FIRST REPORT OF ROOT ROT CAUSED BY PYTHIUM APHANIDERMATUM AND PYTHIUM F-GROUP ON HYDROPONICALLY GROWN PEPPER IN BULGARIA

Abstract

In September 2013 and July 2014, severe wilt symptoms were observed on mature, sweet pepper (Capsicum annum L.) plants (c. Sofijska kapiya) grown in a rockwool hydroponic system in a large-scale commercial greenhouse near Petrich, South West of Bulgaria. Examination of the wilted plants revealed progressive chlorosis of the lower leaves, severe brown and soft root rot and basal stem rot. Less affected plants showed yellow discoloration of the root system, stunted growth and lack of vigor. Approximately 25% of the pepper plants collapsed and died particularly during the fruiting period in the fi rst year of observations and more than 30% of plants died in the second year. Isolations were made from sections of roots and basal stems of pepper plants with symptoms of disease on standard, nonselective media such as oatmeal (OA), potato dextrose (PDA) or water (WA) agar media. Plates were incubated at 25°C in the dark for 7 days. Pythium spp. isolates were readily obtained from all pepper plants with disease symptoms as well as from symptomless plant roots.