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Reducing the Use of Pesticides with Site-Specific Application: The Chemical Control of Rhizoctonia solani as a Case of Study for the Management of Soil-Borne Diseases

View Article: PubMed Central - PubMed

ABSTRACT

Reducing our reliance on pesticides is an essential step towards the sustainability of agricultural production. One approach involves the rational use of pesticides combined with innovative crop management. Most control strategies currently focus on the temporal aspect of epidemics, e.g. determining the optimal date for spraying, regardless of the spatial mechanics and ecology of disease spread. Designing innovative pest management strategies incorporating the spatial aspect of epidemics involves thorough knowledge on how disease control affects the life-history traits of the pathogen. In this study, using Rhizoctonia solani/Raphanus sativus as an example of a soil-borne pathosystem, we investigated the effects of a chemical control currently used by growers, Monceren® L, on key epidemiological components (saprotrophic spread and infectivity). We tested the potential “shield effect” of Monceren® L on pathogenic spread in a site-specific application context, i.e. the efficiency of this chemical to contain the spread of the fungus from an infected host when application is spatially localized, in our case, a strip placed between the infected host and a recipient bait. Our results showed that Monceren® L mainly inhibits the saprotrophic spread of the fungus in soil and may prevent the fungus from reaching its host plant. However, perhaps surprisingly we did not detect any significant effect of the fungicide on the pathogen infectivity. Finally, highly localized application of the fungicide—a narrow strip of soil (12.5 mm wide) sprayed with Monceren® L—significantly decreased local transmission of the pathogen, suggesting lowered risk of occurrence of invasive epidemics. Our results highlight that detailed knowledge on epidemiological processes could contribute to the design of innovative management strategies based on precision agriculture tools to improve the efficacy of disease control and reduce pesticide use.

No MeSH data available.


Saprozone dynamics for saprotrophic spread of Rhizoctonia solani, describing the change in the probability colonization for a bait placed at a given distance from a mycelium disc and after a given time of exposure.Circles indicate data observed in the placement experiments.
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pone.0163221.g003: Saprozone dynamics for saprotrophic spread of Rhizoctonia solani, describing the change in the probability colonization for a bait placed at a given distance from a mycelium disc and after a given time of exposure.Circles indicate data observed in the placement experiments.

Mentions: Although some parameters were difficult to estimate (Table 1 and Fig 2), the saprozone model (A1) captured the general overall pattern of the data (Fig 3 and S1 File), allowing us to analyse the effects of fungicide application—the main aim of this experiment. While the statistical inference provided relatively satisfactory estimations with narrow posterior distributions for the water treatment, the fit of the model to the fungicide treatment data showed higher uncertainty in the Bayesian estimation of parameters (wider posterior distributions). The comparison between treatments corroborates our empirical analysis and provided a better visualization and mechanistic understanding of the effect of the fungicide on mycelial spread through soil. Our results suggest that the fungicide most affected the rate of spatial decline (σ1) and thus, the ability of the fungus to develop its mycelial network in space from a primary propagule (i.e. from the mycelium disc). The estimated median of the spatial decline parameter (σ1) in the water treatment (control) was 25 times higher in the Monceren® L treatment (0.002 and 0.049 mm², respectively; Table 1). The observed local discrepancies of model fitting and the uncertainty in parameter estimation for the fungicide treatment may be due to the lack of information at critical points of the saprozone profiles, and/or to the need to relax and modify some assumptions of the model.


Reducing the Use of Pesticides with Site-Specific Application: The Chemical Control of Rhizoctonia solani as a Case of Study for the Management of Soil-Borne Diseases
Saprozone dynamics for saprotrophic spread of Rhizoctonia solani, describing the change in the probability colonization for a bait placed at a given distance from a mycelium disc and after a given time of exposure.Circles indicate data observed in the placement experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036793&req=5

pone.0163221.g003: Saprozone dynamics for saprotrophic spread of Rhizoctonia solani, describing the change in the probability colonization for a bait placed at a given distance from a mycelium disc and after a given time of exposure.Circles indicate data observed in the placement experiments.
Mentions: Although some parameters were difficult to estimate (Table 1 and Fig 2), the saprozone model (A1) captured the general overall pattern of the data (Fig 3 and S1 File), allowing us to analyse the effects of fungicide application—the main aim of this experiment. While the statistical inference provided relatively satisfactory estimations with narrow posterior distributions for the water treatment, the fit of the model to the fungicide treatment data showed higher uncertainty in the Bayesian estimation of parameters (wider posterior distributions). The comparison between treatments corroborates our empirical analysis and provided a better visualization and mechanistic understanding of the effect of the fungicide on mycelial spread through soil. Our results suggest that the fungicide most affected the rate of spatial decline (σ1) and thus, the ability of the fungus to develop its mycelial network in space from a primary propagule (i.e. from the mycelium disc). The estimated median of the spatial decline parameter (σ1) in the water treatment (control) was 25 times higher in the Monceren® L treatment (0.002 and 0.049 mm², respectively; Table 1). The observed local discrepancies of model fitting and the uncertainty in parameter estimation for the fungicide treatment may be due to the lack of information at critical points of the saprozone profiles, and/or to the need to relax and modify some assumptions of the model.

View Article: PubMed Central - PubMed

ABSTRACT

Reducing our reliance on pesticides is an essential step towards the sustainability of agricultural production. One approach involves the rational use of pesticides combined with innovative crop management. Most control strategies currently focus on the temporal aspect of epidemics, e.g. determining the optimal date for spraying, regardless of the spatial mechanics and ecology of disease spread. Designing innovative pest management strategies incorporating the spatial aspect of epidemics involves thorough knowledge on how disease control affects the life-history traits of the pathogen. In this study, using Rhizoctonia solani/Raphanus sativus as an example of a soil-borne pathosystem, we investigated the effects of a chemical control currently used by growers, Monceren® L, on key epidemiological components (saprotrophic spread and infectivity). We tested the potential “shield effect” of Monceren® L on pathogenic spread in a site-specific application context, i.e. the efficiency of this chemical to contain the spread of the fungus from an infected host when application is spatially localized, in our case, a strip placed between the infected host and a recipient bait. Our results showed that Monceren® L mainly inhibits the saprotrophic spread of the fungus in soil and may prevent the fungus from reaching its host plant. However, perhaps surprisingly we did not detect any significant effect of the fungicide on the pathogen infectivity. Finally, highly localized application of the fungicide—a narrow strip of soil (12.5 mm wide) sprayed with Monceren® L—significantly decreased local transmission of the pathogen, suggesting lowered risk of occurrence of invasive epidemics. Our results highlight that detailed knowledge on epidemiological processes could contribute to the design of innovative management strategies based on precision agriculture tools to improve the efficacy of disease control and reduce pesticide use.

No MeSH data available.