In 1947 the USDA ARS, Beltsville, Maryland began a spinach breeding program led by Henry A. Jones. This program hoped to introduce improved varieties and F1 hybrids adapted to the Arkansas, Oklahoma and Texas production region. Henry Jones organized a research team that included Bruce Perry, Horticulturist, Texas Agricultural, Station, Crystal City, Texas; D. M. McLeon , Plant Pathologist, ARS, Mt. Vernon, Washington; H. H. Vose, Horticulturist, Arkansas Agricultural Experiment Station, Van Buren, Arkansas; E. D. Delwich, Del Monte Corp., San Leandro, California and Crystal City, Texas. Several seed company personal most, notably Robert McDonald, Alf Christianson Seed Company, Mt. Vernon, Washington, cooperated with the research efforts.
In 1955 Jones, McLeon and Perry released "Early Hybrid 7." This semisavoy was the first downy mildew resistant F1 hybrid spinach. (Development of F1 Spinach Hybrids Webb, R. E. 1976 HortScience Vol 11(6):546. Jones retired in 1957 and released several downy mildew resistant breeding lines to the seed industry which they used to produce their own F1 hybrids. The USDA breeding program was turned over to R. E. Webb when H. A. Jones retired and the relationship with Texas and Arkansas continued which led to the release of 'Dixie Market' in 1957 by the USDA and Texas AES as well as 'Hybrid 612' in 1961 by the USDA, Arkansas AES and Texas AES. (ASHS vegetable variety names, 1969)
Source: "A HISTORY OF THE TEXAS WINTERGARDEN SPINACH INDUSTRY: 1918 - 2008," by Drs. Frank J. Dainello and Teddy Morelock, formerly Extension Horticulturist and Plant Breeder at Texas A&M University and the University of Arkansas, respectively.