Rhizobacteria has shown promising results in managing nematodes and improving the root system of banana plants. However, their effects on commercial banana plants in different generations remain ...unclear. In this study performed under field experiment, we evaluated the effect of three types (injection, edaphic and foliar) of a local rhizobacterial consortium application on the system root, nematode populations, and their damage in the third-generation plants. Only mother and daughter plants were treated twice with the rhizobacteria. Plants not treated with rhizobacteria constituted the control treatment. Our results show that rhizobacteria affect different underground tissues and nematodes in third-generation banana plants. Helicotylenchus spp., Meloidogyne spp., Pratylenchus spp., Radopholus similis, and Rhabditis spp. were the nematodes found in banana roots. R. similis population and the damage in the root system of banana plants were reduced significantly by the rhizobacteria edaphic application. The application of rhizobacteria could be a sustainable management strategy over time to improve the root system and suppress nematodes, and their damage in commercial banana plants.
Phytophthora capsici is an oomycete that causes various symptoms, such as root, neck, stem, fruit rot, and leaf blight, in different plant species, including the genus Capsicum. One of the tools to ...counteract this biotic problem, which may be more profitable and respectful to the environment in the long term, is using biocontrollers such as Bacillus, Pseudomonas, Streptomyces (bacteria), and Trichoderma (fungus). It seems that each of these microorganisms has different mechanisms that allow them to inhibit and reduce the growth of P. capsici, negatively affecting the development of sporangia, germination and motility of zoospores, and expansion of germ tube. Although this direct biocontrol action on the phytopathogen correlates with the reduction of symptoms in Capsicum plants or other plant species, this would also involve the activation of defense responses in plants against P. capsici induced by microorganisms. The activity of several enzymes related to the isoflavonoid pathways and reactive oxygen species, as well as the expression of different genes that encode proteins related to pathogenesis and other proteins that can activate the jasmonic acid, salicylic acid, or ethylene signaling pathways. Despite the few existing works related to the biochemical and molecular interaction of Capsicum–P. capsici–biocontroller, in this review, we outlined and elucidated the possible effects and metabolic pathways related to this tripartite pathosystem.
Pineapple fruit production (Ananas comosus L. Merr.) is negatively affected by inhomogeneous natural flowering, but flowering can be exogenously induced by growth regulators such as Ethephon ...(2-chloroethylphosphonic acid), resulting in greater production and yield in this crop. Thus, this study aimed to evaluate the application of Ethephon and ethylene + activated carbon to increase flowering and the qualitative and yield components of pineapple. The experiment was set up in a randomized block design with three treatments and five replications (blocks). After checking that the variance of the data sets was homogeneous, they were subjected to analysis of variance. Subsequently, the difference between the means of the treatments was determined using the Tukey test (P ≤ 0.05). There was a significant difference in costs and gains between using and not using flowering inducers, representing a significant difference in the benefit-cost ratio (BCR). Therefore, the use of activated carbon + ethylene proved to be economically viable. We conclude that activated carbon associated with ethylene provided a higher percentage of flowering in pineapple fruit. However, this inducer and Ethephon were similarly effective in increasing yield in this crop.
Fungicide resistance is an alarming challenge for the Brazilian tropical agricultural systems, with major implications for food safety, human and animal health, as well as for the environment. This ...review explores strategies to address fungicide resistance within the Brazilian agroecosystem context. We examined historical and current scenarios of fungicide resistance in the Brazilian agroecosystems and the approaches to delay the emergence and mitigate the selection of resistant variants. Our review indicates that the prevalence of resistance in field populations of key plant pathogens in Brazil was due to failures in the implementation of preventive measures. To address this issue, alternative evolutionary-smart strategies against fungicide resistance are proposed, emphasizing institutional actions and public policies. Crucial steps involve strengthening national networks for large-scale foliar and seed fungicide efficacy testing and resistance monitoring, as well as imposing tighter restrictions on the labeling of high-risk single-active formulations. Additionally, the integration of non-chemical disease management strategies and the establishment of a centralized database and information system on fungicide resistance in Brazil are identified as essential for effective resistance monitoring and informed decision-making. To enhance fungicide resistance management, the adoption of a warning system (e.g., based on aerobiology- or on weather-monitoring) for predicting disease epidemics and minimizing fungicide applications is recommended. Increased funding, collaboration, mandatory reporting, and capacity building are required to overcome these challenges. In addition, promoting integrated disease management approaches is vital. By implementing these tailored strategies, Brazil can actively contribute to safeguarding its food safety, protecting human and animal health, and preserving the delicate balance of its unique agroecosystem. The adoption of evolutionary-smart strategies against fungicide resistance will prolong fungicide efficacy, reduce economic costs, and minimize environmental impacts, ensuring sustainable and resilient agriculture in Brazil.
