The quequisque is a type of herbaceous plant of the annual production type, its eating contains a strong concentration of carbohydrates and is a crop of great economic importance for Nicaraguan producers who are dedicated to this item mainly in small areas located mostly in the Autonomous Region of the South Caribbean Coast of Nicaragua (RACCS), However, this crop has been strongly affected by the disease Mal seco, which is spread mainly by the movement of soil and plant material contaminated by the pathogen that so far has been identified as Pythium myriotylum . The methodology normally used in Nicaragua in the isolation of P. myriotylum is very laborious, which leads to search for more practical methods and selective culture media to obtain pure cultures.