SCREENING INDIGENOUS RHIZOSPHERIC ACTINOMYCETES AS BIOCONTROL AGENT TOWARD WHITE ROOT FUNGUS IN NUTMEG PLANTS IN SOUTH ACEH

Abstract

White root disease caused by the white root fungus group is one of the diseases that infects nutmeg plants with potential losses reaching 70% of total production. The presence of fungi in the rhizosphere allows infection to occur through plant roots. Many people have been able to control this disease, including using inorganic pesticides. Inorganic pesticides in their application have been proven to be able to reduce losses or damage, so that currently the role of pesticides cannot be ignored in achieving production targets. But on the other hand, inorganic pesticides are generally toxic and have a negative impact on the environment. Considering the possible side effects, it is necessary to develop biological pesticides that are more environmentally friendly. Among the biological control agents known to control fungal group pathogens is the Actinomycetes group. Actinomycetes are a group of microorganisms that are capable of producing secondary metabolites. This metabolite has the potential as an ingredient to control fungal phytopathogens such as white root fungus. This study aims to isolate and screen actinomycetes isolates that have antagonistic potential against white root fungus. The research stages consisted of taking samples in the rhizosphere, isolating actinomycetes, purifying actinomycetes on agar media and Bioassay of antagonism potential toward white root fungus. The research results obtained 22 isolates with 17 isolates showing antagonistic potential against white root fungus. A total of 4 isolates, namely STJ 10, STJ 06, STS 07 and STS 26, were known to have very strong antagonist potential with respective inhibitory power values of 31.84; 21.68; 21.36 and 21.97 mm.