Practices to Prevent Pathogen Transmission During Tomato Grafting Operations

Transcription

1 Practices to Prevent Pathogen Transmission During Tomato Grafting Operations Sally A. Miller, Kai-Shu Ling, Fulya Baysal-Gurel, Rugong Li, Donna Henderson 8 November 2012 Grafting Mini-Symposium Orlando

2 Greenhouse Tomato Production Flow Seed Crop Work Propagation Germination Seedling production Grafting Topping Transplanting Training Dropping Staking De-leafing Pruning Harvest

3 Grafting Tomatoes and Pathogen Transmission Rootstock and scion = double chance of pathogen introduction Contaminated hands, tools, clothing spread pathogens during grafting and topping Ebb and flow irrigation may spread pathogens

4 Mechanically Transmitted Pathogens High risk to crop health May also be seedborne Bacterial canker Most risky pathogens Clavibacter michiganensis subsp. michiganensis Pepino mosaic virus (PepMV) Viroids Botrytis PepMV Photo Kai-Shu Ling, USDA-ARS Botrytis Photo Fulya Baysal-Gurel, Viroid Photo Kai-Shu Ling, USDA-ARS

5 A Molecular Tool to Study the Biology of Cmm Transmission in Tomato Marked strains to visualize bacteria Cannot interfere with virulence Must be stable Should be active in live cells only Lux genes bioluminescence ATP-dependent actively metabolizing cells emit light Amount of photons emitted correlated with number of living cells Xu et al Appl. Env. Microbiol 76:

6 Cmm Quickly Colonizes Seedlings 1 day 2 day 3 day 4 day 5 day Real-time in vivo images of a tomato seed inoculated with BL Cmm6, taken 1-5 days after seed placed on water agar Rainbow scale represents approximate photon counts (p/s/cm2)

7 Post-Grafting Environment High relative humidity (80-90%), low light (50 % of normal maximum) for the first week Medium relative humidity (50-60%), moderate light (70% of normal maximum) for the second week Conditions typical for tomato seedling acclimation until transplanting

8 Effect of Relative Humidity on Internal Colonization by Cmm 5 DPI 10 DPI 83% RH 45% RH 83% RH 45% RH Three-week old seedlings clip-inoculated with bioluminescent Cmm. Images taken every 5 days post inoculation (DPI). 15 DPI 20 DPI Xu et al Phytopathology 102:

9 Effect of Relative Humidity on Root Colonization by Cmm Control 83% RH 45% RH 20 DPI

10 Can Moisture Management Help Control Bacterial Canker? High moisture during propagation is designed to Enhance germination Encourage seedling growth Heal graft unions quickly Research is needed to Reconcile optimal horticultural conditions with need to minimize bacterial growth and colonization Determine effects of this environment on virus, viroid and fungal transmission

11 Managing by Sanitation An established cultural practice Reduce or eliminate inoculum How effective are common disinfectants in killing mechanically transmitted pathogens during grafting and crop work?

12 Requirements for Sanitizers Very short contact time Broadly effective against viruses, viroids, bacteria and fungi Not dangerous to workers Not corrosive to infrastructure or phytotoxic to plants Economical

13 Product Active Ingredient Rate Clorox 5.25% Sodium hypochlorite 10% KleenGrow Didecyl dimethyl anmmonium chloride 7.5% 4 ml/l Virkon S 20.4% potassium peroxymonosulfate and 1.5% sodium 0.5, 1.0, 2.0% chloride Greenhouse Guardian Trichloromelamine 8 oz/55 gal Green-Shield 1o% n-alkyldimethyl benyl ammonium chloride and 10% n-alkyl dimethyl ethylbenzyl ammonium chloride Non-fat Dry Milk 1 tsp/qt 20% wt:vol Vortexx Hydrogen peroxide6.9%; Peroxyacetic acid 0.94%; 1 oz/4 gal Octanoic Acid 3.3% Octave Hydrogen peroxide 7.52%; peroxyoctanoic acid.94%; 1-2 oz/2 gal Octanoic acid 2.72% Bioside Peroxyacetic acid 15%; hydrogen peroxide 22% 1 oz/10 gal SaniDate Hydrogen peroxide 23%; peroxyacetic acid 5.3% 0.5 oz/gal StorOx 27% hydrogen dioxide 1.25 oz/gal LYSOL.1% alkyl dimethyl ammonium saccharinate undiluted DES-O-Germ Poly hexamethylenebuguanideand benzalkonium chloride ml/100 L Menno Florades 9% benzoic acid 3% Menno- Ter forte Didecyl dimethyl ammonium chloride

14 Methods for Cmm and Botrytis in vitro experiments

15 Number of replicates positive for growth Disinfectant Cmm Botrytis 0 sec 30 sec 1 min 0 sec 30 sec 1 min KleenGrow Green-Shield BioSide Des-O-Germ Menno Florades Menno Terforte Clorox (10%) Vortexx Lysol Storox + +++/ Octave Virkon-S (0.5%) Virkon-S (1 2%) TSP Non-fat dry milk

16 Method for PepMV and SqMV in vivo experiments

17 Infection of Tomato Plants with PepMV after Sanitation 100% 90% 80% 70% % Infection 60% 50% 40% 30% 20% 0 sec 30 sec 60 sec 10% 0%

18 Infection of Zucchini Plants with SqMV after Sanitation % zucchini plants infected

19 Disinfectant Cmm Botrytis PepMV SqMV 1 sec 1 min 1 sec 1 min KleenGrow - - Green-Shield - BioSide - Des-O-Germ - Menno Florades ( ) - Menno Terforte ( ) Clorox (10%) - - Vortexx - - Lysol - - Storox - - ( ) - Octave - - ( ) Virkon-S (1-2%) ( ) TSP ( ) ( ) Non-fat Dry Milk ( ) -

20 Integrated Disease Management Early intervention is critical Seed Prevention Testing Treatment Propagation Environment Sanitation Bactericidal treatments? Testing? Good Seed and Production Practices (GSPP) Production GH sanitation, sanitation, sanitation

21 Acknowledgments OSU Plant Pathology Fulya Baysal-Gurel Xiulan Xu USDA ARS Kai-Shu Ling Rugang Li Monsanto Samantha Thomas Chet Kurowski Donna Henderson USDA NIFA Specialty Crops Research Initiative The Ohio State University - OARDC