May 24, 2022
USDA wishes you a happy National Asparagus Day! Americans consume over 500 million pounds of asparagus each year, and 80-90% of that is imported, mainly from Mexico and Peru. While domestic production continues to decline year-by-year, per capita consumption is growing and U.S. growers still produce 60-70 million pounds per year, mostly in Michigan, California, and Washington.
Asparagus is a perennial plant that grows from rootstalks (or rhizomes). It takes two to five years for the plant to establish; after that the sprouts (a.k.a. spears, the part people consume) are ready to harvest. The first sprouts are left to fern out into rows that look like shrubbery. Ferning builds energy reserves and a strong root system that will produce healthy yields in later years.
Once in production, a well-maintained field of asparagus can produce spears for 20 years or more. Spears emerge quickly in the springtime. To get the most tender spears, workers harvest almost daily. Each spear is hand-harvested and bundled by skilled workers using special knives.
Asparagus production has multiple pest management challenges. Asparagus beetles and aphids drive the biggest need for insecticides. Another troublesome pest is the asparagus miner, which is a maggot infesting stems. Ideally many pests are controlled after the season is over by managing populations on ferns. A common cultural tactic is to remove or burn dried ferns in the dormant season, to eliminate over-wintering habitat for pests. But under high pest pressure, growers sometimes need to spray spears in between harvests, carefully selecting tools determined by EPA to be safe.
Asparagus growers battle fungal and viral disease. Weed control is complex, especially when weeds grow within the row. Asparagus spears are sensitive to tillage and many herbicides, so it’s essential to select the best methods at the optimal timing to avoid crop injury.
For more resources on asparagus management, visit Michigan State University Entomology Department and University of California Integrated Pest Management.