Analysis of Environmental Variables and Carbon Input on Soil Microbiome, Metabolome and Disease Control Efficacy in Strawberry Attributable to Anaerobic Soil Disinfestation

Abstract

Charcoal rot and Fusarium wilt, caused by Macrophomina phaseolina and Fusarium oxysporum f. sp. fragariae, respectively, are major soil-borne diseases of strawberry that have caused significant crop losses in California. Anaerobic soil disinfestation has been studied as an industry-level option to replace soil fumigants to manage these serious diseases. Studies were conducted to discern whether Gramineae carbon input type, incubation temperature, or incubation duration influences the efficacy of this disease control tactic. In experiments conducted using ‘low rate’ amendment applications at moderate day/night temperatures (24/18 °C), and carbon inputs (orchard grass, wheat, and rice bran) induced an initial proliferation and subsequent decline in soil density of the Fusarium wilt pathogen. This trend coincided with the onset of anaerobic conditions and a corresponding generation of various anti-fungal compounds, including volatile organic acids, hydrocarbons, and sulfur compounds. Generation of these metabolites was associated with increases in populations of Clostridium spp. Overall, carbon input and incubation temperature, but not incubation duration, significantly influenced disease suppression. All Gramineae carbon inputs altered the soil microbiome and metabolome in a similar fashion, though the timing and maximum yield of specific metabolites varied with input type. Fusarium wilt and charcoal rot suppression were superior when anaerobic soil disinfestation was conducted using standard amendment rates of 20 t ha−1 at elevated temperatures combined with a 3-week incubation period. Findings indicate that anaerobic soil disinfestation can be further optimized by modulating carbon source and incubation temperature, allowing the maximum generation of antifungal toxic volatile compounds. Outcomes also indicate that carbon input and environmental variables may influence treatment efficacy in a target pathogen-dependent manner which will require pathogen-specific optimization of treatment protocols.

An anaerobic rhizobacterium primes rice immunity

“…S3d-f). Our results are in agreement with those of a previous study reporting a negative correlation between the relative abundance of Clostridium and that of Bacillus (Hewavitharana et al, 2021). Overall, our results suggest that oxygen is one of the key factors that determines the prevalence of Clostridium in each rhizocompartment.…”

Optimization of the Use of Industrial Wastes in Anaerobic Soil Disinfestation for the Control of Fusarium Wilt in Strawberry

“…The rise in F. oxysporum propagules could be explained by the fact that the carbon groups not consumed during treatment would enable the fungus to proliferate. It is known that pathogenic and non-pathogenic forms of F. oxysporum are competitive saprophytes, so limited substrate availability at the end of the anaerobic period is essential [ 6 ]. Therefore, a balance between the preference of F. oxysporum for a specific amendment and the need for carbon input to generate anaerobic conditions during ASD is required for good disinfestation.…”

“…Anaerobic soil disinfestation (ASD) is attracting particular interest among researchers as an alternative to the use of chemical fumigants for the management of soilborne pathogens [ 6 , 7 ]. The technique involves the addition of organic amendments to the soil, irrigation to field capacity, and covering the surface with plastic tarps to achieve reductive conditions [ 8 , 9 ].…”

Comprehensive Control System for Ginger Bacterial Wilt Disease Based on Anaerobic Soil Disinfestation

“…To improve ASD treatment, the elucidation of its disinfestation mechanism is needed. It is speculated that many factors (soil microbial community, additive organic matter, temperature, and the physical and chemical properties of the soil, among others) affect the success of ASD [42][43][44][45][46][47][48][49][50]. During ASD treatment, specific soil microorganism groups which belong to Clostridium spp.…”

“…[24,36,42,48]. Hewavitharana et al [49] reported that these kinds of materials were produced at comparatively high temperatures and suggested that this has a correlation with an increase in populations of Clostridium spp. It is also known that the degree of disinfestation differs among soil types [50], even though the same carbon sources were applied for ASD, and the correlation of soil type with the multiplication of Clostridium spp.…”