The con-centration of spores was counted under light microscope with thehemocytometer. In the treatments with Trichoderma (without T-GRAN), 1 ml of spore suspension was added per 1 dm3of the soil.The density of spores in the inoculum was: for T. virens TRS 106 –11.6 × 107ml−1; for T. harzianum TRS 59 – 10.3 × 107ml−1and forT. atroviride TRS 43 – 10.4 × 107ml−1.