Articles
Survival and fungal colonization of the tomato pathogen Athelia rolfsii (syn. Sclerotium rolfsii) in response to organic soil health practices
Article number
1445_8
Pages
51 – 58
Language
English
Abstract
Organic soil fertility practices, such as compost amendment and cover cropping, are linked to numerous soil health benefits, including greater microbial biomass and activity.
Less is known about how organic management influences persistence of plant pathogenic fungi in soil.
Southern blight is one of the most destructive diseases in processing tomato worldwide.
The causal agent, Athelia rolfsii (syn. Sclerotium rolfsii), can persist in soil for several years by producing durable masses of fungal tissue, called sclerotia.
To test the hypothesis that organic soil management practices can suppress A. rolfsii populations, we investigated the impact of long-term organic versus conventional soil fertility regimes on survival of A. rolfsii sclerotia.
We also identified biological indicators of pathogen suppressive soil based on fungal communities within sclerotia (potential mycoparasites). In greenhouse pot studies, we buried sclerotia in soil that was collected from processing tomato-corn rotation plots with either conventional (synthetic fertilizer) or organic (compost and cover cropping) fertility regimes for over 25 years.
After one month, sclerotia were less decomposed in organic soil; however, adding chitin to soil counteracted this negative effect.
Fungal genera most commonly isolated from nonviable sclerotia in culture-based assays were Sarocladium, Aspergillus, Cladosporium, Fusarium, and Corallomycetella. In a field experiment, sclerotia were buried for three months in organic and conventional plots.
Amplicon sequencing-based metagenomic analysis revealed unique fungal colonizer community profiles in sclerotia that were buried in different soils, indicating a biological basis for the impact of soil fertility practices on pathogen survival.
Based on differential abundance analysis, fungal genera Sarocladium, Trichoderma, Penicillium, Cladosporium, Chaetomium, and Botryotrichum most extensively colonized sclerotia, with higher relative abundance of Trichoderma and lower abundance of Botryotrichum in sclerotia buried in conventional versus organic plots.
Organic practices altered microbial colonization of pathogen survival structures, which has significant implications for soilborne pathogen management.
Less is known about how organic management influences persistence of plant pathogenic fungi in soil.
Southern blight is one of the most destructive diseases in processing tomato worldwide.
The causal agent, Athelia rolfsii (syn. Sclerotium rolfsii), can persist in soil for several years by producing durable masses of fungal tissue, called sclerotia.
To test the hypothesis that organic soil management practices can suppress A. rolfsii populations, we investigated the impact of long-term organic versus conventional soil fertility regimes on survival of A. rolfsii sclerotia.
We also identified biological indicators of pathogen suppressive soil based on fungal communities within sclerotia (potential mycoparasites). In greenhouse pot studies, we buried sclerotia in soil that was collected from processing tomato-corn rotation plots with either conventional (synthetic fertilizer) or organic (compost and cover cropping) fertility regimes for over 25 years.
After one month, sclerotia were less decomposed in organic soil; however, adding chitin to soil counteracted this negative effect.
Fungal genera most commonly isolated from nonviable sclerotia in culture-based assays were Sarocladium, Aspergillus, Cladosporium, Fusarium, and Corallomycetella. In a field experiment, sclerotia were buried for three months in organic and conventional plots.
Amplicon sequencing-based metagenomic analysis revealed unique fungal colonizer community profiles in sclerotia that were buried in different soils, indicating a biological basis for the impact of soil fertility practices on pathogen survival.
Based on differential abundance analysis, fungal genera Sarocladium, Trichoderma, Penicillium, Cladosporium, Chaetomium, and Botryotrichum most extensively colonized sclerotia, with higher relative abundance of Trichoderma and lower abundance of Botryotrichum in sclerotia buried in conventional versus organic plots.
Organic practices altered microbial colonization of pathogen survival structures, which has significant implications for soilborne pathogen management.
Authors
K.R. Paugh, A.T. Poret-Peterson, C.L. Swett
Keywords
disease, pathogen, crop protection, organic, compost, cover cropping, southern blight, sclerotia, microbiome, soil health
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