Purpose: To document the occurrence of pathogens and fecal indicator organisms on farms that incorporated GAPs versus those that did not. Fifteen farms were selected based on their level of GAPs adherence and compliance [GAPs compliant, n= 8 (GAP A) and GAPs non-compliant, n= 7 (GAP B)].
Methods: Farms enrolled were a mixture of conventional, non-certified organic and certified organic. Each farm was visited 3 times over the growing season. Producers were interviewed with a standard questionnaire and samples were taken from compost, harvesting tools, containers and water samples. Samples were tested for coliforms, Escherichia coli, E. coli O157:H7, and Salmonella.
Results: All enrolled farms grew leafy greens. The average size was 3.5 acres with a median of 5 workers. No seasonal differences in total coliform counts were observed among all the surveyed farms (p=0.13). Water samples from GAP A farms had lower coliform counts (2.5 coliforms /l) compared to GAP B farms (12.56 coliforms /l). GAP B farms consistently had compost containing average coliform counts greater than 10,000 CFU/g compared to GAP A farms (R.R 1.4 95% CI 1.12-1.92, P < 0.01). Six (42%) of 14 farms had E. coli isolated from compost samples. Two had levels of E. coli with more than 100 CFU/g. There was no difference in recovery of E. coli between GAP B (26.1%) and GAP A farms (22.2%). Salmonellawas not recovered from participating farms.
Significance: We observed differences in coliform counts from compost piles between farms that incorporated GAPs vs. those that did not. Additional work is needed to evaluate the effect of GAP incorporation on product safety.