Moses K. Tokan Pengarang Mbing Maria Imakulata Pengarang Gufran Darma Dirawan Pengarang

The purpose of this study was to examine the antibacterial potency of seaweed and analyzes the ice-ice disease control through polyculture cultivation techniques. This research was conducted in two phases, namely laboratory and field study. The method used in the laboratory study is designed with a completely randomized design. The antibacterial activity assays performed with the agar diffusion method. Data of the inhibition zone diameter were analyzed by one-way analysis of variance followed by honestly significant difference test at a significance level of 5 %. Data in the field study collected base on an appearance of the thallus and the percentage of infected clumps and analyzed descriptively. Data on wet weight gain per week were analyzed by t-test. The results showed that the antibacterial of seaweed Achantophora spicifera, Caulerpa racemosa, Sargasum duplicatum and Lorencia obtusa provide a significantly different effect on the growth of isolates of Pseudomonas sp A of ice-ice disease seaweed. Achantophora spicifera showed stronger potency in inhibiting bacterial test so it was decided to be used as companion plants in biological control. The results of the field study suggest that ice-ice disease in Kappaphycus alvarezii can be controlled through polyculture techniques. The result showed that in the treatment group 0.062 % infected by an ice-ice disease, while in the control group more than 50%. Therefore polyculture techniques can be used to control the ice-ice disease.