Role of substrate decomposability and volatile fatty acids in anaerobic soil disinfestation activity against <i>Sclerotinia sclerotiorum</i>

Shrestha, Utsala; Collins, Ron L.; Swilling, Keagan J.; Ownley, Bonnie H.; Butler, David M.

doi:10.17660/actahortic.2020.1270.8

Cited by 5 publications

(6 citation statements)

References 31 publications

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“…Total marketable tomato fruit yield data was collected 2-3 times each week from mid-June to mid-July. Shrestha et al (2020a) and ASD treatments included a range of amendments based on substrate bioavailability (sucrose, corn starch, pine shavings, each with feather meal added to bring to a ∼30:1 C:N amendment C:N ratio and ∼3.4 mg C g −1 soil) which were compared to an anaerobic control with feather meal amendment only (Table 1). The design of the experiment was a split plot randomized complete block design with six replicates.…”

Section: Trial 3 On-farm High Tunnel Trial Of Tomato Crop Performancementioning

confidence: 99%

“…Data for soil pH and soil anaerobic conditions for trials 1, 2 and 4 have been published previously (Shrestha et al, 2018a(Shrestha et al, , 2020a). Here we summarize the overall results briefly to provide an overview of the environmental conditions during soil treatments (see Supplementary Table 1).…”

Section: Soil Characteristicsmentioning

confidence: 99%

“…The ASD process relies on the bioavailability of organic matter in ASD amendments, which increases soil microbial respiration leading to strongly anaerobic soil conditions that facilitate shifts to anaerobic microbial decomposition and the formation of anaerobic decomposition metabolites (Shennan et al, 2014). Amendment C:N ratio, rate, and decomposability all potentially affect these microbial decomposition dynamics (Sinsabaugh et al, 2013;Spohn, 2015;Truong and Marschner, 2018), potentially affecting ASD treatment effectiveness for pathogen control (Shrestha et al, 2018a(Shrestha et al, , 2020a. At the same time, soil amendments and their biochemical composition potentially impact a range of soil chemical, physical, and biological properties (Inglett et al, 2005;Butler et al, 2014a) and of these, changes affecting soil nutrient availability are especially important in affecting crop performance post-ASD treatment (Butler et al, 2014a;Di Gioia et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Amendment Properties Affect Crop Performance, Leaf Tissue Nitrogen, and Soil Nitrogen Availability Following Soil Treatment by Anaerobic Soil Disinfestation

Shrestha

Swilling

Butler

2021

Front. Sustain. Food Syst.

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Efficacy of anaerobic soil disinfestation (ASD) for soilborne plant pathogen suppression is strongly influenced by soil environment and organic amendment attributes. At the same time, these factors influence soil nutrient availability, crop nutrition, and crop performance, but published information on ASD amendment property effects, including carbon to nitrogen (C:N) ratio and C substrate bioavailability, on crop performance and soil nutrient availability is limited. We evaluated ASD amendment effects on soil N availability, crop N status, and solanaceous crop performance in a series of trials: (1) greenhouse/growth chamber study of amendments (primarily molasses/soybean hulls and wheat bran) formulated at 10:1, 20:1, 30:1 and 40:1 C:N ratios (4 mg C g−1 soil), (2) field study with molasses/soybean hull-based amendments at equivalent C:N ratios/C rates (3) on-farm study with molasses/soybean hull-based amendments (4 mg C g−1 soil) compared to grower-standard control, and (4) field study of labile to recalcitrant amendment substrates at 30:1 C:N ratio (~3.4 mg C g−1 soil). ASD amendment C:N ratio strongly influenced soil inorganic N and the lowest (10:1) ratio was associated with highest soil inorganic N at ASD treatment termination in both trials 1 and 2, which often persisted into the cropping phase. Accordingly, the lowest amendment C:N ratio was also associated with the highest biomass (trail 1), leaf tissue N (trial 2), and crop yield (trials 1, 2) among treatments, even with application of recommended fertigation rates to all treatments in the field study. In trial 3, ASD treatment induced higher soil inorganic N and crop yield than the control, but no differences were observed in plant tissue N. In trial 4, more decomposable ASD substrates reduced soil inorganic N at ASD treatment termination, with the highest soil inorganic N associated with the most recalcitrant amendment, but there was no effect on crop yield. ASD amendment C:N ratio, and to a lesser extent, amendment decomposability, exert a strong influence soil inorganic N and crop performance. Optimization of ASD treatments for disease management will require simultaneous optimization of crop nutrition practices to facilitate more holistic, less confounded assessment of crop performance and to facilitate recommendations for grower adoption.

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Section: Trial 3 On-farm High Tunnel Trial Of Tomato Crop Performancementioning

confidence: 99%

Section: Soil Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Amendment Properties Affect Crop Performance, Leaf Tissue Nitrogen, and Soil Nitrogen Availability Following Soil Treatment by Anaerobic Soil Disinfestation

Shrestha

Swilling

Butler

2021

Front. Sustain. Food Syst.