Meloidogyne incognita root-knot nematode is one of the main causes of tomato root damage and consequently crop production losses. Thus, in in vitro conditions, the number of nematodes hatched eggs ...(%) at 4 and 6 days and nematode mortality (J2 stage) at 8, 18, and 24 h, were evaluated in Petri dishes containing the candidate rhizobacteria Enterobacter asburiae (BA4-19 and PM3-14), Acinetobacter calcoaceticus (BM2-12), Klebsiella variicola (BO3-4) and Serratia marcescens (PM3-8). The well-known Pseudomonas protegens (CHA0) and P. veronii (R4) were used as controls. In greenhouse conditions, plant height, root weight, and symptoms, as well as gall and nematode numbers, were determined in tomato plants infected by M. incognita and treated with the seven rhizobacteria. In addition, all variables were correlated using Pearson's analysis. In general, a significant correlation was observed among the variables of both experiments, showing the antagonistic capacity of the strains against nematode. It seems, that PM3-8 and PM3-14 strains reduce hatching, and cause mortality of nematodes J2 if compared with CHA0 and R4 strains. Likewise, tomato treated with BM2-12 strain shows a higher height and root weight, as well as a smaller number of galls and nematodes in their roots. This study provides evidence that PM3-8 and PM3-14 strains reduce the M. incognita egg hatching, and that the BM2-12 strain can be a plant growth-promoter potential of tomato plants.
Interaction among nitrogen fertilization using bovine manure, poultry manure, Jatropha curcas seed cake and urea, and the diseases Ramularia leaf spot (RLS) and Boll rot (BR), caused by Ramulariopsis ...pseudoglycines and Diplodia gossypina, respectively, in cotton plants (Gossypium hirsutum L.), was studied under field conditions. Intensity (incidence and severity in percentage) of RLS and incidence (%) of BR were evaluated over time, starting in reproductive stage B1 (first visible flower bud). A randomized complete block design with a 4x4 factorial arrangement was used (fertilizers x doses), totaling 16 treatments with four replications. Disease progress was analyzed with the nonlinear Logistic and Gompertz models, obtaining the epidemiological parameters amount of initial disease (Y0) and progress rate (r). Plants fertilized with 50 kg N ha-1, presented an incidence twice greater than those obtained with other fertilizers. The Logistic model better fits RLS, but no model could represent BR. Only the epidemiological parameters of RLS were affected differently in this experiment compared to BR disease. The possible role of organic and inorganic nitrogen fertilization in the RLS and BR management is discussed.
Wheat blast, caused by the ascomycetous fungus Pyricularia oryzae Triticum lineage (PoTl), is mainly controlled by fungicide use, but resistance to the main fungicide groups—sterol demethylase (DMI), ...quinone outside (QoI), and succinate dehydrogenase inhibitors (SDHI)—has been reported in Brazil. In order to rationalize fungicide inputs (e.g., choice, timing, dose-rate, spray number, and mixing/alternation) for managing wheat blast, we describe a new monitoring tool, enabling the quantitative measurement of pathogen’s inoculum levels and detection of fungicide resistance alleles. Wheat blast airborne spores (aerosol populations) were monitored at Londrina in Paraná State, a major wheat cropping region in Brazil, using an automated high-volume cyclone coupled with a lab-based quantitative real-time PCR (qPCR) assay. The objectives of our study were as follows: (1) to monitor the amount of PoTl airborne conidia during 2019–2021 based on DNA detection, (2) to reveal the prevalence of QoI resistant (QoI-R) cytochrome b alleles in aerosol populations of wheat blast, and (3) to determine the impact of weather on the dynamics of wheat blast aerosol populations and spread of QoI resistant alleles. PoTl inoculum was consistently detected in aerosols during the wheat cropping seasons from 2019 to 2021, but amounts varied significantly between seasons, with highest amounts detected in 2019. High peaks of PoTl DNA were also continuously detected during the off-season in 2020 and 2021. The prevalence of QoI resistant (QoI-R) cytochrome b G143A alleles in aerosol populations was also determined for a subset of 10 PoTl positive DNA samples with frequencies varying between 10 and 91% using a combination of PCR-amplification and SNP detection pyrosequencing. Statistically significant but low correlations were found between the levels of pathogen and the weather variables. In conclusion, for wheat blast, this system provided prior detection of airborne spore levels of the pathogen and of the prevalence of fungicide resistance alleles.
