Integrated Disease Management Research Articles

Impacts of a Commercially Available Horticultural Oil Biopesticide (EF-400) on the Tomato-Phytophthora infestans Pathosystem.

Biopesticide fungicides are naturally derived compounds that offer protection from plant diseases through various modes of action, including antimicrobial activity and upregulation of defense responses in host plants. These plant protectants provide a sustainable and safe alternative to conventional pesticides in integrated disease management programs and are especially salient in the management of high-risk and economically important diseases such as late blight of tomato and potato, for which host resistance options are limited. In this study, a commercially available biopesticide, EF400 comprised of clove (8.2%), rosemary (8.1%), and peppermint oils (6.7%) (Anjon AG, Corcoran, CA), was investigated for its effects on the Phytophthora infestans-tomato pathosystem. Specifically, we evaluated the impact of EF400 on P. infestans growth in culture, disease symptoms in planta, and activation of host defenses through monitoring transcript accumulation of defense-related genes. The application timing and use rate of EF400 were further investigated for managing tomato late blight. EF400 delayed the onset of tomato late blight symptoms, although not as effectively as the copper hydroxide fungicide Champ WG (Nufarm Americas Inc., Alsip, IL). Pathogen mycelial growth and sporangial quantity on late blight-susceptible tomato leaves were significantly reduced with EF400. The biopesticide also had an enhancing or suppressing effect on the transcript accumulation of three defense-related genes: Pin2, PR1a, and PR1b. Our work in exploring a commercially available horticultural oil biopesticide meaningfully contributed to the essential knowledge base for optimizing recommendations for the management of tomato late blight.

Role of Chitosan in Post Harvest Disease Management

Post harvest losses due to microbial spoilage remain a significant challenge in agriculture, affecting both food security and economic sustainability. Chitosan, a biopolymer derived from chitin, showed potential in recent years as a means of reducing post harvest diseases in fruits and vegetables. This review investigates into the complex role that chitosan plays in managing post harvest diseases. It emphasises the antimicrobial qualities, capacity to trigger defence mechanisms in plants, development of physical barriers, regulation of enzymatic activity, compatibility with biological control agents, and ecological sustainability of chitosan. Chitosan based treatments offer an environmentally sustainable approach to prolonging the period of the shelf life of produce by effectively preventing the growth of microbes, enhancing the plant's natural resistance to pathogens, and maintaining post harvest quality. Understanding the mechanisms underlying the efficacy of chitosan in disease management is essential for optimizing its application and integrating it into integrated disease management strategies in agricultural practices.

Genetic Diversity, Mycotoxin Profiles, and Population Structure of Fusarium spp. Associated with Fusarium Head Blight in Georgia, United States.

Fusarium head blight (FHB) has become a limiting factor in soft red winter wheat production in the southeast United States. Recent epidemics have occurred in Georgia, but genetic information on the Fusarium species responsible for FHB is unknown. This study aimed to assess pathogen population structure and genetic diversity, trichothecene profiles, and representative pathogenicity of 196 Fusarium isolates collected from 44 wheat (n = 85) and 53 corn (n = 111) fields in Georgia. Phylogenetic analysis using the translation elongation factor 1-alpha (635 bp) and RNA polymerase second largest subunit (930 bp) sequence data resolved isolates into 185 haplotypes, which represented 12 Fusarium species grouped under five species complexes. F. graminearum with 15-acetyl-deoxynivalenol (15ADON) chemotype (75.6%) and F. incarnatum (57.7%) predominated in wheat and corn, respectively, with a surprisingly higher frequency of nivalenol (NIV) F. graminearum (21.8%). Using nine variable numbers of tandem repeat markers, 82 multilocus genotypes out of 86 F. graminearum isolates were identified and grouped into two genetic clusters, pop1fg (n = 29) and pop2fg (n = 32), as part of the North American populations (NA1 and NA2) but with no chemotype differentiation. F. graminearum populations in Georgia are mostly clonal and might have evolved through at least two introductions from the northeast United States and Canada and local adaptation to maintain high genetic diversity. Pathogenicity of F. graminearum isolates from wheat and corn had high FHB severity (>60%) in wheat, which depicted the risk they can pose towards future FHB outbreaks. Overall, this baseline study provided important information on Fusarium species diversity including F. graminearum associated with FHB in Georgia that will be useful to formulate integrated disease management incorporating improved host resistance and fungicide spray programs.

