IN VITRO EVALUATION OF TRICHODERMA ISOLATES FOR THE CONTROL OF SORGHUM ANTHRACNOSE (COLLETOTRICHUM SPECIES)

Abstract

Sorghum (Sorghum bicolor L.) is one of the most important
grain crops grown in Ethiopia for food security. However, the production of
sorghum is highly affected by anthracnose diseases. The present study aimed
to test, evaluate, and characterize potential biocontrol agents of Trichoderma
species against two pathogenic isolates of Colletotrichum species. Sorghum
infected leaf, sheath, stalk, and soil samples were collected from Wolkait
districts for the isolation of Colletotrichum isolates. In this study, seven
Trichoderma isolates were evaluated against two pathogenic Colletotrichum
isolates in dual culture techniques and through the production of volatile and
non-volatile inhibitors. The study examined the effect of pH and temperature
on the mycelia growth and spore yield of Trichoderma isolates. In vitro
screening results showed that the proportion of isolates with antagonistic
activities was highest for the AUC-1 isolate followed by AUC-2 isolate. The
analysis revealed that all Trichoderma isolates were highly antagonistic
against AUC-1 whereas AU-97, AU-131, AU-11, and AU-12 isolates
displayed over 75% inhibition of mycelial growth on AUC-2 isolate. Under
dual culture test, the highest mean inhibitory effect on the growth of the test
pathogens was achieved by AU-11 isolate (90.29%) against AUC-1 and AU97 isolate (81.1%) against AUC-2 while AU-32 isolate showed the lowest
mean inhibitory effect in plates as compared to the controls growing alone.