Fusarium-wilt suppressive soils from the Châteaurenard region : review of a 10-year study

Abstract

This paper presents the main results obtained while studying the fusarium-wilt suppressiveness of Chateaurenard soil. Experimental data are discussed in relation to the main theories developed to explain the phenomena ot soil suppressiveness to fusarium wilts. This suppressiveness, based fundamentally on microbiological interactions, relies on the complementary association of a general mechanism of competition for nutrients between the whole soil microflora and the entire Fusarium population and intrageneric competition between pathogenic and non-pathogenic Fusarium. This research has led to new approaches for microbiological control of fusarium wilts.Additional key words : soil receptivity, competition for nutrients, general suppression, specific suppression, biological control. RÉSUMÉ La résistance des sols de Châteaurenard aux fusarioses vasculaires : bilan de 10 années de recherche.Cet article présente de manière synthétique les résultats auxquels ont donné lieu les recherches consacrées à la résistance des sols de Châteaurenard aux fusarioses vasculaires. Les résultats expérimentaux sont discutés par rapport aux principales théories développées pour expliquer les phénomènes de résistance des sols aux fusarioses vasculaires. Cette résistance, de nature fondamentalement microbiologique, repose sur l'association complémentaire d'un mécanisme général de compétition nutritive entre l'ensemble de la microflore tellurique et la population fusarienne et d'un mécanisme spécifique de compétition intragénérique entre formes pathogènes et non pathogènes de H'usarium. Ces recherches suggèrent de nouvelles voies pour élaborer des procédés de lutte microbiologique contre les fusarioses vasculaires.

Phenazine antibiotics produced by fluorescent pseudomonads contribute to natural soil suppressiveness to Fusarium wilt

“…Densities of indigenous populations of nonpathogenic F. oxysporum were shown earlier to be much higher in Fusarium wilt suppressive than in conducive soils (Alabouvette, 1986). Additional suppression by the combination of non-pathogenic F. oxysporum strain Fo47 and specific isolates of fluorescent pseudomonads was reported earlier (Lemanceau and Alabouvette, 1991;Lemanceau et al, 1992, Duijff et al, 1999 and proposed to account for the efficacy and stability of the natural suppressiveness (Lemanceau et al, 2006).…”

“…Fusarium-wilt suppressive soils substantially limit the disease incidence or severity, but are not suppressive to diseases caused by non-vascular Fusarium species or other soil-borne pathogens (Alabouvette, 1986). The microbiological nature of the disease suppression in Fusarium-wilt suppressive soils was unequivocally shown by a range of approaches, including treatments with moist heat, methylbromide or g-irradiation leading to loss of soil suppressiveness, and by experiments in which suppressiveness was transferred to wilt-conducive soils by mixing small amounts (0.1-10% wt/wt) of the suppressive soil into the conducive soil (Scher and Baker, 1980;Alabouvette, 1986;Weller et al, 2002). Fusariumwilt suppressive soils maintain their activity when brought into the greenhouse or laboratory, which greatly facilitates the identification of the microorganisms, mechanisms and genes involved in disease suppressiveness.…”

“…Among the bacterial and fungal genera proposed to contribute to Fusarium wilt suppressiveness are Alcaligenes (Yuen and Schroth, 1986), Trichoderma (Sivan and Chet, 1989), Actinomycetes (Amir and Amir, 1989), Pseudomonas (Kloepper et al, 1980;Scher and Baker, 1982; and non-pathogenic F. oxysporum (Alabouvette, 1986;Larkin et al, 1996). Detailed studies on Fusarium-wilt suppressive soils from Châteaurenard (France) and Salinas Valley showed that the suppressiveness was attributed, in particular, to the activity of non-pathogenic F. oxysporum and fluorescent pseudomonads (Scher and Baker, 1982;Alabouvette, 1990;Lemanceau and Alabouvette, 1991;Duijff et al, 1999).…”

Low Water Availability Enhancing Soil Receptivity to Fusarium Pathogen: Case of Root Rot on Mulberry

“…This causes the soil to become conducive or receptive to F. oxysporum. Soil receptivity to a soil-borne pathogen reflects the capacity of a soil to allow a pathogen to establish, develop, persist, and express its pathogenicity on host plants [18]. On the contrary, increased water content with water near to or at field capacity correlating with a high population of microorganisms other than the pathogen.…”

“…and the soil pH of 5.6 was more suitable for development of fungi than of bacteria [19]. A range of textures of soil could be suppressive to Fusarium such as sandy to loam soil [16], but the most Fusariumsuppressive soils are clay soils [18]. The soil under study in our research was clay, which is likely to have the potential to be managed for long lasting suppression of Fusarium.…”