Leaf Lettuce: An Alternative for Virginia’s Eastern Shore*

Romaine and Boston lettuce (Lactuca sativa L., Compositae) were identified as economically feasible alternative crops for eastern Virginia (Sterrett et al. 1996; Kalo 1997). Although lettuce is one of the most widely consumed vegetables, much of the production is concentrated in western states. Per capita consumption of leaf lettuce has increased from a low of 1.1 kg in 1986 to an estimated 3.4 kg in 1999 and currently represents 24% of total head lettuce consumption (USDA 1999). Although neither Boston nor Romaine lettuce is expected to become a dominant crop on the Eastern Shore, successful production and marketing of lettuce will increase growers’ options for crop diversification. Growers of new or non-traditional crops are likely to experience one or more production and marketing problems, including reliance on expensive hand labor, lack of registered plant protective chemicals, or effectively selling in non-traditional markets or easily saturated markets (Reiners 1992). Other areas are examining the market potential of non-iceberg types of lettuce grown on plastic mulch, including North Carolina (Scherer 2000) and Alabama (Simonne et al. 1997). Traditionally, direct-seeded lettuce has been overseeded and hand-thinned after plant emergence to achieve the desired plant population. Lettuce yield is directly proportional to plant population and plant size uniformity (Seale et al. 1994). The cost of production could be reduced by precision seeding but near perfect plant populations are needed for lettuce to be economically feasible in Virginia (Kalo 1997). In preliminary studies, reduced plant establishment was associated with soil crusting prior to emergence (Sterrett and Savage, unpubl. data). The Bojac sandy loam soil (mixed, thermic Typic Hapludult) that is predominant on the Eastern Shore is known for crusting, particularly after heavy rainfall. Banding vermiculite directly over broccoli [Brassica oleracea (Italica group)] seed was recommended to improve plant emergence in southeast Virginia but was only successful with adequate soil moisture (C.R. Odell, pers. commun.). Ellis (1965) found improved emergence following application of either sand or perlite, but the lighter weight perlite was easier to apply. Seale et al. (1994) reported improved plant emergence using calcined montmorillonite clay fired at high temperature compared with the same clay fired at low temperature or a peat-vermiculite mix, which were both water absorbent. Locally available organic by-products could reduce production costs, but need to be evaluated for effectiveness in promoting stand establishment of direct-seeded lettuce. Sand becoming embedded in the crown of the plant is another a serious concern for lettuce growers on the Eastern Shore (Sterrett and Savage, unpubl. data). Alternative management strategies may reduce soil movement associated with rainfall events, thereby facilitating the production of leaf lettuce as a new crop for this region. The overall goal was to examine the production feasibility of Boston and Romaine type lettuce in eastern Virginia and to determine the impact of production practices on product quality. Strategies that are not effective, or are detrimental to product quality, need to be identified to minimize potential grower risk. Therefore, the objectives were to 1) evaluate influence of physical soil anti-crustants on plant emergence and yield of direct-seeded lettuce, and 2) examine effect of alternative management strategies on sand movement into and retention in lettuce crowns.