2008 Florida Citrus Pest Management Guide: Preharvest Control of Postharvest Decays
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2008 Florida Citrus Pest Management Guide: Preharvest Control of Postharvest Decays

   

2008 Florida Citrus Pest Management Guide: Preharvest Control of Postharvest Decays1

M.A. Ritenour and L.W. Timmer2

Anthracnose, caused by Colletotrichum gloeosporioides, and stem-end rot, caused by Lasiodiplodia theobromae (Diplodia) or Diaporthe citri (Phomopsis) are postharvest decays that result from latent infections which occur while fruit is still in the grove. Green mold, caused by Penicillium digitatum, frequently occurs following minor injuries to fruit during harvesting and transport. Control of these diseases with postharvest fungicides applied on the packinghouse line becomes less effective as the time between harvest and fungicide treatment exceeds 24 hours. An application of fungicide up to 2 weeks prior to harvest will protect fruit from these diseases during the degreening process or during delays following harvest. The alternative to preharvest treatment is to drench boxes of fruit with imazalil or thiabendazole immediately after harvest.

Recommended Chemical Controls

READ THE LABEL.

See Table 1.

Rates for pesticides are given as the maximum amount required to treat mature citrus trees unless otherwise noted. To treat smaller trees with commercial application equipment including handguns, mix the per acre rate for mature trees in 250 gallons of water. Calibrate and arrange nozzles to deliver thorough distribution and treat as many acres as this volume of spray allows.

Tables

Table 1. Recommended Chemical Controls for Preharvest Fungicide

Pesticide

Mature Trees

Rate/Acre1

Timing
Topsin M WSB2

2 lb3

Apply 2 to 14 days prior to harvest.
1Lower rates can be used on smaller trees. Do not use less than minimum label rate.
2Sec. 18 emergency registration effective until March 2, 2008.
3May result in fruit residues that exceed European maximum residue limits (MRLs). EU MRLs for Topsin are 0.1 ppm compared to 0.5 ppm in the U.S.

Footnotes

1. This document is PP-48, one of a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date printed: December 1995. Date revised: November 2007. This publication is included in SP-43, 2008 Florida Citrus Pest Management Guide. A copy of this publication may be found at http://edis.ifas.ufl.edu/CG008. Please visit the EDIS Web site at http://edis.ifas.ufl.edu. For a copy of this handbook, request information on its purchase at your county extension office.

2. M.A. Ritenour, associate professor, Horticultural Sciences Department, Indian River REC, Ft. Pierce, Florida; and L.W. Timmer, professor emeritus, Plant Pathology Department, Citrus REC, Lake Alfred, Florida; Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. It is not a guarantee or warranty of the products named, and does not signify that they are approved to the exclusion of others of suitable composition.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.


Copyright Information

This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.