Carbon source dependent-anaerobic soil disinfestation (ASD) mitigates the sclerotial germination of Sclerotinia sclerotiorum

2020 ◽  
Vol 45 (1) ◽  
pp. 13-24 ◽  
Author(s):  
T. Mahalingam ◽  
C. S. K. Rajapakse ◽  
K. P. Somachandra ◽  
R. N. Attanayake
Keyword(s):  
Carbon Source ◽  
Sclerotinia Sclerotiorum ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Sclerotial Germination

scholarly journals Anaerobic Soil Disinfestation Reduces Viability of Sclerotinia sclerotiorum and S. minor Sclerotia and Root-Knot Nematodes in Muck Soils

2020 ◽  
Vol 110 (4) ◽  
pp. 795-804
Author(s):  
Andres D. Sanabria-Velazquez ◽  
Anna L. Testen ◽  
Ram B. Khadka ◽  
Zhe Liu ◽  
Fuqing Xu ◽  
...  
Keyword(s):  
Carbon Source ◽  
Sclerotinia Sclerotiorum ◽  
Wheat Bran ◽  
Carbon Sources ◽  
Ethanol Solution ◽  
Meloidogyne Hapla ◽  
Root Knot Nematodes ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Muck Soil

Experiments were conducted to evaluate potential functional and mechanistic differences in the suppression of Sclerotinia sclerotiorum and S. minor and root-knot nematodes in muck soils by anaerobic soil disinfestation (ASD) using different carbon source amendments. Volatile compounds produced during ASD in muck soil amended with molasses, wheat bran, or mustard greens at 20.2 Mg/ha or a 2% ethanol solution significantly reduced the mycelial growth and number of sclerotia produced by both Sclerotinia spp. compared with the anaerobic control. In amended soils, acetic and butyric acids were detected in concentrations that reduced the viability of sclerotia of both pathogens. Higher concentrations of carbon dioxide were observed in ASD-treated soils, regardless of the amendment, than in the nonamended anaerobic control. Only amendment with wheat bran did not increase the production of methane gas during ASD compared with the controls. Meloidogyne hapla survival was completely suppressed in soils treated with ASD regardless of carbon source. Field trials were conducted in Ohio muck soil to assess survival of sclerotia of both Sclerotinia spp. The viability of sclerotia of both Sclerotinia spp. was significantly reduced in soil subjected to ASD amended with wheat bran (20.2 Mg/ha), molasses (10.1 Mg/ha), or wheat bran (20.2 Mg/ha) plus molasses (10.1 Mg/ha) compared with the controls. A consistent negative correlation between soil reduction and viability of sclerotia of both pathogens was observed. Wheat bran and molasses are both widely available amendments that can be used as ASD carbon sources for the management of soilborne pathogens in muck soils.

scholarly journals Effects of Anaerobic Soil Disinfestation on Sclerotinia sclerotiorum in Paraguay

2019 ◽  
Vol 20 (1) ◽  
pp. 50-60
Author(s):  
Andres D. Sanabria-Velazquez ◽  
Anna L. Testen ◽  
Guillermo A. Enciso ◽  
Laura C. Soilan ◽  
Sally A. Miller
Keyword(s):  
Carbon Source ◽  
Sclerotinia Sclerotiorum ◽  
Wheat Bran ◽  
Carbon Sources ◽  
Significant Negative Correlation ◽  
Field Trials ◽  
Plastic Mulch ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Reducing Conditions

The effects of anaerobic soil disinfestation (ASD) on Sclerotinia sclerotiorum sclerotia viability was tested in four field trials in Paraguay. Plots were amended with wheat bran (20.2 Mg/ha), molasses (10.1 Mg/ha), or wheat bran (20.2 Mg/ha) plus molasses (10.1 Mg/ha), saturated with water, and covered with black plastic mulch for 3 weeks. Control plots were not amended but were saturated and either covered (anaerobic control) or maintained uncovered (aerobic control). Tubes painted with iron oxide paint were placed in soils to assess soil reducing conditions. Sclerotia were buried 6 cm deep in treated and control soils along with temperature data loggers. After 3 weeks, the viability of sclerotia was significantly lower in all ASD-treated soils (4 to 52%) compared with the aerobic control soil (100%), regardless of the carbon source used. Sclerotial viability was also significantly reduced compared with anaerobic controls at three sites, depending on the carbon source used. A significant negative correlation between soil reducing conditions and sclerotia viability was observed at all sites. Wheat bran and molasses are widely available and inexpensive in Paraguay, and ASD with these carbon sources provides smallholder South American vegetable farmers with a new option for sustainable management of Sclerotinia and potentially other soilborne pathogens.

