Biodisinfestation with Organic Amendments for Soil Fatigue and Soil-Borne Pathogens Control in Protected Pepper Crops

Soil-borne diseases and soil fatigue cause relevant economic losses in greenhouse pepper crops from Spain, not only in the South-eastern Mediterranean region but also in the Northern areas with a humid temperate climate. The main soil phytopathological problems in the South-east are the oomycetes Phytophthora parasitica and P. capsici, the nematode Meloidogyne incognita and the soil fatigue by non-pathogenic Fusarium species proliferation. The main problems in the North are P. capsici, P. cryptogea and Verticillium dahliae. The mechanisms involved in disease suppression by organic amendments and the management strategies for the control of protected pepper crops, soil-borne diseases and soil fatigue are reviewed. Biosolarisation provides an effective and stable strategy for soil-borne pathogens control and the mitigation of soil fatigue. When biosolarisation is repeated, its effectiveness against fatigue and pathogens increases either by providing direct action against fungal microbiota and/or increasing plant health through the improvement of soil chemical and physical characteristics. Increase in macro-micronutrients and water infiltration capacity and decrease in apparent density and compaction are among the improvements in soil characteristics that are related to a crop production increase. Biosolarisation combined with organic amendments improves the soil physical characteristics, specifically in relation to the control of Phytophthora root rot which is more important in compact clay soils than in well-ventilated soils with adequate drainage. In recent years numerous alternatives for chemical disinfections have been studied, and of these, those based on organic amendments alone or in combination with solarisation seem to be the most promising (Guerrero et al. 2013) in intensive protected horticultural crops.