Management of tomato foot and root rot (TFRR) by biocontrol agents with emphasis on factors affecting its effectiveness

Abstract

Management of tomato foot and root rot (TFRR) caused by Fusarium oxysporum f. Sp. Radicis-lycopersici (FORL) could be achieved by biological methods which represent an ecologically friendly strategy for the sustainable crop productivity. Among these biological methods, those using biocontrol agents (BCAs) such as bacteria or fungi able to antagonize soilborne plant pathogens or stimulate plant defenses, leading to plant protection against diseases, are of great promise (de Waard et al. Annu Rev Phytopathol 31:403-421, 1993; El-Tarabily et al. New Phytol 137:495-507, 1997; El-Tarabily. Can J Bot 84:211-222, 2006). They also represent a suitable alternative to the use of chemical pesticides. Some of these antagonistic microorganisms living in association with tomato roots showing also beneficial effects on the plant growth and nutrition are called plant growth-promoting rhizobacteria (PGPR). Consequently, PGPRs could also be used as biofertilizers and are considered as an alternative tool to chemical fertilizers. In tomato, many rhizobacteria were reported to suppress diseases caused by Fusarium and/or to lead to growth promotion and tomato yield enhancement. However, BCAs are confronted to ecological parameters that are important to be determined if one wishes to succeed in disease management. The present chapter describes tomato foot and root rot (TFRR) and main mechanisms deployed by BCAs used to suppress the disease (competition by siderophore production, antibiosis, or induced systemic resistance). As the success of biocontrol methods depends largely on biotic and/or abiotic factors, some abiotic factors influencing the biocontrol agent's fitness as well as biotic factors represented by BCA interactions with either tomato plants or FORL are discussed in relation to the performance of BCAs either in greenhouse trials and agricultural fields.