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“…Concentrations of VFA were selected based on previous studies (4, 8, and 16 mmol/kg soil) to represent a typical range of the VFA concentrations present in soil during the ASD process (e.g., Shrestha et al, 2020a). Working solutions were created by combining reagent-grade concentrated VFA with autoclaved double deionized water to achieve concentrations of 0.027, 0.053, and 0.107 M. These concentrations were equivalent to final soil concentrations of 4, 8, and 16 mmol/kg dry soil given treatment application rates.…”

Section: Methodsmentioning

confidence: 99%

“…The VFAs are then readily metabolized by aerobic microbes during soil oxidation that would follow ASD treatment (Adeleke et al, 2017). There are multiple reports that ASD treatment induces relatively high soil concentrations of acetic and n-butyric acid (Momma et al, 2006;Runia et al, 2014;Huang et al, 2015;Shrestha et al, 2020a). These compounds are likely an important factor in control of inoculum of some soilborne fungal plant pathogens, including Fusarium oxysporum and Verticillium dahliae, and plant parasitic nematodes such as Pratylenchus penetrans and Pyrenochaeta terrestris (Blok et al, 2000;Shinmura, 2004;Browning et al, 2006;Momma et al, 2006;Oka, 2010;Runia et al, 2014;Huang et al, 2015), but it is unclear how VFAs and carbon amendments affect viability of large fungal sclerotia (like those of Athelia rolfsii) or potential mycoparasites of sclerotia-forming plant pathogens, such as Trichoderma or Mucor spp., during ASD treatment in field (i.e., non-autoclaved) soils.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Anaerobic Soil Disinfestation: Volatile Fatty Acids Reduce Viability of Athelia (Sclerotium) rolfsii Sclerotia in Acidic Soil Conditions and Have Limited Effects on Endemic Trichoderma spp.

Swilling

Shrestha

Ownley

et al. 2021

Front. Sustain. Food Syst.

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Volatile fatty acids (VFAs), such as acetic and n-butyric acid, released during anaerobic decomposition of organic soil amendments during anaerobic soil disinfestation (ASD) likely play a role in soilborne plant pathogen inoculum suppression. However, research is limited on the direct effects of soil VFA exposure on fungal plant pathogen inoculum, effects on pathogen antagonists such as Trichoderma spp., and the role of soil microbial VFA metabolism on reducing exposure effects. The present study addresses these limitations through a series of studies evaluating the effects of VFA (acetic or n-butyric acid), VFA concentration (4, 8, or 16 mmol/kg soil), soil sterilization by autoclaving, and soil amendment on the viability of Athelia rolfsii (Sclerotium rolfsii) sclerotia post VFA exposure, and soil populations of Trichoderma spp. HCl and water-only controls were included. After 4-days exposure in an acidic, anaerobic environment, sclerotial viability, and colonization by culturable fungi or bacteria were assessed with standard procedures. Greenhouse experiments were similarly conducted to evaluate endemic soil populations of Trichoderma spp. following soil exposure to VFAs and Trichoderma spp. populations assessed with standard soil dilution plating onto semi-selective medium. Sclerotial germination was generally reduced by soil exposure to acetic (35.1% germination) or n-butyric (21.9% germination) acids compared to water (74.3% germination) and HCl (62.7% germination). Germination was reduced as VFA concentration increased from 4 to 8 and 16 mmol/kg (39.5, 29.1, and 16.9%, respectively). In amended soils, there was no difference in sclerotial germination compared to non-amended soils, but in the greenhouse experiment there was a Trichoderma spp. population increase of over 300% in amended soil [3.4 × 106 colony forming units (CFU)/g soil] compared to the non-amended soil (9.6 × 105 CFU/g soil). Soil autoclaving had no effect on sclerotial germination at low VFA concentrations, but sclerotial germination was reduced at higher VFA concentrations compared to non-autoclaved soil. Our results suggest that VFAs contribute to sclerotial mortality in strongly acidic soil environments, and mortality is influenced by VFA components and environment. Antifungal activity is less for acetic acid than for n-butyric, and less in non-sterile soil environments more typical of field conditions than in sterile laboratory conditions.

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Volatile fatty acid concentration, soil pH and soil texture during anaerobic soil conditions affect viability of Athelia (Sclerotium) rolfsii sclerotia

et al. 2021

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Role of substrate decomposability and volatile fatty acids in anaerobic soil disinfestation activity against Sclerotinia sclerotiorum

Cited by 5 publications

References 31 publications

Amendment Properties Affect Crop Performance, Leaf Tissue Nitrogen, and Soil Nitrogen Availability Following Soil Treatment by Anaerobic Soil Disinfestation

Amendment Properties Affect Crop Performance, Leaf Tissue Nitrogen, and Soil Nitrogen Availability Following Soil Treatment by Anaerobic Soil Disinfestation

Mechanisms of Anaerobic Soil Disinfestation: Volatile Fatty Acids Reduce Viability of Athelia (Sclerotium) rolfsii Sclerotia in Acidic Soil Conditions and Have Limited Effects on Endemic Trichoderma spp.

Volatile fatty acid concentration, soil pH and soil texture during anaerobic soil conditions affect viability of Athelia (Sclerotium) rolfsii sclerotia

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