Evaluation of culture media for growth and sporulation of Phytophthora colocasiae Racib., causal agent of taro leaf blight

Abstract

Phytophthora colocasiae was recently the most important pathogen of taro (Colocasia esculenta) in Cameroon and no information is yet available on its culture on common media. Six artificial media, V6 juice agar, V8 juice agar, V8m juice agar, potato dextrose agar, onion agar and taro leaf agar were assessed in vitro to determine the growth characteristics of the pathogen. After isolation of the pathogen on V6 juice agar, mycelial disks from pure culture were placed on each culture media and incubated at 24 oC for up to 21 days. After 7 days, colony diameter was highest on V6 juice agar (64 mm), followed by V8-m juice agar (57 mm), onion agar (55 mm), V8 juice agar (54 mm) and potato dextrose agar (54 mm). Sporulation was highest on V6 juice agar (18 x106 sporangia/ml) and V8 juice agar (17 x 106sporangia/ml) after 21 days of incubation. P. colocasiae grows for 3-7 days in all the media tested and produces sporangia in some of the media after two to three weeks under laboratory conditions. V6 juice agar and V8 juice agar were the best media for isolation, growth and sporulation of the pathogen and can be recommended for the culture of the pathogen.