IN-VITRO BIOCONTROL POTENTIAL AND MECHANISM OF INHIBITION OF INDIGENOUS TRICHODERMA ISOLATES FROM SOUTHEAST SULAWESI PROVINCE OF INDONESIA AGAINST SCLEROTIUM ROLFSII

Abstract

Sclerotium rolfsii is an important plant pathogen and causes disease in some cultivated plants especially in Southeast Sulawesi. S. rolfsii is mainly controlled by using synthetic fungicides which are hazardous to human, livestock and environment. In the present study, eleven species of Trichoderma, indigenous to Southeast Sulawesi, were tested for their in vitro efficacy against S. rolfsii to replace deleterious fungicides. The analysis of variance showed significant results of the indigenous Trichoderma spp. against S. rolfsii. in in vitro test. All the Trichoderma isolates inhibited the growth of the test fungus differently. After three days of inoculation, ST1 treatment showed the highest inhibitory ability by 55.56% but was not significantly different from the inhibitory abilities of ST2, ST3, ST5, ST6, ST7, ST9, ST10, and ST11 treatments. The treatment ST4 and ST8 gave inhibitory abilities by 25.22% and 26.11% respectively. Furthermore, the data after 4, 5, 6 and 7 days after inoculation were also significant. The ST1 (DKT isolate) treatment gave the maximum inhibition of the test fungus after all the time intervals of seven days. On the other hand, ST8 (LKP isolate) treatment gave the lowest inhibitory ability. DKT isolate of indigenous Trichoderma had the highest inhibitory ability reaching to 55.56% on third days of observation while LKP isolate had the lowest inhibitory ability of 16.67% and then decreased subsequently. the antagonistic mechanisms of Trichoderma isolates were space and nutrition competition, antibiosis, and mycoparasitism. These results showed that Trichoderma indigenous to Southeast Sulawesi had better in vitro inhibitory ability to control S. rolfsii by the above-mentioned mechanisms.