Field assessment of microbial inoculants to control Rhizoctonia root rot on wheat

Abstract

One sentence summary: Microbial strains applied as seed coatings were assessed in the field for control of Rhizoctonia root rot on wheat. AbstractRhizoctonia root rot caused by Rhizoctonia solani AG8 is a major disease in dryland cereal crops. Previous research identified a suite of microbes using in planta bioassay screening that are effective as seed-coated inoculants for control of Rhizoctonia root rot on wheat. This paper assessed 23 strains in fields in Australia with a history of naturally occurring R. solani AG8. Due to the patchy nature of Rhizoctonia root rot in the field, a 2-phase split-plot field trial system was used to allow comparison for disease control efficacy in the same disease space. Seed applied strains were first assessed for their ability to reduce Rhizoctonia using 'microplots' which compare adjacent treated and untreated one metre rows. Up to 10% increases in plant growth and a 32% reduction in root disease was measured at eight weeks after sowing. Selected strains were then assessed in 20 m six row (3+3) split plots for their effects on early season wheat growth and root damage and for grain yield. A Paenibacillus and a Streptomyces strain were identified which were able to reduce root damage by 20% and 32% and increase grain yield by 4.2% and 2.8%, respectively, compared to untreated controls. The current best registered chemical control for Rhizoctonia root rot reduced root disease by 35% and increased yield by 3.0% in the same trial.

Beneficial Plant Microorganisms Affect the Endophytic Bacterial Communities of Durum Wheat Roots as Detected by Different Molecular Approaches

“…Moreover, wheat plants grown in soil contaminated by the pathogenic fungus Rhizoctonia solani , inoculated with Streptomyces sp. F5, showed lower root damage and higher grain yield, compared to untreated controls (Barnett et al, 2019). Species of Rhodococcus inoculated in wheat showed interesting PGP activities, increasing straw and grain weights, compared to non-inoculated control (Basheer et al, 2016), while some isolates from wheat rhizosphere enhanced plant sulphur availability by desulfonating carbon-bound sulfonate-sulphur (Schmalenberger et al, 2009).…”

Decoding Wheat Endosphere–Rhizosphere Microbiomes in Rhizoctonia solani–Infested Soils Challenged by Streptomyces Biocontrol Agents

“…(Franco et al, 2016) described as biocontrol agents (BCA) 1, 2, and 3, respectively, were used in this study. BCA1, BCA2, and BCA3 had previously reduced Rhizoctonia root rot in both pot bioassays and in the field and have demonstrated in vitro inhibition against R. solani (Barnett et al, 2017; Barnett et al, 2019). The strains were identified by 16S rRNA gene sequencing and stored in culture collections of endophytic bacteria kept at Flinders University.…”

“…Rhizoctonia root rot is difficult to control due to its wide host range (Cook et al, 2002), lack of commercially available resistant cereal cultivars, and increased prevalence in direct drill or minimal tillage practices (Schillinger and Paulitz, 2006). Current options for partial control include strategic tillage below seeds (Roget et al, 1996), removal of the green bridge with herbicide timing (Roget et al, 1987; Babiker et al, 2011), rotation with non-cereal crops (Angus et al, 2015), and in-furrow chemical fungicide treatments (Roget et al, 1987), and more recently, by using biocontrol-coated seeds (Franco et al, 2007; Barnett et al, 2019). Currently, the estimated cost of control measures is A$106 million annually (Murray and Brennan, 2009).…”

Formulation of Trichoderma asperellum TV190 for biological control of Rhizoctonia solani on corn seedlings

“…Field applications of Trichoderma spp. have demonstrated a positive effect on biocontrol of R. solani (Barnett et al 2019). However, field environmental conditions are still one of the main limitations for the use of biocontrol agents (Bashan et al 2014).…”