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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.


Proportion of recipient baits colonized by Rhizoctonia solani upon saprotrophic spread at (A) 10 mm, (B) 12.5 mm and (C) 25 mm after treatment with Monceren® L (pink lines) or tap water (blue lines).Different letters indicate significant differences in the proportion of colonized baits (P-value < 0.05, Wald test).
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pone.0163221.g001: Proportion of recipient baits colonized by Rhizoctonia solani upon saprotrophic spread at (A) 10 mm, (B) 12.5 mm and (C) 25 mm after treatment with Monceren® L (pink lines) or tap water (blue lines).Different letters indicate significant differences in the proportion of colonized baits (P-value < 0.05, Wald test).

Mentions: In the absence of fungicide, the fungus was able to quickly colonize the surrounding soil surface. As shown in Fig 1A, 25% of recipient baits placed 10 mm away from the mycelium disc were colonized within 2 days after inoculation and a large proportion (75%) of recipient baits were colonized after 16 days. However, without a large source of nutrients (e.g. host), saprotrophic spread was spatially limited and declined abruptly with distance. At the end of the experiment, 54% of baits were colonized at 12.5 mm (Fig 1B) and only 7% at a distance of 25 mm (Fig 1C). The Monceren® L treatment radically altered colonization profiles (Fig 1). Fungicide treatment restricted saprotrophic mycelial growth to a smaller perimeter and colonization did not exceed 12.5 mm. Furthermore, the probability of saprotrophic spread was lower than that observed with the tap water control. There were significant differences between colonization profiles with or without fungicide only at short distances (10 mm, p<0.001, and 12.5 mm, p<0.001).


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
Proportion of recipient baits colonized by Rhizoctonia solani upon saprotrophic spread at (A) 10 mm, (B) 12.5 mm and (C) 25 mm after treatment with Monceren® L (pink lines) or tap water (blue lines).Different letters indicate significant differences in the proportion of colonized baits (P-value < 0.05, Wald test).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0163221.g001: Proportion of recipient baits colonized by Rhizoctonia solani upon saprotrophic spread at (A) 10 mm, (B) 12.5 mm and (C) 25 mm after treatment with Monceren® L (pink lines) or tap water (blue lines).Different letters indicate significant differences in the proportion of colonized baits (P-value < 0.05, Wald test).
Mentions: In the absence of fungicide, the fungus was able to quickly colonize the surrounding soil surface. As shown in Fig 1A, 25% of recipient baits placed 10 mm away from the mycelium disc were colonized within 2 days after inoculation and a large proportion (75%) of recipient baits were colonized after 16 days. However, without a large source of nutrients (e.g. host), saprotrophic spread was spatially limited and declined abruptly with distance. At the end of the experiment, 54% of baits were colonized at 12.5 mm (Fig 1B) and only 7% at a distance of 25 mm (Fig 1C). The Monceren® L treatment radically altered colonization profiles (Fig 1). Fungicide treatment restricted saprotrophic mycelial growth to a smaller perimeter and colonization did not exceed 12.5 mm. Furthermore, the probability of saprotrophic spread was lower than that observed with the tap water control. There were significant differences between colonization profiles with or without fungicide only at short distances (10 mm, p<0.001, and 12.5 mm, p<0.001).

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&reg; L, on key epidemiological components (saprotrophic spread and infectivity). We tested the potential &ldquo;shield effect&rdquo; of Monceren&reg; 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&reg; 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&mdash;a narrow strip of soil (12.5 mm wide) sprayed with Monceren&reg; L&mdash;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.