Duration of control of two soilborne pathogens following incorporation of above‐ and below‐ground residues of Brassica juncea into soil

Abstract

The persistence of control of primary infections caused by two soilborne fungal plant pathogens, Rhizoctonia solani and Gaeumannomyces graminis var. tritici , following the incorporation of above-ground parts (AP), below-ground parts (BP) or both (AP + BP) of Brassica juncea into soil was examined through an experiment in controlled conditions. Control was quantified by measuring disease incidence in bioassays where inoculum was introduced at different dates after the incorporation of plant residues. All types of residue showed an unexpected long-term persistence that lasted at least 13 days, while the predominant glucosinolates contained in AP (20·9 μ mol sinigrin g − 1 dry matter) and BP (2·3 μ mol gluconasturtiin g − 1 dry matter) were hydrolysed in less than 3 days. Temporal trends in the efficacy of the residues behaved mostly in a quadratic manner, suggesting that the noxious effect of residues may be attributable to the release of isothiocyanates during the first days following incorporation, but that other mechanisms are most likely to contribute to lasting persistence. Across all treatments, AP and AP + BP suppressed R. solani by 54 and 63%, respectively, and G. graminis var. tritici by 40 and 40%, respectively, compared with controls. While BP did not cause any additional detectable effect when combined with AP, they had a significant effect when incorporated alone (approximately 20% suppression of both species), suggesting the existence of a complex interaction between these two types of residue.

In Vitro Activity of Glucosinolates and Their Degradation Products against Brassica-Pathogenic Bacteria and Fungi

“…The biological effects of GSLs and GHPs have been known since the early 1990s, when several authors investigated their effects on the growth and development of bacteria (19,23), insects (24)(25)(26), fungi (27,28), and nematodes (29,30), and our knowledge about the deterrent or attractant effects of the main glucosinolates on different pests (generalists and specialists) and parasitoids is well documented. Other authors have tested the effects of GHPs and GSLs on soil pathogens by incorporating Brassica residues into soil or by testing their effect by using in vitro assays.…”

“…Bending and Lincoln (17) demonstrated the toxic properties of crucifer tissues after their incorporation into soil, which limits the growth of weeds, fungus, and nematodes. GHPs have a positive effect in reducing soil pathogens, but their persistence varies depending on the compound (17)(18)(19). Brader et al (20) reported that the accumulation of GSLs in Arabidopsis thaliana L. enhanced resistance to Erwinia carotovora (Jones) and P. syringae pv.…”

Biofumigation with Brassica plants and its effect on the inoculum potential of Fusarium yellows of Brassica crops

“…In the case of Brassica juncea it has been shown that the above-and belowground plant components produce different isothiocyanates, which show different persistence once the plant residues have been incorporated in the soil (Kirkegaard and Sarwar 1998). Motisi et al (2009) described the non-additive effect of the incorporation of leaves and /or roots of B. juncea against Rhizoctonia solani and Gaeumannomyces graminis var. tritici and suggested the existence of a complex interaction between these two type of residues.…”

“…tritici and suggested the existence of a complex interaction between these two type of residues. The toxicity of isothiocyanates or other glucosinolates-related compounds to various microorganisms has been well documented (Gamliel 2000;Bailey and Lazarovits 2003;Mazzola and Cohen 2005, Manici et al 2000, PiedraBuena et al 2006, Mattner et al 2008Motisi et al 2009). Chemicals of this group such as methylisothiocyanate, the active ingredient of metham sodium and dazomet, are widely used as soil fumigants.…”

Brassica juncea seed meal particle size influences chemistry but not soil biology-based suppression of individual agents inciting apple replant disease

“…Although the generation of biologically active ITC continues to be described as the dominant means by which diseases are suppressed in response to Brassica soil amendments, an emerging body of evidence indicates alternative modes of action (Mazzola et al 2001;Mattner et al 2008;Motisi et al 2009), certain of which are biologically mediated (Cohen et al 2005;Cohen and Mazzola 2006;Mazzola et al 2007). Brassica tissue particle size has potential to affect disease control efficacy as this will influence spatial dispersal of these materials through the soil profile.…”