A research was carry out in Palmira (Valle, Colombia) to test the solarization (poliethylene mulch). The experimental design consisted in random blocks and ten treatments obtained from the following factors combination: soil solarization during 2, 4 and 6 weeks, chemical treatrnent (Dazornet), control, all of them with and without application of rabbit manure (2 kg). The plot size was 1.44 m2. The soil was inoculated with the mixture of four isolations of Rhizoctonia solani which were pathogenics to the tomato (Tropic Variety). Temperatures of 49.7oC and 44.8oC at 5 and 10 cm deep respectively were reached in the soil under solarization treatment. The control reached temperatures of 41.6 y 38.8oC at the same depths. Rhizoctonia population was reduced to 0.8 colony formation units (C F U) per 100 g of soil in the solarization treatment, during the first experiment (september to october 1987). In the second experiment (january to february 1988) the CFU was reduced to zero. The chemical treatment reduced the CFU to zero in both experiments. The control plots showed and average of 24.6 CFU during both experiments. The number of seedlings per row and the number of healthy plants (93% in both experiments) was greater in the soil under chemical and solarization treatment than the control treatment. This showed 52.3 % and 88.7% of healthy plants in both experiments. The plots where the manure was applied the number of plants per row decreased in 3.3 (solarization) and 15.3 % (chemical), during the first experiment. The second experiment showed that the number of plants per row increased in 19.2% and 9.5% to the same treatments.