NuMex Mesa was developed by Professor Joe Corgan of the Department of Agronomy and Horticulture. In 1984, reciprocal crosses were made between NuMex BR1 and Buffalo. The F1 progenies from each cross were intercrossed in 1986 and seeds were collected from the reciprocal parents separately. Three recurrent mass selections were made in 1988, '90, and '92. For each selection, selected bulbs were intercrossed, and seed was collected separately from the two lines, until 1992, when the two lines were combined. At this point, the two lines were indistinguishable. Both Buffalo and NuMex BR1 are thought to be 100% S cytoplasm, so it is likely that NuMex Mesa has only S cytoplasm. NuMex BR1 has good bolting resistance, fair pink root resistance, and is variable for shape and scale color. Bulbs tend to be soft. Buffalo has better bolting resistance than NuMex BR1, firmer bulbs, and excellent scale and handling characteristics. However, Buffalo is highly susceptible to pink root disease. Both varieties mature about the same time, about May 20 to June 1. Criteria for selection included: bolting resistance, pink root resistance, bulb firmness, bulb shape, scale characteristics, color, single-centered bulbs, and maturity. Bolting resistance screening was done in the field from early September plantings that had more than 75% bolting. Pink root resistance screening was done in infested fields at bulb maturity. Screening for single centers was done by cutting selected bulbs transversely before planting in the fall and discarding those that were not single centered. NuMex Mesa was tested in 193, '94, and '95 as 926. In 1995, a seed increase from 926 was tested as 948.
NuMex Mesa has a deep grano-shaped bulb. The scale color is tan, similar to the NuMex BR1 parent. Bulb is significantly improved over NuMex BR1. NuMex Mesa bolting resistance is the same as Buffalo, and significantly better than NuMex BR1. The pink rot resistance of NuMex Mesa is excellent, and better than either parent. Maturity is the latter part of May. NuMex Mesa's high level of pink root and bolting resistance, permitting early planting, make it adapted to soils that are severely infested with the pink root pathogen. Suggested earliest planting date for southern New Mexico is September 20. However, on fields in which production conditions are less than ideal, growers may wish to experiment with plantings as early as September 15. Because of its excellent bulb depth, NuMex Mesa is best suited for medium to low planting densities to produce large bulbs. In high density plantings to produce pre-pack sized bulbs, some bulbs appear somewhat elongated. We expect NuMex Mesa will largely replace both NuMex Sunlite and NuMex BR1. However, growers may prefer NuMex Sunlite to produce the smaller-sized pre-pack bulbs.