Lettuce is perhaps the most widely consumed vegetable in the United States yet its commercial production is extremely restricted. Although limited commercial acreage can be found in several states such as Colorado, Texas, and Florida, Arizona, and California dominate US production accounting for more than 95% of the US lettuce production.
Most production is focused on three principle lettuce types:
- Crisphead (iceberg)
- Leaf lettuce
In California, lettuce is ranked as the 5th most important agricultural commodity with a gross value of $1.96 billion (California Agricultural Production Statistics 2016). In Arizona, the importance of lettuce as agricultural commodities is even more striking: The lettuce crop is ranked as the highest valued crop commodity with a gross value of $800 million or roughly 30% of the state's agricultural economy (Arizona Agricultural Statistics Service 2008).
Between these states, lettuce production occurs year-round and is primarily grown in three regions depending on the season. In summer, production occurs in the Salinas Valley and other coastal valleys in California, and in fall and spring production occurs in the San Joaquin Valley, CA. In winter, virtually all US production of the 3 lettuce types occurs in the deserts of Arizona and California, and is a critical industry for this region's economic health (California Agricultural Statistics Service. 2006; National Agricultural Statistics Service).
Disease management is a principle activity for growers of all types of lettuce as viral, bacterial, and most importantly, fungal diseases can seriously impact quality and yield. Many management strategies are based on chemical applications as these methods often provide the only level of control acceptable to the industry.
For a complete list of these diseases, visit the American Phytopathological Society website.