Development and validation of a standard area diagram set to assess corn grey leaf spot severity and foliar fungicide control efficacy

AbstractGrey leaf spot (GLS), caused by Cercospora spp., has become a very important foliar disease for second‐crop corn season, mainly in South America. Therefore, this study aimed to develop and validate a standard area diagram set (SADs) to estimate the severity of GLS and to apply the SADs established in this study to evaluate the efficacy of fungicides for GLS control in field trials. The SADs with nine levels of severity (0.5; 2; 5; 10; 20; 30; 40; 50 and 60%) improved accuracy, precision and reliability. To evaluate the control of GLS in corn, two experiments spraying chemical fungicides were conducted, one in Rio Verde (GO) (experiment A) and another in Chapadão do Sul (MS) (experiment B). Both experiments were conducted in randomized block design, with 10 treatments and four replicates. For the severity assessment, the SADs elaborated in this study was used. From this severity data over time, disease progress curves, area under the disease progress curve (AUDPC), and yield were obtained. Based on the AUDPC and yield values, all treatments differed from the control. The fungicide fluxapyroxad + pyraclostrobin + mefentrifluconazole had the highest value, giving 72.8% control efficacy and the highest yield maintenance of 43.5%. The other treatments had an intermediate control efficacy and yield. The SADs proposed here is a useful tool for improving visual assessments of GLS severity on corn leaves and fungicides can be used for integrated disease management.

Factors associated with the timely diagnosis of malaria and the utilization of types of healthcare facilities: a retrospective study in the Republic of Korea.

This study aimed to analyze trends in the timely diagnosis of malaria cases over the past 10 years in relation to the utilization of different types of healthcare facilities. The study included 3,697 confirmed and suspected cases of malaria reported between January 1, 2013, and December 31, 2022, in the national integrative disease and healthcare management system. Some cases lacking a case report or with information missing from the case report were excluded from the analysis. A generalized linear model with a Poisson distribution was constructed to estimate risk ratios and 95% confidence intervals adjusted for other variables, such as distance. When cases involving diagnosis >5 days after symptom onset in confirmed patients (5DD) were examined according to the type of healthcare facility, the risk ratio of 5DD cases was found to be higher for tertiary hospitals than for public health facilities. Specifically, the risk ratio was higher when the diagnosis was established at a tertiary hospital, even after a participant had visited primary or secondary hospitals. In an analysis adjusted for the distance to each participant's healthcare facility, the results did not differ substantially from the results of the crude analysis. It is imperative to improve the diagnostic capabilities of public facilities and raise awareness of malaria at primary healthcare facilities for effective prevention and control.

Viral Threats to Fruit and Vegetable Crops in the Caribbean.

Viruses pose major global challenges to crop production as infections reduce the yield and quality of harvested products, hinder germplasm exchange, increase financial inputs, and threaten food security. Small island or archipelago habitat conditions such as those in the Caribbean are particularly susceptible as the region is characterized by high rainfall and uniform, warm temperatures throughout the year. Moreover, Caribbean islands are continuously exposed to disease risks because of their location at the intersection of transcontinental trade between North and South America and their role as central hubs for regional and global agricultural commodity trade. This review provides a summary of virus disease epidemics that originated in the Caribbean and those that were introduced and spread throughout the islands. Epidemic-associated factors that impact disease development are also discussed. Understanding virus disease epidemiology, adoption of new diagnostic technologies, implementation of biosafety protocols, and widespread acceptance of biotechnology solutions to counter the effects of cultivar susceptibility remain important challenges to the region. Effective integrated disease management requires a comprehensive approach that should include upgraded phytosanitary measures and continuous surveillance with rapid and appropriate responses.

An innovative patient-centred approach to heart failure management: the Best Care heart failure integrated disease management program

BackgroundThe management of heart failure (HF) is challenging because of the complexities in recommended therapies. Integrated disease management (IDM) is an effective model, promoting guideline directed care, however, the impact of IDM in the community setting requires further evaluation. MethodsA retrospective evaluation of community-based IDM. Patient characteristics were described, and evaluation of outcomes using a pre- and post-intervention design were HF-related health service use, quality of life, and concordance with guideline-directed medical therapy (GDMT). Results715 patients were treated in the program (2016 to 2023), 219 in a community specialist clinic and 496 in 25 primary care clinics. The overall cohort was predominantly male (60%), mean age of 73.5 years (±10.7), and 60% with HF reduced ejection fraction.In patients with ≥6 months of follow-up (N=267), pre vs post annualized rates of HF-related acute health services decreased from 36.3 to 8.5 hospitalizations/100 patients/year, p<0.0001, 31.8 to 13.1 ED visits/100 patients/year, p<0.0001, and 152.8 to 110.0 urgent physician visits/100 patients/year, p=0.0001. GDMT improved; patients receiving triple therapy and quadruple therapy increased by 10.1% (95%CI;2.4%,17.8%) and 19.6% (95%CI;12.0%,27.3%), respectively. Within these groups optimal dosing was achieved in 42.5% (95%CI;32.0%,53.6%) and 35.0% (95%CI;23.1%,48.4%), respectively. In patients with at least one follow-up (N=286) over 50% experienced a clinically relevant improvement in quality of life. ConclusionA community-based IDM program for HF, may reduce HF-related acute health service use, improve quality of life and GDMT. These encouraging preliminary outcomes from a real-world program evaluation require confirmation in a randomized controlled trial.

