SUPPRESSION OF SOILBORNE FUNGAL DISEASES WITH ORGANIC AMENDMENTS (original) (raw)
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Suppression of soilborne fungal diseases with organic amendments. J Plant Pathol
The use of organic matter (OM) has been proposed, for both conventional and biological agriculture systems, to decrease the incidence of plant diseases caused by soilborne pathogens. In this work we review reports on the application of OM amendments, focusing on the suppressive capacity of different OM materials and the response of different soilborne pathogens. A total of 250 articles were analysed, with 2423 experimental case studies. The effect of OM amendments was found to be suppressive in 45% and non-significant in 35% of the cases. In 20% of the cases, a significant increase of disease incidence was observed. Compost was the most suppressive material, with more than 50% of cases showing effective disease control. The effect of crop residues was more variable: it was suppressive in 45% of the cases, but enhanced disease in 28%. Finally, significant disease suppression with peat was recorded only in 4% of the experiments. The ability of OM to suppress disease varied largely with different pathogens: it was observed in more than 50% of the cases for Verticillium, Thielaviopsis, Fusarium and Phytophthora. In contrast, effective control of Rhizoctonia solani was achieved only in 26% of the cases. From this review it emerged that OM amendments have great potential but, at the same time, present some inconsistencies in their application. More investigation on the mechanisms by which OM acts on disease suppression is needed to make the use of these materials more predictable.
Identifying the characteristics of organic soil amendments that suppress soilborne plant diseases
Soil Biology & Biochemistry, 2010
Application of organic amendments has been proposed as a strategy for the management of diseases caused by soilborne pathogens. However, inconsistent results seriously hinder their practical use. In this work we use an extensive data set of 2423 studies derived from 252 papers to explore this strategy. First, we assess the capability of a specific organic amendment to control different diseases; second, we investigate the influence of organic matter (OM) decomposition on disease suppressiveness; and third, we search for physical, chemical and biological parameters able to identify suppressive OM. OM was found to be consistently suppressive to different pathogens in only a few studies where a limited number of pathogens were tested. In the majority of studies a material suppressive to a pathogen was ineffective or even conducive to other pathogens, suggesting that OM suppressiveness is often pathogen-specific. OM decomposition in many studies (73%, n ¼ 426) emerged as a crucial process affecting suppressiveness. During decomposition, disease suppression either increased, decreased, was unchanged or showed more complex responses, such as 'hump-shaped' dynamics. Peat suppressiveness generally decreased during decomposition, while responses of composts and crop residues were more complex. However, due to the many interactions of contributing factors (OM quality, microbial community composition, pathosystem tested and decomposition time), it was difficult to identify specific predictors of disease suppression. Among the 81 parameters analysed, only some of the 643 correlations showed a consistent relationship with disease suppression. The response of pathogen populations to OM amendments was a reliable feature only for some organic matter types (e.g. crop residues and organic wastes with C-to-N ratio lower than w15) and for pathogens with a limited saprophytic ability (e.g., Thielaviopsis basicola and Verticillium dahliae). Instead, population responses of the pathogenic fungi Phytophthora spp., Rhizoctonia solani and Pythium spp. appeared unrelated to disease suppression. Overall, enzymatic and microbiological parameters, rather than chemical ones, were much more informative for predicting suppressiveness. The most useful features were FDA activity, substrate respiration, microbial biomass, total culturable bacteria, fluorescent pseudomonads and Trichoderma populations. We conclude that the integration of different parameters (e.g. FDA hydrolysis and chemical composition by 13 C NMR) may be a promising approach for identification of suppressive amendments.
