Several preplant soil fumigation treatments were repeated over a period of three years on strawberry (Fragaria ×ananassa Duchesne) crops, at two different places in the province of Huelva (southwestern Spain). The influence of these treatments on Trichoderma soil populations and on populations of soilborne pathogens was examined every year by isolating soil onto selective media. No strawberry pathogens were detected but Trichoderma soil populations increased each year after the treatment. Significant differences were noted between the treatments and also compared to the control. The largest populations were observed after treatments with methyl bromide and chloropicrin, and so resulting in a higher production. Chemical name used: trichloronitromethane (chloropicrin).