First report of root rot caused by Pythiumspp. on chickpea in South Africa

Abstract

Chickpea is a relatively new crop in the NE South Africa. High incidences of plant death were observed in an experiment that was established in 2012 in Mziniti, South Africa to assess the agronomic performance of 66 elite chickpea lines from International Crop Research Institute for Semi-Arid Tropics. Infected plants showed signs of root rot. Therefore this study aimed at investigating the cause of the root rot. Roots of infected plants were sampled and incubated at 25°C until colonies of the pathogen were observed. Colonies were sub-cultured with sterile soil extract and sterile leaf blades. Isolates were stored in sterile distilled water with leaf blades in screw capped 15 ml McCarthy bottles at 18°C. The pathogen was identified as Pythium irregulare based on morphological structures and species description. The isolates were inoculated on healthy potted chickpea plants and these showed root rot symptoms similar to field observation. The pathogen was re-isolated from the inoculated plants and cultured; they showed similar characteristics to the ones observed during the first isolation. This is the first report of P. irregulare incidence on chickpea in South Africa.