Differential susceptibility of barnyard grass (Echinochloa crus-galli var. crus-galli) ecotypes to Exserohilum longirostratum

Abstract

Ten barnyard grass (Echinochloa crus-galli var. crus-galli) ecotypes collected from several locations in Malaysian and Indonesian granaries were tested for variation in their susceptibility to the leaf blight pathogen (Exserohilum longirostratum). Four phenological growth stages of the ecotypes were sprayed with E. longirostratum at the rate of 1 × 107 conidia mL−1 under glasshouse conditions. The results of the study showed that plants inoculated with 1 × 107 conidia mL−1 and exposed for 24 h dew periods were severely infected and the percentage dry weight reduction of all ecotypes significantly increased. The 1–2 and 2–3-leaf stage plants were completely killed within 6 days after inoculation. However, susceptibility reactions among the ecotypes were observed at the 4–5-leaf stage, while the 6–7-leaf stage was resistant. The ecotypes, K-02, PK-04, KN-02, CJ-01, and L-01, were the most susceptible ecotypes as indicated by a higher area under disease progress curve value. The apparent disease progress rates for these ecotypes were significantly faster compared to the other ecotypes. The dry weight reduction among the four growth stages was variable. These findings show that the 1–2 and 2–3-leaf stages are the most susceptible, while the 6–7-leaf stage was resistant. This study has confirmed that a variable response to the fungal pathogen occurred within an intraspecific barnyard grass collection.