With the aim of identifying and! green algae and pathogenic possible to find a method of chemical management to reduce the harmful effect on seedlings of Nicotiana tabacum. black variety, this research was conducted between January to March 2000 in the Juan Guerra District, in the San Martin region located at a latitude south of 061130 'west longitude 76030' to 232 m. s. n. m, at the premises of the tobacco company seedbed of Peru S. A. Under completely randomized block design (DCA} with 15 treatments, including the control without pesticides, with 4 replications 5 7 pesticide applications (6 fungicides and 1 disinfectant) it was performed. Copper sulfate 1.5 and 3.0 %. Captan and 2.0% or 1.0, metalaxyl + mancozeb 1.5 and 3.0% or copper oxychloride and 2.0% or 1.0, thiophanate methyl + thiram 1.0 and 2, 0% or fentinacetato 0.75y1.5 °, and quaternary ammonium and 3.5 to 1.75% or all form...