scholarly journals Carbon Source and Soil Origin Shape Soil Microbiomes and Tomato Soilborne Pathogen Populations During Anaerobic Soil Disinfestation

2018 ◽  
Vol 2 (3) ◽  
pp. 138-150 ◽  
Author(s):  
Anna L. Testen ◽  
Sally A. Miller
Keyword(s):  
Carbon Source ◽  
Wheat Bran ◽  
Root Rot ◽  
Bacterial Communities ◽  
Soilborne Diseases ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Soil Bacterial Communities ◽  
Soil Origin ◽  
Soil Bacterial

Soilborne disease complexes are an emerging constraint in protected culture tomato production systems in the Midwestern United States. Diseases in these complexes include Verticillium wilt (Verticillium dahliae), black dot root rot (Colletotrichum coccodes), corky root rot (Pyrenochaeta lycopersici), and root knot (Meloidogyne spp.). Anaerobic soil disinfestation (ASD) may be a viable, environmentally benign strategy for managing these complexes. Soils from two farms in Ohio were used to determine the impacts of ASD, using wheat bran, molasses, or ethanol as carbon sources, on soilborne diseases and soil bacterial communities. ASD with wheat bran or ethanol amendments led to significantly reduced tomato root rot severity, while nematode galling damage was significantly reduced following ASD with any carbon source compared with nontreated controls. When ethanol was used as a carbon source in ASD, the colonization of tomato roots by P. lycopersici and C. coccodes was observed less frequently than in control roots. A high throughput sequencing approach was used to characterize soil bacterial communities following ASD. Carbon source and soil origin influenced the composition of bacterial communities in soils treated with ASD. Bacterial community diversity decreased following ASD with wheat bran in all soils tested and following ASD with ethanol in soils from one farm. The abundance of bacteria in the phylum Firmicutes generally increased significantly following ASD, while the abundance of those in the phyla Acidobacteria, Actinobacteria, Chloroflexi, and Plantomycetes generally decreased following ASD. These findings provide insight into the impacts of ASD on microbial communities and soilborne diseases and will be used to optimize ASD as a tool for Midwestern vegetable growers.

scholarly journals 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.

2021 ◽  
Vol 5 ◽  
Author(s):  
Keagan J. Swilling ◽  
Utsala Shrestha ◽  
Bonnie H. Ownley ◽  
Kimberly D. Gwinn ◽  
David M. Butler
Keyword(s):  
Fatty Acids ◽  
Butyric Acid ◽  
Plant Pathogen ◽  
Volatile Fatty Acids ◽  
Sclerotium Rolfsii ◽  
Acidic Soil ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Soil Exposure ◽  
Sclerotial Germination

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.

scholarly journals Synergy of Anaerobic Soil Disinfestation and Trichoderma spp. in Rhizoctonia Root Rot Suppression

2021 ◽  
Vol 5 ◽  
Author(s):  
Ram B. Khadka ◽  
Sally A. Miller
Keyword(s):  
Carbon Source ◽  
Rhizoctonia Solani ◽  
Wheat Bran ◽  
Root Rot ◽  
Carbon Sources ◽  
Chicken Manure ◽  
Treated Soil ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Rhizoctonia Root Rot

Potential synergy between anaerobic soil disinfestation (ASD) and Trichoderma spp. in suppression of Rhizoctonia root rot in radish was evaluated. A split-plot design with three replications was used; main plots were Trichoderma harzianum T22, Trichoderma asperellum NT25 and a non-Trichoderma control. Subplots were ASD carbon sources wheat bran, molasses, chicken manure, and mustard greens and two non-amended controls: anaerobic (covered and flooded) and aerobic (not covered or flooded). Carbon sources and Rhizoctonia solani inoculant were mixed with soil, placed in pots, and flooded, followed by drenching Trichoderma spore suspensions and sealing the pots in zip-lock bags. After 3 weeks, bags were removed, soil was aired for 1 week and radish “SSR-RR-27” was seeded. Rhizoctonia root rot severity and incidence were lowest in radish plants grown in ASD-treated soil amended with wheat bran, molasses, or mustard greens across all Trichoderma treatments. Disease severity was lower in radish plants treated with NT25 than with T22 or the non-Trichoderma control across all ASD treatments, and in radish grown in ASD-treated soil amended with wheat bran plus NT25 compared to ASD-wheat bran or NT25 alone. Rhizoctonia solani populations were significantly reduced by ASD treatment regardless of carbon source, while Trichoderma populations were not affected by ASD treatment with the exception of ASD-mustard greens. The interactions of either Trichoderma isolate and ASD with most carbon sources were additive, while T22 with ASD-molasses and NT25 with ASD–wheat bran interactions were synergistic in reducing disease severity. One interaction, T22 with ASD-chicken manure was antagonistic. Enhancement of ASD efficacy in suppressing soilborne diseases such as Rhizoctonia root rot by additional soil amendment with Trichoderma spp. during the process appears to be dependent on both Trichoderma isolate and ASD carbon source.

