Summary of Awards to Date

Risk assessment of Salmonella preharvest internalization in relation to irrigation water quality standards for melons and other cucurbits.


Jan. 1, 2011 - Jan. 31, 2012

Award Number


Funding Agency

Center for Produce Safety

Amount Awarded



Trevor Suslow, Ph.D.
University of California, Davis


The production of melons, including cantaloupe, honeydew, and watermelon, and other
cucurbits (specialty melons, cucumber, and squash) requires ample quantities of irrigation
water of appropriate microbiological quality to ensure this essential input does not contribute
to food safety risk to consumers. A great deal of uncertainty surrounds the setting of rationale
and practical standards for growers to follow to meet these expectations. In open
enVironments, it is unreasonable to expect that no pathogens of concern will ever be in surface
water used for irrigation at some low level. Internalization of pathogens from soil and transfer
to edible portions of fruits and vegetables has become a concern in recent years. The primary
purpose of this research is to determine, by greenhouse and open field testing, the threshold
level of Salmonella that would be required to represent a risk of fruit contamination by uptake
of pathogen-contaminated irrigation water through the root system and subsequent transfer
through the vine. We anticipate this threshold will be 10,000's times higher than levels of
Salmonella reported in irrigation source water for domestic production of these crops. Food
safety standards for melons and cucurbits will not need to remain preoccupied with the risk of
internalization from roots.