ASHS 2025 Conference

In this 2023 undercover tomato study conducted at the New Mexico State University Agricultural Science Center in Los Lunas, New Mexico, treatments included two tomato cultivars, ‘Big Beef Plus’ (indeterminate, hybrid) and ‘San Marzano II’ (indeterminate, heirloom), grown under three types of shade cloth: 1) white 15% shade, 2) white 50% shade, and 3) black 60% shade. Unshaded plants of both cultivars served as controls. Two irrigation methods were also evaluated: drip irrigation and furrow flood irrigation, each applied to half of the plots. Dependent variables included mortality rates attributed to confirmed beet curly top virus (BCTV) infection, as well as plant size, yield, and fruit quality indicators such as the percentage of fruit exhibiting blossom end rot. Preliminary data indicate expected cultivar differences in yield and susceptibility to blossom end rot. Shade treatment and irrigation method appeared to influence blossom end rot incidence, although the effects varied between cultivars. The protective effect of shade cover was pronounced. By July, 79% of the surviving, uncovered control plants tested positive for BCTV; assuming that untested deceased plants were also infected, this rate rises to 89%. In contrast, among the shaded treatments (white 15% shade, white 50% shade, and black 60% shade), 25%, 25%, and 9% of the surviving plants tested positive for BCTV, respectively, with only one untested deceased plant. These findings suggest that the shade cover, wrapped around the tomato cages, effectively limited exposure to the only known vector of BCTV. The plot thickens, however, as some shaded plants that tested positive for BCTV in July still produced over 21.9 kg of fruit per plant before the first frost in late October. These preliminary findings underscore the potential of shade structures as a viable cultural practice for mitigating BCTV impact and warrant more comprehensive investigation.