Preservação do inóculo de Plasmodiophora brassicae utilizando o método de congelamento

ABSTRACT The preservation of Plasmodiophora brassicae resistancestructures under laboratory conditions is difficult since this is anobligate parasite. The freezing method using an ordinary householdfreezer was tested to ensure the pathogen’s survival and thepreservation of its infective traits. Roots of different brassica speciesnaturally infected by P. brassicae , showing typical clubrootsymptoms, sampled in the same farm, located in the Pardinho County,State of Sao Paulo, were collected during different seasons and wereimmediately frozen at approximately 20°C. The treatments weredivided as follows: T1: clubroots frozen for 389 days (arugula); T2:clubroots frozen for 242 days (broccoli); T3: clubroots frozen for 21Cruz, J.C.S.; Souza, N.L.; Padovani, C.R.; Furtado, E.L. Preservation of Plasmodiophora brassicae inoculum using the freezing method. SummaPhytopathologica , v.35, n.1, p.57-59, 2009 Keywords: Clubroot, soilborne pathogen, pathogenicitydays (Chinese cabbage), and T4: control (without inoculum). Thepathogenicity tests were conducted under greenhouse conditions(25±2°C). Each plant of the susceptible variety of Chinese cabbage(Pak choi) was inoculated with 2mL of a spore suspension of eachtreatment at a concentration of 10