Vargas Hoyos, Harold AlexanderGilchrist Ramelli, Elizabeth2015-08-242015-08-242015-08-241794-4449http://hdl.handle.net/10567/1360Introduction. Trichoderma asperellum strain T109 has shown great antagonism activity in vitro against phytopathogenic fungi. However, it is necessary the real understand of this strain into spatial organization in soil under in vitro and field conditions to know the population density. Objective. The aim of this study was to evaluate different inoculum concentrations and frequencies of application in Trichoderma asperellum T109 bioavailability. Materials and methods. Spore suspensions containing 1x106 and 1x108 conidia.mL-1, were evaluated under controlled laboratory and field conditions, with different application times. We used the technique of Petri plate count for determination of CFU.g-1 of soil. Results. The T109 bioavailability was affected by the frequency of application and highly significant (p<0.001) for the initial concentration of inoculum. The last sampling under in vitro conditions showed that the concentration of 1x106 conidia mL-1 was significantly different (p<0.001) when compared to 1x108 conidias. mL-1, yielding maximum value of CFU.g-1 of soil for every 4 days of application. For field conditions, we obtained significant differences (p<0.001) when the concentration of 1x108conidias mL-1 and application of 7 days were tested concomitantly. Conclusions. We can determine that the population density of T. asperellum T109 is important in the establishment of the fungus in the soil.esCorporación Universitaria LasallistaTrichoderma asperellumIn vitroDensidad de poblaciónArticle