VIEW ARTICLE

Epidemiology of Rhizoctonia solani Pre-emergence Damping-off of Radish: Influence of Pentachloronitrobenzene. D. M. Benson, Former Research Assistant, Colorado State University, Fort Collins 80521, Present address of senior author: San Joaquin Valley, Agricultural Research and Extension Center, Parlier, California 93648; Ralph Baker, Professor of Botany and Plant Pathology, Colorado State University, Fort Collins 80521. Phytopathology 64:38-40. Accepted for publication 25 June 1973. DOI: 10.1094/Phyto-64-38.

Curves for the inoculum density-disease incidence relationship of Rhizoctonia solani preemergence damping-off of radish (Raphanus sativus ‘Early Scarlet Globe’) were parallel for different concentrations of pentachloronitrobenzene (PCNB). Position of the curves was significantly different with an ID₅₀ value (inoculum density required for 50% incidence of disease) of 5.2 propagules/gram of soil (p/g) for 0 µgPCNB/g soil, 11.0 p/g for 7.5 µgPCNB/g soil, 26.0 p/g for 12.5 µgPCNB/g soil and 50.0 p/g for 20 µgPCNB/g soil on a log-log basis. Synergism between R. solani propagules was suggested when transformations proposed for the inoculum density-disease incidence curve were used to analyze the data.