SUMMARY
The aim was to confirm the depressive effect on pepper plants grown in non-disinfected soils and to ascertain the possible specificity of fatigue with the goal of establishing strategies for disinfecting soils with a broad spectrum of fumigants. Soil samples were taken from six greenhouses that had been used for different numbers of years to grow a monoculture of pepper and which received different disinfestation treatments (methyl bromide, 1,3-dichloropropene+chloropicrin, biosolarization) and one which received no treatment. Every soil sample was splitted in three fractions. The first fraction was disinfested with methyl bromide (MB), the second with steam at 120ºC by autoclaving (A), and the third was not disinfected (ND). Pepper plants were cultivated in pots. Celery and lettuce were also cultivated in the same conditions to ascertain the degree to which soil fatigue was specific. In 87.5% of the 16 soil variants, the plants cultivated in the disinfected soil fractions (MB or A) were higher than those grown in the non-disinfected fractions. However, in the case of celery and lettuce, the plants cultivated in ND were higher than those cultivated in MB or A. The results show that the fatigue accumulated in the soil of the pepper monoculture was highly specific towards this crop, suggesting that rotation with other crops is an advisable agronomic practice in order to recover the soil productive capacity.