<i>In vitro</i> evaluation of <i>Trichoderma</i> isolates for the control of sorghum anthracnose (<i>Colletotrichum</i> 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 AU-97 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.