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How to Manage Pests

UC Pest Management Guidelines

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Jacket rot on young apricot fruit.

Apricot

Jacket Rot

Pathogens: Botrytis cinerea, Sclerotinia sclerotiorum, Monilinia laxa, and Monilinia fructicola

(Reviewed 11/07, updated 11/07)

In this Guideline:

SYMPTOMS

Jacket rot occurs during the jacket stage when remnants of the flower parts are still attached to the fruit. The disease causes a brown discoloration on the fruit under the jacket. The young fruit withers and falls off the tree within a few weeks.

COMMENTS ON THE DISEASE

Development of jacket rot is favored by wet weather during the bloom and jacket stage.

MANAGEMENT

One fungicide application at full bloom is generally effective. Fungicides applied during the jacket stage are generally ineffective. Treat at full bloom or shortly thereafter but before petal fall. The final bloom spray for blossom brown rot often provides jacket rot control if the appropriate fungicides (Rovral/oil, Topsin M, Pristine, Vanguard) are chosen.

Common name Amount/Acre 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. Also consider the general properties of the fungicide as well as information relating to environmental impact.
 
Caution: Never apply sulfur to apricot trees or captan to apricot fruit.
 
A. IPRODIONE
  (Rovral) 4 1–2 pt 24 0
  MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2)
  COMMENTS: Addition of a narrow range oil (superior, supreme) at 1–2% increases the effectiveness of this material. Do not use after petal fall.
 
B. THIOPHANATE METHYL
  (Topsin-M) 70 WP 1.5 lb 12 1
  MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1)
  COMMENTS: Apply thiophanate methyl in combination with another fungicide of different chemistry. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i.
 
C. PYRACLOSTROBIN/BOSCALID
  (Pristine) 10.5–14.5 oz 12 0
  MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7)
  COMMENTS: To reduce the potential for the development of resistance, do not make more than five applications/season of Pristine or other strobilurin or carboxyanilide fungicides.
 
D. CYPRODINIL
  (Vangard) 75WG 5 oz 12 2
  MODE OF ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9)
 
E. PYRIMETHANIL
  (Scala) SC 18 fl oz 12 2
  MODE OF ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9)
 
F. 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/season and avoid making more than 2 consecutive applications with this material.
 
G. DICHLORAN
  (Botran) 75W 1.33–5.33 lb 12 10
  MODE OF ACTION GROUP NAME (NUMBER1): Aromatic hydrocarbon (14)
 
H. CHLOROTHALONIL
  (Echo 720) 3.125–4.125 pt 12 0
  (Bravo Ultrex) 2.8–3.8 lb 12 0
  (Bravo Weather Stik) 3.125–4.125 pt 12 0
  MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M5)
  COMMENTS: May cause an allergic skin reaction in some people. Do not use with or closely following oil sprays. Do not apply after jacket (shuck) split. Do not apply more than 20.5 pt Bravo Weather Stik/acre/season. Do not apply more than 18.8 lb Bravo Ultrex/acre/season.
 
I. CAPTAN 50 WP 5 lb 4 days 0
  MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M4)
  COMMENTS: Do not apply in combination with, immediately before, or closely following oil sprays. Do not apply after 75% petal fall.
 
 
+  Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) 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.
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, 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.

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

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