Survival and Transfer of Escherichia coli from Plastic Mulch to Field-Grown Tomatoes and Bell Peppers with Ground Contact

Foodborne illness from preharvest contamination is of concern in vegetables often eaten raw, such as tomatoes and bell peppers. The objective of this thesis was to use surrogate E. coli TVS 353 GFP to understand bacterial survival over time on different types of plastic mulch (black or white; reused or new) during tomato and pepper harvest maturity in different seasons (summer and fall) and to obtain transfer rates from plastic mulch to fruit with ground contact (drooping or dropped fruit). In both summer and fall seasons, inoculated bacterial populations rapidly decreased in the field environment, and dry inoculum populations transferred 0.01% to 2.86% from plastic mulch to fruit. Overall, environmental factors unique to the field environment including temperature, relative humidity, UV radiation, and surface temperature of mulch resulted in rapid bacterial reductions as well as low percent transfer from mulch to fruit.