An Aeroponics System for Investigating Disease Development on Soybean Taproots Infected with Phytophthora sojae. R. E. Wagner, Department of Plant Pathology, University of Illinois, Urbana-Champaign 61801. H. T. Wilkinson, Department of Plant Pathology, University of Illinois, Urbana-Champaign 61801. Plant Dis. 76:610-614. Accepted for publication 12 December 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0610.

Pathogenesis on taproots of soybean (Glycine max) plants infected with Phytophthora sojae was investigated nondestructively with an aeroponics system. The main feature of the system is accessibility to the roots for direct observations, measurements, and application of inoculum. Lesion expansion on the taproots of the cultivar Corsoy was more rapid at 25 C than at 15 C. Lesion length after compatible interactions on the cultivars Corsoy, Sloan, and Agripro 26 was 8.0, 6.8, and 4.5 cm at 15 C and 13.5, 11.1, and 7.2 cm at 25 C, respectively, 9 days after inoculation. Cultivars were evaluated effectively for single-gene resistance based on the length and type of lesion formed 4 days after inoculation. Cultivars containing the genes Rps7 or Rps1 were susceptible, and cultivars containing the genes Rps1-b, Rps1-c, Rps1-d, Rps2, Rps3, or Rps6 were resistant to race 3 of the fungus.