Nestika, RevilliaZul, DelitaMayta Novaliza, Isda2016-01-302016-01-302016-01-30wahyu sari yenihttp://repository.unri.ac.id/xmlui/handle/123456789/7834This research aims to analyze the effectiveness of Phosphate Solubilizing Bacteria (PSB) which are able to produce cyanide acid (HCN) in controlling of predominant weed in the corn plantation. This research was conducted from September to December 2014 in the Laboratory of Microbiology, Faculty of Mathematics and Natural Sciences, University of Riau. The effectiveness of PSB in controlling the growth of Ageratum conyzoides was performed by inocullating 26-selected PSB isolates into pre-germinated of those weeds based on the Kremer and Soussi with modification. The seed were sterilizedby soaking it in a solution of 95% ethanol before being inoculated with 26- selected PSB isolates. The sterilized seed were pre-germinated on the media of 1% agarose. Seeds which has been germinated were dropped with bacterialsuspension of PSB as much as 1 ml. The parameters observed were root length and shoot length of weed seedlings. The results suggested that all of PSB isolates were generally able to selectively inhibiting the growth of roots and shoots on weeds. Isolates BB-BK4 and BB-HP29 werethe most effective in controlling weed because the percentage of its reduction is 60-80%.enAgeratum conyzoidesCornCyanide acidPhosphatSolubilizing Bacteria (PSB)student Paper Post Degree