Spinach is a fast-maturing, cool-season vegetable crop. In California, most conventional and organic spinach fields are irrigated by sprinkler irrigation. However, sprinkler irrigation could contribute to the speed and severity of downy mildew epidemics, as the most important disease in spinach, within a field when other conditions such as temperature are favorable.

Although fungicides are available for the control of downy mildew in conventional production systems, products with similar efficacy are not available for organic spinach. Adapting drip irrigation for high-density spinach plantings may be a possible solution to reduce yield losses from downy mildew and enhance resource-use efficiency in organic spinach...