The Evaluation of the Activity of Some Algae and Their Extracts on the Control of Stem Canker of Potato Caused by Rhizoctonia solani

Abstract

This study is conducted at laboratories of College of Agriculture- university of Kufa in order to evaluate three algae Microcystis sp., spirulina eplatensis and sarconema sp. and their organic extracts against Rhizoctonia solani pathogen .The antagonistic ability of Microcystis is effective against R.sloni because it gives colony diameter 7mm , with inhibitory percentage 65% , as compared with control which gives 20mm of colony diameter .The results revealed that methanol extract was more effective in reducing the viable cells of R.solani which give 28.66 x 104 CFU/ml as compared to 32.40 x 104 CFU/ml at the control .Viable cells of R.solani are reduced with the application of Microcystis which is 26.46x104 CFU/ml as compare with spirulina platensis and sarconema which give 29.18 and 28.14x 104 CFU/ml respectively .The ethanolic extract of Microcystis sp. has the superiority of reducing colony diameter of R.solani , when gives inhibitory zone 26mm as compared with acetone as an extract of the same alga which gives inhibitory zone 20mm