Relating yellow sugarcane aphid, Sipha flava, damage characteristics to resistance of sorghum

The yellow sugarcane aphid, Sipha flava (Forbes), is a serious pest of sorghum, Sorghum bicolor (L.) Moench, in the United States. The aphid purples the leaves and can kill seedlings within a few days, yellow the leaves of older plants, or lodge plants before harvest. Yellow sugarcane aphids were grown on ‘Tx 399 x RTx 430’ sorghum in cages in a greenhouse. To determine the progression of damage, sorghum at the two true-leaf stage was infested with 10, 20, 30, or 40 aphids per plant. The aphids were allowed to feed on the plants for 10 days. Damage was assessed and plant growth was measured each day. Data from this study will enable better understanding of the growth of the plant during infestation and the progression of damage caused by yellow sugarcane aphids. A second study related the color of sorghum leaves damaged by yellow sugarcane aphids to resistance. Plants of ‘Tx399 x RTx430’ sorghum at different developmental stages were each infested with 20 aphids. The aphids were allowed to feed on the plants for two weeks in cages. The aphids were removed and plant biomass was determined. The point was determined where the purpling effect caused by yellow sugarcane aphids on leaves was tolerated by the plant. These data will provide information on what sorghum growth stage can resist yellow sugarcane aphids. Both studies will provide information on this little-studied but seriously damaging pest and enable better management of yellow sugarcane aphids in sorghum.