scholarly journals Carbon Source-Dependent Effects of Anaerobic Soil Disinfestation on Soil Microbiome and Suppression of Rhizoctonia solani AG-5 and Pratylenchus penetrans

2016 ◽  
Vol 106 (9) ◽  
pp. 1015-1028 ◽  
Author(s):  
Shashika S. Hewavitharana ◽  
Mark Mazzola
Keyword(s):  
Carbon Source ◽  
Rhizoctonia Solani ◽  
Application Rate ◽  
Disease Suppression ◽  
Soil Microbiome ◽  
Pratylenchus Penetrans ◽  
Root Infection ◽  
Soil Suppressiveness ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation

The effect of carbon source on efficacy of anaerobic soil disinfestation (ASD) toward suppression of apple root infection by Rhizoctonia solani AG-5 and Pratylenchus penetrans was examined. Orchard grass (GR), rice bran (RB), ethanol (ET), composted steer manure (CM), and Brassica juncea seed meal (SM) were used as ASD carbon inputs, with plant assays conducted in natural and pasteurized orchard soils. Subsequent studies investigated the effect of GR application rate used in ASD on control of these pathogens. In general, apple root infection by R. solani AG-5 was significantly lower in ET, GR, RB, and SM ASD treatments compared with the control. Among different ASD treatments, apple seedling growth was significantly greater when GR or SM was used as the carbon input relative to all other ASD treatments. R. solani AG-5 DNA abundance was significantly reduced in all ASD treatments, regardless of amendment type, compared with the control. In independent experiments, ASD-GR was consistently superior to ASD-CM for limiting pathogen activity in soils. ASD treatment with a grass input rate of 20 t ha−1 provided superior suppression of P. penetrans but grass application rate did not affect ASD efficacy in control of R. solani AG-5. The soil microbiome from ASD-GR-treated soils was clearly distinct from the control and ASD-CM-treated soils. In contrast, composition of the microbiome from control and ASD-CM-treated soils could not be differentiated. Comparative results from pasteurized and nonpasteurized soils suggest that there is potential for GR based ASD treatment to recruit microbial elements that persist over the anaerobic phase of soil incubation, which may functionally contribute to disease suppression. When ASD was conducted with GR, microbial diversity was markedly reduced relative to the control or ASD-CM soil suggesting that this parameter, typically associated with system resilience, was not instrumental to the function of ASD-induced soil suppressiveness.

scholarly journals Anaerobic Soil Disinfestation Reduces Germination and Affects Colonization of Sclerotium rolfsii Sclerotia

2018 ◽  
Vol 108 (3) ◽  
pp. 342-351 ◽  
Author(s):  
Utsala Shrestha ◽  
Mary E. Dee ◽  
Bonnie H. Ownley ◽  
David M. Butler
Keyword(s):  
Field Study ◽  
C:N Ratio ◽  
Sclerotium Rolfsii ◽  
Field Studies ◽  
Growth Chamber ◽  
Fusarium Spp ◽  
Trichoderma Spp ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Sclerotial Germination

Growth chamber and field studies were conducted with organic amendment mixtures of carbon (C) and nitrogen (N) at C:N ratios 10:1, 20:1, 30:1, and 40:1 and amendment rates of C at 2, 4, 6, and 8 mg/g of soil (C:N ratio 30:1) to evaluate anaerobic soil disinfestation (ASD) effects on germination and colonization of Sclerotium rolfsii. In the growth chamber, sclerotial germination was reduced in all ASD treatments regardless of C:N ratio (0.6 to 8.5% germination) or amendment rate (7.5 to 46%) as compared with nonamended controls (21 to 36% and 61 to 96%, respectively). ASD treatment increased Trichoderma spp. colonization of sclerotia, with consistently higher colonization in ASD treatments with amendment rates of C at 2 or 4 mg/g of soil (>87% colonization) compared with nonamended controls (<50% colonization). In the 2014 field study, sclerotial germination was reduced by 24 to 30% in ASD treatments when compared with the nonamended control. Sclerotial colonization by Trichoderma spp. was predominant; however, other potential mycoparasites (i.e., Aspergillus spp., Fusarium spp., zygomycetes, and other fungi) were present in the field study. Amendment C:N ratios in the range of 10:1 to 40:1 were equally effective in reducing sclerotial germination and enhancing colonization by potentially beneficial mycoparasites of sclerotia.

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