistance, do not make more than two consecutive applications or more than four applications or 20.1 fl oz per season of Merivon or other quinone outside inhibitor (11) or succinate dehydrogenase inhibitor (7) fungicides.
 
D. PYRACLOSTROBIN / BOSCALID
  (Pristine) 10.5–14.5 oz 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Succinate dehydrogenase inhibitors (7)
 
E. TEBUCONAZOLE / TRIFLOXYSTROBIN
  (Adament 50WG) 4–8 oz 120 (5 days) 1
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3), Quinone outside inhibitor (11)
  COMMENTS: Use allowed under a Supplemental Label.
 
F. TEBUCONAZOLE
  (Tebucon 45DF, Toledo 45DF) 4–8 oz 120 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
  COMMENTS: Toledo use allowed under a Supplemental Label.
 
G. METCONAZOLE
  (Quash) 3.5–4 oz 12 14
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
 
H. DIFENOCONAZOLE / AZOXYSTROBIN
  (Quadris Top) 12–14 fl oz 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3), Quinone outside inhibitor (11)
  COMMENTS: For ripe fruit rot management on fruit begin applications at full bloom. Do not apply more than twice during preharvest with a minimum of 7 days between treatments.
 
I. DIFENOCONAZOLE / CYPRODINIL
  (Inspire Super) 16–20 fl oz 12 2
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3), Anilinopyrimidine (9)
  COMMENTS: For ripe fruit rot management on fruit begin applications at full bloom. Do not apply more than twice during preharvest with a minimum of 7 days between treatments.
 
J. AZOXYSTROBIN / PROPICONAZOLE
  (Quilt Xcel) Label rates 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11), Demethylation inhibitor (3)
  COMMENTS: For ripe fruit rot management on fruit begin applications at full bloom. Do not apply more than twice during preharvest with a minimum of 7 days between treatments.
 
K. PYRIMETHANIL
  (Scala SC) 18 fl oz 12 2
  MODE-OF-ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9)
  COMMENTS: Efficacy is reduced under conditions of high temperatures (high 90s and above) and high humidity. Resistant populations have been identified in Californian stone fruit orchards. Do not apply more than two consecutive applications or more than four applications per season of pyrimethanil or other anilinopyrimidine Group 9 fungicides.
 
L. THIOPHANATE METHYL
  (Topsin M 70WP) 0.5 lb/100 gal water up to 1.5 lb/acre 48 1
  MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole carbamate (1)
  COMMENTS: Apply only once per year. If thiophanate methyl was used earlier for brown rot or powdery mildew control, do not use it for control of ripe fruit rot. Check with your processor before using this material. Strains of Monilinia fructicola resistant to thiophanate methyl have been found in California apricot orchards. If resistance has occurred in your orchard, do not use this fungicide.
 
M. MYCLOBUTANIL
  (Rally 40WSP) 2.5–6 oz 24 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
  COMMENTS: Do not apply more than 2.75 lb/acre per season.
 
N. FENHEXAMID
  (Elevate 50WDG) 1–1.5 lb 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Hydroxyanilide (17)
  COMMENTS: Do not apply more than 6 lb/acre per season.
 
O. CYPRODINIL
  (Vangard 75WG) 10 oz 12 2
  MODE-OF-ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9)
  COMMENTS: Efficacy is reduced under conditions of high temperatures (high 90s and above) and high humidity. Resistant populations have been identified in California stone fruit orchards. Do not apply more than two consecutive applications or more than four applications per season of cyprodinil or other anilinopyrimidine Group 9 fungicide.
 
P. PENTHIOPYRAD
  (Fontelis) 14–20 fl oz 12 0
  MODE-OF-ACTION GROUP NAME (NUMBER1): Succinate dehydrogenase inhibitors (SDHI) (7)
  COMMENTS: Resistance warning: do not make more than two consecutive applications and no more than 61 fl oz/ acre per year of Fontelis or other SDHI fungicide.
 
POSTHARVEST
 
A. FLUDIOXONIL
  (Scholar) 8–16 oz/100 gal water NA NA
  MODE-OF-ACTION GROUP NAME (NUMBER1): Phenylpyrrole (12)
  COMMENTS: Treats 200,000 lb fruit using a spray-application system. Do not make more than one postharvest application to the fruit.
 
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
NA Not applicable.
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. For fungicides with mode-of-action group numbers 1, 4, 7, 9, 11, or 17, make no more than one application before rotating to a fungicide with a different mode-of-action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action group number.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Apricot
UC ANR Publication 3433

Diseases

J. E. Adaskaveg, Plant Pathology, UC Riverside
W. D. Gubler, Plant Pathology, UC Davis
W. W. Coates, UC Cooperative Extension, San Benito County
J. J. Stapleton, UC IPM Program, Kearney Agricultural Center, Parlier
J. L. Caprile, UC Cooperative Extension, Contra Costa County
B. A. Holtz, UC Cooperative Extension, Madera County
K. M. Kelley Anderson, UC Cooperative Extension, Stanislaus County

Acknowledgment for contributions to Diseases:
B. L. Teviotdale, Kearney Agricultural Center, Parlier

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