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2001
The utilization of organic amendments for control of soil-borne plant pathogens has often been considered at best variable, but more often as a snake-oil remedy. Understanding the mode of action of these products, however, provides insight as to where and how to exploit these underutilized energy sources for the benefit of plant and soil health. Organic amendments containing high nitrogen, such as poultry manure, meat and bone meal, and soymeal, significantly reduced populations of a wide spectrum of soil-borne plant pathogens. Pathogen control was shown to arise from the ammonia and (or) nitrous acid generated, the concentrations of which are controlled by pH, organic matter content, soil buffering capacity, and nitrification rate. Swine manure can reduce pathogen populations by both these mechanisms as well as by an additional process involving volatile fatty acids. Volatile fatty acids are active only at pH conditions below 6.0 and were present in most, but not all liquid manures tested. Disease control with organic amendment occurs when soil and biological factors are conducive to activating the processes that reduce pathogen survival. Understanding the mechanisms allows prediction of efficacy based on analysis of the soil and the organic amendment. For some products, such as ammonium lignosulfonate, a by-product of the pulp and paper industry, disease control was demonstrated but the mode of action is as yet unclear. Although organic amendments reduce populations of plant pathogens, overall they lead to an increase in soil microorganisms populations by up to 1000-fold following application. Thus, the displacement of pathogens is selective and can persist in fields for several years after single application. As we unravel the potential benefits of organic treatments, there is indication that they may return as a valuable tool in disease management strategies. Résumé : L'emploi d'amendements organiques pour la lutte aux agents phytopathogènes du sol a souvent été considéré d'une efficacité incertaine dans les meilleurs des cas et, encore plus souvent, comme un remède de charlatan. Cependant, la compréhension du mode d'action de ces produits nous permet de savoir où et comment utiliser ces sources d'énergie sous-exploitées au bénéfice de la santé des plantes et des sols. Des amendements organiques à teneur élevée en azote tels que le fumier de volaille, la farine de viande et d'os et le tourteau de soja réduisent significativement les populations d'une multitude d'agents phytopathogènes du sol. Il a été démontré que l'activité contre les agents pathogènes est due à l'ammoniac ou l'acide nitreux générés, dont les concentrations sont contrôlées par le pH, la teneur en matière organique, le pouvoir tampon du sol et le taux de nitrification. Le fumier de porc peut réduire les populations d'agents pathogènes par ces deux mécanismes aussi bien que par des processus supplémentaires impliquant des acides gras volatils. Les acides gras volatiles sont actifs seulement dans des conditions de pH inférieur à 6,0 et étaient présents dans presque tous les purins testés. La lutte aux maladies par les amendements organiques se produit lorsque les facteurs édaphiques et biologiques contribuent à l'activation des processus qui diminuent la survie des agents pathogènes. La compréhension de ces mécanismes permet de prédire l'efficacité après l'analyse du sol et des amendements organiques. Pour certains produits, comme le lignosulfate d'ammonium, un sous-produit de l'industrie des pâtes et papier, l'efficacité de la lutte aux maladies a été démontrée bien que le mode d'action demeure inconnu. Alors que les amendements organiques réduisent les populations d'agents phytopathogènes, en général, ils induisent une augmentation des populations des microorganismes du sol par un facteur de 1000, suite à l'application. Donc, il y a déplacement sélectif des agents pathogènes, lequel peut persister plusieurs années en champ après une seule application. Alors que nous découvrons les bénéfices potentiels des traitements organiques, il y a des indications que Can.
Suppressing soil-borne diseases with residue management and organic amendments
Soil and Tillage Research, 2003
Changes in agricultural practices with time have led to a decline in soil structure and with it, an increase in soil-borne plant diseases. Agricultural practices such as incorporating organic amendments and managing the type and quantity of crop residue, have a direct impact on plant health and crop productivity. Soil management practices involving tillage, rotation, and burning will impact the amount and quality of organic matter that is returned to the soil. These practices influence pathogen viability and distribution, nutrient availability, and the release of biologically active substances from both crop residues and soil microorganisms as illustrated by the model system of Cochliobolus sativus on the development of common root rot in cereals. The application of organic amendments, manures and composts that are rich in nitrogen, may reduce soil-borne diseases by releasing allelochemicals generated during product storage or by subsequent microbial decomposition. The modes of action for disease suppression are elucidated for a number of diseases including verticillium wilt and common scab of potato. Developing disease suppressive soils by introducing organic amendments and crop residue management takes time, but the benefits accumulate across successive years improving soil health and structure. Crown
Fungi play an essential role in recovering the quality and fertility of soil. There is a limited understating of the complex response of fungal diversity to different organic materials in clay loam soil. Here, we report the response of soil fungi toward the short-term application of manure (M), sugarcane straw (S), and sugarcane straw plus manure (MS), including no organic material control (CK) at two different time points (50 and 100 days after application). Illumina sequencing was used to examine the fungal communities. Our results reveal a significant shift among the soil fungal community structure associated with each organic material application. After both time points, amendments-especially M and MS-decreased the fungal richness and stimulated the copiotrophic fungal group (Ascomycota) compared to the control soil (CK) and S-amended soil. On the contrary, as compared to the M and MS-amended soils, the CK and S-amended soils at both time points increased the fungal richness and stimulated the oligotrophic fungal groups. Organic material use, especially M and MS, showed variable results regarding pathogenic fungi enhancing the abundance of Lophodermium and Cercophora and decreasing Fusarium. Concerning the abundance of plant-beneficial fungi, Mortierella was reduced, and Podospora was increased by M and MS input. FUNGuild showed that the amendment of organic materials efficiently declined the abundance of endophytes and plant pathogens, but also enhanced the animal pathogens in terms of abundance with respect to CK at two time points. This study could be useful to provide a novel understanding of the management of soil-borne pathogens by organic amendments for the sustainable production of short-term crops.
