Evaluation of Commercial Sorghum Hybrids for Resistance to Melanaphis sacchari

In 2015 through field and growth chamber studies, Sorghum bicolor, was evaluated for resistance to, Melanaphis sacchari (Zehntner), at three locations in Louisiana.  Hybrids included a known resistant ATx2752/RTx2782, a known susceptible ATx2752/RTx430, and 14 hybrids with suspected resistance. The objective was to determine the degree of resistance among the hybrids. The field study was a split-plot design with hybrids being main plots.  One sub-plot was protected from aphid infestation by means of insecticide (sulfoxaflor), while the other was left untreated.  In addition to the field study, a seedling screening was conducted with the same hybrids in a growth chamber.  Hybrids were planted in 8-inch pots, with five seedlings per pot.  At the 2 to 3 leaf stage, seedlings were infested with ~50 aphids per plant.  Each plot was rated on a 1-9 injury scale, 17 days after infestation.  In field trials, hybrids that appeared susceptible included: ATx2752/RTx430 and DGM756B39. Hybrids that exhibited possible tolerance included: DGM77GB52, DG 765B, and R94153. Hybrids that exhibited possible antibiosis included: ATx2752/RTx2783, R84353, R9813, SP6929, SPX17514, SP7715, NKX760, P-83P17, W-844-E, and DKS37-07. Additionally, ATx2752/RTx2783, DKS37-07, R9813, R84353, SP7715, SPX17414, SPX17514, NKX760 and W-844-E exhibited significantly less feeding injury than ATx2752/RTx430 in the seedling susceptibility screening.