Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were
conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total
of 476 and 129 produce samples were collected from 32 organic and 8 conventionalfarms, respectively. The samples included
tomatoes, leafy greens, lettuce, green peppers, cabbage, cucumbers, broccoli, strawberries, apples, and seven other types of
produce. The numbers of fruits and vegetables was in uenced by their availability at participating farms and varied from 11
strawberry samples to 108 tomato samples. Among the organic farms, eight were certi ed by accredited agencies and the rest
reported the use of organic practices. All organic farms used aged or composted animal manure as fertilizer. The average
coliform counts in both organic and conventional produce were 2.9 log most probable number per g. The percentages of E.
coli–positive samples in conventional and organic produce were 1.6 and 9.7%, respectively. However, the E. coli prevalence
in certi ed organic produce was 4.3%, a level not statistically different from that in conventional samples. Organic lettuce
had the largest prevalence of E. coli (22.4%) compared with other produce types. Organic samples from farms that used
manure or compost aged less than 12 months had a prevalence of E. coli 19 times greater than that of farms that used older
materials. Serotype O157:H7 was not detected in any produce samples, but Salmonella was isolated from one organic lettuce
and one organic green pepper. These results provide the rst microbiological assessment of organic fruits and vegetables at
the farm level.