Review Enhancing Soil Quality and Plant Health Through Suppressive Organic Amendments
2012
The practice of adding organic amendments to crop soils is undergoing resurgence as an efficient way to restore soil organic matter content and to improve soil quality. The quantity and quality of the organic matter inputs affect soil physicochemical properties and soil microbiota, influencing different parameters such as microbial biomass and diversity, community structure and microbial activities or functions. The influence of organic amendments on soil quality has also effects on crop production and plant health. The enhancement of soil suppressiveness using organic amendments has been widely described, especially for soil-borne diseases. However, there is great variability in the effectiveness of suppression depending on the nature of the amendment, the crop, the pathogen, and the environmental conditions. Although the effects of organic amendments on soil properties have been widely studied, relationships between these properties and soil suppressiveness are not still well understood. Changes in soil physicochemical parameters may modulate the efficacy of suppression. However, the parameters more frequently associated to disease suppression appear to be related to soil microbiota, such as microbial biomass and activity, the abundance of specific microbial groups and some hydrolytic activities. This review focuses on the effect of organic amendments on soil microbial populations, diversity and activities; their ability to enhance plant health through disease suppression; and which of the parameters affected by the organic amendments are potentially involved in soil suppressiveness.
Control of Soilborne Plant Pathogens by Incorporating Fresh Organic Amendments Followed by Tarping
Phytopathology, 2000
A new method for the control of soilborne plant pathogens was tested for its efficacy in two field experiments during two years. Plots were amended with fresh broccoli or grass (3.4 to 4.0 kg fresh weight m-2) or left nonamended, and covered with an airtight plastic cover (0.135 mm thick) or left noncovered. In plots amended with broccoli or grass and covered with plastic sheeting, anaerobic and strongly reducing soil conditions developed quickly, as indicated by rapid depletion of oxygen and a decrease in redox potential values to as low as -200 mV. After 15 weeks, survival of Fusarium oxysporum f. sp. asparagi, Rhizoctonia solani, and Verticillium dahliae in inoculum samples buried 15 cm deep was strongly reduced in amended, covered plots in both experiments. The pathogens were not or hardly inactivated in amended, noncovered soil or nonamended, covered soil. The latter indicates that thermal inactivation due to increased soil temperatures under the plastic cover was not involved ...
Frontiers in Plant Science, 2021
Agriculture is faced with many challenges including loss of biodiversity, chemical contamination of soils, and plant pests and diseases, all of which can directly compromise plant productivity and health. In addition, inadequate agricultural practices which characterize conventional farming play a contributory role in the disruption of the plant-microbe and soil-plant interactions. This review discusses the role of organic amendments in the restoration of soil health and plant disease management. While the use of organic amendments in agriculture is not new, there is a lack of knowledge regarding its safe and proper deployment. Hence, a biorational approach of organic amendment use to achieve sustainable agricultural practices entails the deployment of botanicals, microbial pesticides, and organic minerals as organic amendments for attaining plant fitness and disease suppression. Here, the focus is on the rhizosphere microbial communities. The role of organic amendments in stimulati...
Enhancing Soil Quality and Plant Health Through Suppressive Organic Amendments
Diversity, 2012
The practice of adding organic amendments to crop soils is undergoing resurgence as an efficient way to restore soil organic matter content and to improve soil quality. The quantity and quality of the organic matter inputs affect soil physicochemical properties and soil microbiota, influencing different parameters such as microbial biomass and diversity, community structure and microbial activities or functions. The influence of organic amendments on soil quality has also effects on crop production and plant health. The enhancement of soil suppressiveness using organic amendments has been widely described, especially for soil-borne diseases. However, there is great variability in the effectiveness of suppression depending on the nature of the amendment, the crop, the pathogen, and the environmental conditions. Although the effects of organic amendments on soil properties have been widely studied, relationships between these properties and soil suppressiveness are not still well understood. Changes in soil physicochemical parameters may modulate the efficacy of suppression. However, the parameters more frequently associated to disease suppression appear to be related to soil microbiota, such as microbial biomass and activity, the abundance of specific microbial groups and some hydrolytic activities. This review focuses on the effect of organic amendments on soil microbial populations, diversity and activities; their ability to enhance plant health through disease suppression; and which of the parameters affected by the organic amendments are potentially involved in soil suppressiveness.