Current nd New Tools for Controlling Posthrvest Decy of Fresh Citrus Mrk Ritenour & Jiqi Yn Indin River Reserch nd Eduction Center, Fort Pierce
Control Options Prehrvest - No relile replcement yet for Benlte or Topsin However, copper, Aliette, nd phosphorous cid products to reduce Brown rot Posthrvest control mesures Good snittion prctices Creful hndling Good snittion prctices Use of fungicide Must e effective ginst ltent orgnisms such s Diplodi nd Anthrcnose Diplodi stem-end rot
Thiendzole (TBZ) Controls stem-end rot nd green mold Some effectiveness ginst nthrcnose Does not control sour rot or lck rot Recommended concentrtions: 1000 ppm (0.1%) s wter suspension 2000 ppm (0.2%) in wter-sed wx Not very solule in wter Constnt gittion required Include snitizer (e.g., chlorine) with recirculted solutions
Imzlil Especilly effective ginst green mold. Diplodi nd Phomopsis - generlly less effective thn TBZ. Some ctivity ginst lck rot. Ineffective ginst sour rot nd rown rot. Recommended concentrtions 1000 ppm (0.1%) s wter suspension 2000 ppm (0.2%) in wter-sed wx Not comptile with chlorine.
SOPP Sodium o-phenylphente, lso clled 2 Phenylphenol O-phenylphenol (OPP) Effective ginst green mold & sour rot Little to no control of Diplodi or Phomopsis stem-end rot, or lck rot Recommended concentrtion: 2% queous solution, ph t 11.5 12.0 is the most effective tretment Some include 0.2% sodium hydroxide for ph control, nd 1% hexmine to minimize phytotoxicity
Fludioxonil Effective ginst green mold nd Diplodi stem-end rot Much less green mold sporultion control compred to imzlil Comined with zoxystroin (Grdute A+) = Good sporultion control Comptile with chlorine
Phosphites Ruy Red grpefruit Inoculted for Brown rot Nturl infections of diplodi Tretment Brown Rot (%) Diplodi SER (%) Control 45.0 23.8 TBZ 40.6 6.9 Potssium Phosphite 8.1 c 4.4 Potssium Phosphite + TBZ 13.1 c 0.6 75 F 38.5 9.6 120 F 17.9 5.0 Two weeks fter inocultion
Phosphites Murcott' tngerine fruit Inoculted for Brown rot Nturl infections of diplodi Tretment Brown Rot (%) Diplodi SER (%) Control 17.5 11.9 TBZ 15.6 1.9 Potssium Phosphite 3.1 c 4.4 Potssium Phosphite + TBZ 6.3 c 3.2 75 F 14.8 7.5 120 F 6.3 1.7 Two weeks fter inocultion
Essentil oil solution dip on CBS development Effects of thymol nd crvcrol dip on CBS lesion development on symptomtic fruit 2.0 1.5 0.2 mg/ml 0.5 mg/ml 1 mg/ml 2 mg/ml Lesions per fruit 1.0 0.5 0.0 Control Crvcrol Thymol Com (1:1) Tretments Thymol, crvcrol, nd the comintion (1:1) t 2 mg/ml resulted in phytotoxic peel injury, with the most severe dmge cused y thymol which lso cused peel injury t 1 mg/ml
Essentil oil mixed in wx on CBS development Effects of thymol nd crvcrol mixed in wx on lesion development on symptomtic fruit 2.0 1.5 1 mg/ml 2 mg/ml 5 mg/ml Lesions per fruit 1.0 0.5 c c c c c c c c c c 0.0 Control Wx Crvcrol Thymol Com (1:1) TBZ + IMZ Tretments On fruit tht were symptomtic efore tretment, coting with shellc contining 5 mg/ml of thymol, crvcrol, nd the comintion (1:1) reduced the numer of lesions formed on fruit significntly (p<0.05)
Essentil oil mixed in wx on diplodi development 120 Effects of thymol nd crvcrol mixed in wx on Diplodi decy of INOCULATED fruit 12 hrs. prior to wxing A Lesion re (cm 2 ) 90 60 30 Control Wx 0.1% 0.2% 0.5% 1.0% c c c c c c 0 48 72 B Lesion re (cm 2 ) 120 90 60 30 c c c c 0 48 72 Hours fter inocultion
Essentil oil mixed in wx on diplodi SER 120 development A Effects of thymol nd crvcrol mixed in wx on Diplodi decy of INOCULATED fruit, immeditely fter wxing Disese Incidence (%) 90 60 30 Crvcrol C Lesion re (cm 2 ) 120 90 60 30 0 Control Wx 0.1% 0.2% 0.5% 1.0% 0 B Disese Incidence (%) 120 90 60 30 Thymol 12 D 9 6 3 Lesion re (cm 2 ) 0 Control Wx 0.1% 0.2% 0.5% 1.0% Tretments nd concentrtions
Essentil oil mixed in wx on Diplodi development Effects of thymol nd crvcrol mixed in wx on diplodi decy from NATURAL infections 80 Nturl decy (%) 60 40 20 Control Crvcrol * Wx Thymol * 0 0 4 8 8+1 Weeks of storge
Recommended Degreening Conditions Florid Temperture 28 to 29 o C (82 to 85 o F) Ethylene 5 ppm Humidity 90 to 96% Ventiltion (keep elow 0.1% CO 2 ) 1 ir chnge per hour Air Circultion 100 CFM per 900 l. in (CFM = cuic feet per minute)
Temperture Grierson & Newhll, 1953
Potentil Prolems Tempertures too high ove 85F, slows rte of chlorophyll degrdtion, ut increses fruit metolism, decy, nd rekdown Too much wter in the rooms fruit stys wet = slower degreening & incresed decy pressure Ethylene is not very solule in wter
Ventiltion & Cron Dioxide Ventiltion removes wste gsses (e.g., CO 2 nd possily peel oil vpor) 1% CO 2 cn out stop degreening Ventiltion lso results in more uniform temperture throughout the room Result in fster nd more uniform color development within the lod Continuous ventiltion is often etter thn periodiclly opening the room Excessive ventiltion wstes ethylene nd (when used) heting
Potentil Prolems Poor ir circultion = uneven temperture distriution nd locl uildups of CO 2 in the room Both = uneven color development
Wht Inhiits Color Development? Wrm wether prticulrly wrm nights Regreening in the Spring Fctors tht promote vigorous growth high rinfll high nutrient levels (esp. N & K) Field oil sprys Peel oil (e.g., from rushing) Some scle insects (e.g., chff & purple scle)
Acknowledgements Megn Dewdney Pmel Roerts Jiuxu Zhng Cuifeng Hu Jin Li
Thnk you! Question?