Evaluation location: Texas, United States
Each entry was replicated 15 times (1 plant/rep) in 4-inch square pots using a 2:1 topsoil: sand mix. At the four true leaf stage each pot was infested with five sugarbeet root aphids. Greenhouse temperature was approximately 20oC and plants were watered as needed to keep the soil moist and prevent aphids from drowning before colonies established. Plants were allowed to grow undisturbed for six weeks. After six weeks the infestations were evaluated. Plants were removed from the pots, and the level of the infestation was determined by floating aphids out of the root mass in bowls filled with water. Level of infestation was rated between 1-4 for each plant (1 - no nymphs or adults present; 2 - nymphs present, no adults present; 3 - nymphs present, few adults present; 4 - nymphs present, many adults present). The resistant check (Ranger) rated 1.47
For an Excel (xlsx) file of Michels screening data from 1995 to 2010