Prevalence and control of pathogenic contamination in some sewage irrigated vegetable, forage and grain crops

Abstract

A total of 344 samples comprising of different vegetables, fodder and grain crops were obtained from a long-term experiment under sewage irrigation. The aerobic bacterial plate counts for vegetables, fodder and grain crops ranged between 2 · 106 and 3.5 · 107, 6 · 106 and 3 · 108, 2 · 105 and 3.8 · 1010, respectively, while the corresponding Faecal coliform ranged between <2 and 9 · 105, 9 · 102 and 2 · 105 and <2, indicating that the pathogenic loads got reduced below permissible level in the produce that was harvested after sun drying in the field itself, whereas the parts coming in direct contact were the most severely contaminated. The health hazards could be markedly lowered with adoption of some of the low cost practices such as repeated washings, exposure of the produce to sunlight and raising the crops on beds. The coliform counts in vegetables were within permissible limits by two washings with water, exposing these to sunlight for about 4 h and removing the two outmost leaves of cabbage. Also, cutting above some height from ground level (0.10 m) in sorghum reduced the pollution load in fodder crops.