Antagonistic Test of Streptomyces sp. Against The Growth Of Pestalotiopsis sp. The Causal Agent Of Rubber Leaf Fall Diseases In Vitro

Abstract

Rubber (Hevea brasiliensis Muell. Arg) plays a significant role in Indonesia's economy. However, its production has declined due to several factors, one of which is the leaf fall diseases caused by Pestalotiopsis sp. This disease infects all rubber clones, reducing latex yield up to 45%. Therefore, sustainable yet effective and efficient control methods are needed. One of the methods is biocontrol using antagonistic microorganisms. A potential biocontrol agent is the bacterium from the genus Streptomyces, known for producing antibiotic compounds. This study aims to investigate the initial potential of Streptomyces sp. to inhibit the growth of Pestalotiopsis sp. in vitro. A completely randomized design (CRD) was employed, including four treatments, each replicated five times, two petri dishes per experimental unit and the dual culture method. Results showed that different Streptomyces sp. isolates were capable of inhibiting the growth of Pestalotiopsis sp., with the highest inhibition observed in isolate PTJ at 50.66%, producing a clear zone of 19.5 mm, with the lowest in isolate PPT at 23.98%. An overgrowth mechanism was also observed, where Pestalotiopsis sp. hyphae grow over Streptomyces sp. Furthermore, Streptomyces sp. not only has the potential to suppress plant diseases but also to enhance plant growth, including height, weight, and leaf numbers. Future research is recommended to explore in vivo potential of Streptomyces sp. in inhibiting Pestalotiopsis sp., the causal agent of rubber leaf fall disease.