Chemical control is the most widely used method for disease management in significant crops such as soybeans and wheat. However, for a few years biological control has gained prominence. Thus, we ...evaluated the antagonism of bacteria Pseudomonas fluorencens, Pantoea aglomerans, and Bacillus sp. on the phytopathogens Corynespora cassiicola and Drechslera tritici-repentis, previously isolated from soybean and wheat leaves, respectively. The experiments were carried out under controlled conditions at the Phytobacteriology Laboratory of the Faculty of Agronomy and Veterinary Medicine (FAVM), University of Passo Fundo (UPF), Rio Grande do Sul, Brazil. The treatments were: T1: P. Fluorencens + pathogen; T2: P. aglomerans + pathogen; T3: Bacillus spp. + pathogen, and T4: pathogen (control). In each experiment (C. cassiicola and D. tritici-repentis), a completely randomized design with six replications was used. The data were submitted to linear regression analysis, obtaining the daily increase rate (slope). The final time data was submitted to the ANOVA, and the means were compared by the Tukey test (P < 0.05). P. fluorescens, P. agglomerans, and Bacillus sp. reduced mycelial growth by 74 and 87% of C. cassiicola and D. tritici-repentis, respectively. Although this study was carried out under in vitro conditions, it can serve as a basis for other biological control studies, especially about the management of leaf spots caused by C. cassiicola and D. tritici-repentis, under field conditions.
La mancha angular es una de las enfermedades foliares más comunes del cultivo de frijol en el sur de Brasil. El objetivo del trabajo fue evaluar el efecto del extracto de la macroalga Ulva fasciata ...en la severidad de la mancha angular, los niveles de pigmentos foliares y la productividad de los genotipos de frijol común IPR Uirapuru, CF 22 y Mouro graúdo, durante los años 2005 y 2006. Las plantas tratadas con el extracto de alga o el fungicida azoxistrobina se pulverizaron en los estados fenológicos V3, V5, R6 e R7. Plantas no tratadas se utilizaron como testigos. La severidad (%) de la enfermedad se estimó a partir del estado V3, para un total de seis evaluaciones cada año. Los valores de la severidad se calcularon como área bajo la curva de progreso de la enfermedad (ABCPE). En el 2006 se determinaron los pigmentos foliares (clorofila a, b, total y carotenoides) y en los dos años se evaluó el rendimiento de granos, aunque en el 2005 solamente se evaluó el peso de mil granos. En conclusión, el control que ejerce el extracto de U. fasciata sobre la mancha angular depende de la interacción biológica entre el genotipo de frijol y el ambiente. Por otro lado, el extracto no afectó el contenido de los pigmentos foliares ni la producción de granos.
La presente investigación busca caracterizar las unidades productivas agropecuarias (UPA) que producen soya, generar nueva información para la diversificación de cultivos y proyectar cambios en la ...matriz productiva de Ecuador. La información se recolectó a través de encuestas estructuradas entre julio de 2017 y enero de 2018 en los cantones Vinces, Quevedo, Puebloviejo y Babahoyo de la provincia de Los Ríos, ubicada en la cuenca media del Río Guayas. Se entrevistaron 337 productores de soya y las preguntas abordaron aspectos económicos, socioculturales y ecológicos. La producción de granos se consideró aceptable (por encima de la media nacional con 2,7 t/ha) y la comercialización se estimó en $5.610/t, con una inversión en efectivo de $432/ha. La edad promedio de los productores fue de 51 años y es preocupante la falta de empoderamiento de los hijos de agricultores respecto a las actividades agrícolas. Se registró un bajo porcentaje de analfabetismo, factor positivo al momento de emprender procesos de capacitación. La mayoría de los agricultores están agrupados en organizaciones agrícolas, principalmente para acceder a los beneficios de subsidios establecidos por el Gobierno, y poseen acceso medio a servicios básicos. Los agricultores de la zona dependen de insumos externos como las semillas, lo que constituye un factor negativo para la sostenibilidad del sistema productivo.
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