`Valprize': A Butterhead Lettuce Cultivar for Southern Texas

Abstract

Lettuce production in the Lower Rio Grande Valley (LRGV) of southern Texas has fluctuated from a high of 1882 ha in 1979 to a low of 564 ha in 1986. Since 1986, production has rebounded to just > 1000 ha in 198990 season, with mostly crisphead type cultivars. There are three planting periods: midSeptember to early October; mid-October to mid-November; and late November to midDecember. Each planting period requires specifically adapted cultivars to maintain shipments from November through April. Butterhead types are occasionally integrated into the cropping system, but often fail to produce a salable product because of diseases and bolting. The purpose of our breeding program was to develop a larger butterhead lettuce adapted to the LRGV. Primary importance was placed on resistance to premature bolting and tipbum. Secondary emphasis focused on resistance to Texas races 5 and 6 of downy mildew (Bremia lactucae Regl.), which is a sporadic problem in the region. An additional objective was to enlarge the array of adapted lettuce cultivars available to growers in southern Texas. ‘Valprize’ was developed as a re-