Spinach: The Resilient Vegetable
The image of Popeye opening a can of spinach, pouring it into his mouth, and then cleaning up the bad guys still lingers in the imagination of many people of the Baby Boomer generation. I am not sure how many from the X, Y, and millennial generations have seen Popeye cartoons but hopefully the image of spinach as a food that can keep you healthy and strong remains strong, minus the influence of Popeye in popular culture.
The spinach industry has changed over the years to keep pace with the changing preferences of the market.
In California, spinach is produced nearly all year, but the emphasis of the industry has shifted from Popeye’s canned spinach to fresh and frozen products.
This leafy green is produced year-round in California on 26,900 acres. It is a cool-season vegetable that is tolerant of light freezes but for commercial production it is like a snowbird and follows the good weather south in the winter.
For instance, during the winter it is produced in the desert valleys and is harvested November to March. Production then moves back north to the coastal and central valleys which provide production over the remainder of the year.
About half of the production is in Monterey County alone which produced 13,900 acres in 2011. Spinach is now grown as three commodities: washed and bagged; bunched; and frozen. Bagged spinach (also known as clipped spinach because it is mechanically harvested) is produced on the majority of acreage.
Spinach production has changed dramatically in the last 15 years and has adapted to numerous challenges. Nearly all clipped spinach is now grown on high-density 80-inch wide beds. Seeding rates depend on the commodity being grown. Baby and teenage clipped fields are seeded with 2.7 to 4.0 million seeds per acre, whereas bunched and freezer spinach will vary from 1.0 to 2.3 million seeds per acre. Nearly all the production is of varieties with smooth, flat leaves.
Downy mildew is a serious production problem for spinach and there are now 14 races of this disease; seed companies are constantly developing varieties resistant to races of this disease. Resistant varieties are an important way the industry manages downy mildew, in addition to control provided by fungicides.
Water Quality Concerns
Water quality issues are also a serious concern for growers in the coastal production districts and spinach is a particularly vulnerable commodity to water quality concerns. Spinach has several characteristics that put it at risk for leaking nitrate to ground and surface waters. Those characteristics include: 1) it is shallow rooted, 2) the deep-green color of the leaves is a key quality characteristic, and 3) although it takes up only a moderate amount of nitrogen, nearly all of it is taken up in the final two weeks of the production cycle.
As a result, nitrogen application rates can be rather robust, especially in the spring when rain events make it difficult to maintain sufficient nitrate in the root zone. We have been conducting research on ways to improve the nitrogen use efficiency of spinach and there are some promising fertilizer technologies such as controlled release fertilizers and nitrification inhibitors that show good potential for reducing nitrogen application rates to spinach while maintaining yield and quality.
Tackle Food Safety Issues
Spinach was at the center of a food safety incident in September 2006. Needless to say, the outbreak
of E. coli 0157 was a tragic event for those affected. After the incident, spinach demand plummeted and only slowly returned to pre-2006 levels. The good news is that the industry responded in a comprehensive way to address the risk factors in the field and in processing facilities.
For example, growers now examine every field prior to harvest looking for signs of animal intrusion, as well as follow a long list of food safety practices. Shippers also have procedures in place to test each lot of spinach and stop shipment of any that test positive for microbial contamination.
In all, the spinach industry has adjusted to many challenges over the years. It is a dark-green leafy vegetable associated with a healthy diet. The industry has been capable of addressing and responding to production challenges, as well as challenges with water quality and food safety.