|Authors: ||S.A. Miller, M.L. Lewis Ivey, F. Baysal-Gurel , Xiulan Xu |
|Keywords: ||bacterial canker of tomato, grey mold, Delphi, HACCP, systems approach, integrated pest management|
Tomatoes are produced under diverse cropping systems that vary from small market gardens to multi-acre high-tech greenhouses.
The incidence and severity of tomato diseases varies by production system, and some diseases that result in serious losses in open field systems may be absent in greenhouse-produced tomatoes, and vice versa.
We are developing a modified Hazard Analysis of Critical Control Points (HACCP) system to manage high-risk diseases in tomato production greenhouses.
The approach involves a thorough analysis of risk factors, followed by identification and confirmation of critical points for pathogen entry and dissemination, and identification of preventative best management practices.
Using the Delphi process, based on a ≥70% consensus level from a panel of experts, we identified major hazards (including bacterial canker, caused by Clavibacter michiganensis subsp. michiganensis (Cmm) and Botrytis grey mold (B. cinerea), and critical points of entry and dissemination of phytopathogens in tomato propagation and production greenhouses.
These include seed, propagation benches, irrigation water, re-used growing medium, non-pollinating insects, tools, equipment, crop debris or culls, and fruit washing and cold storage environments.
Sampling strategies were designed and implemented to determine the relevance of each of the identified sources within the production system, and robust diagnostic assays that include target concentration or trapping followed by culturing, serological assays and PCR. Small, medium and large greenhouses in Ohio, Florida, North Carolina and Canada were identified in order to test potential hazards three times during the growing season.
In initial studies, Cmm was detected in harvest and plant debris bins and irrigation water. Botrytis was detected in debris bins, pruning and harvest gloves, ladders used among rows of tomatoes, floors, tomato debris and weeds found inside the greenhouse. Botrytis spores were also detected in several locations by air sampling.
Information generated in this study will be used to develop best management practices for greenhouse tomato growers at all production scales.
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