Efficacy of different fungicides against Ascochyta rabiei and Botrytis cinerea associated with chickpea

Ascochyta rabiei and Botrytis cinerea have been reported to cause blight and gray mold diseases in chickpea in different parts of the world and cause a significant economic loss to crop. In the present investigation, an in vitro evaluation of fungicides was conducted to find out the sensitivity and fungicide concentration in inhibiting the growth of Ascochyta rabiei and Botrytis cinerea. In vitro evaluation of fungicides revealed that, among five fungicides, bavistin (carbendazim 50 WP) a systemic fungicide was highly effective in inhibiting the mycelial growth with 100% inhibition at all the concentrations tested followed by baycor (bitertenol WP (25% w/w), with 98.88% inhibition at 500 ppm concentration and captan with 80% mycelia growth inhibition in A.rabiei. The fungicides such as chlorothalonil, copper oxychloride, and bitertanol at all concentrations were ineffective against B. cinerea. The fungicides that were effective under laboratory conditions could be further evaluated under field conditions to validate their efficacy and they could be incorporated as a component in integrated disease management in chickpea.

Interplay of plant pathogens and host defenses: Unveiling the mechanisms and strategies for crop protection

Plant pathogens, encompassing a diverse array of microbes including fungi, nematodes, protozoa, bacteria, and viruses, represent a significant threat to agricultural stability by compromising plant health. These microorganisms engage in a complex battle against plant immune systems, leading to diseases that can drastically diminish crop yields, degrade product quality, and in extreme cases, cause total crop failure. A comprehensive understanding of the mechanisms underlying plant infection, the specific pathogens involved, and the strategy for effective prevention is crucial for agricultural sustainability. This review paper provides a detailed examination of the multifaceted interactions between plant pathogens and their hosts, focusing on the entry mechanisms, symptom development, and prevention strategies against plant diseases. Major findings reveal the intricate ways pathogens interact with plant immune responses, the critical role of environmental factors in disease outbreaks, and the effectiveness of integrated disease management approaches. The paper concludes with a novel perspective, emphasizing the urgent need for sustainable, science-based strategies to enhance plant resistance, safeguard food security, and mitigate the economic consequences of plant pathogenic diseases. This synthesis not only advances our understanding of plant pathology but also sets a framework for future research directions in plant disease management.

Strategies for managing fungicide resistance in the Brazilian tropical agroecosystem: Safeguarding food safety, health, and the environmental quality

AbstractFungicide 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.

Reaction of Selected Citrus Cultivars to Pseudocercospora Leaf and Fruit Spot Disease Under Natural Infection in Northern Uganda

Citrus is an important crop among many resource constrained subsistence farmers living in rural areas of Uganda. Citrus production is affected mainly by drought, declining soil fertility, pests and diseases. Among diseases, citrus leaf and fruit spot disease caused by fungus Pseudocercospora angolensis is currently one of the major constraints to the production of citrus in Uganda where millions of people rely on the crop for nutritional security and household income. The disease can lead to 50-100% fruit yield loss depending on environmental conditions, disease management and weather conditions. In order to identify resistance to P. angolensis, a study was conducted to identify variability for citrus leaf and fruit spot resistance from adapted commercial cultivars as an initial step in developing integrated disease management strategy. Six cultivars were assessed. The screening was under natural infection conditions in disease hot spots in northern Uganda in 2014a and 2014b seasons. The results showed significance difference (p &amp;lt; 0.01) for Area Under Disease Progressive Curve (AUDPC) for number of leaves with P. angolesnis symptoms and number of lesions. Subsequently, the study identified Kuno as resistant and Tangelo as less susceptible to Pseudocercospora leaf and fruit spot infection, and they could be recommended for citrus leaf and fruit spot disease control.

Integrated Management of Pathogens and Microbes in Cannabis sativa L. (Cannabis) under Greenhouse Conditions

The increased cultivation of high THC-containing Cannabis sativa L. (cannabis), particularly in greenhouses, has resulted in a greater incidence of diseases and molds that can negatively affect the growth and quality of the crop. Among them, the most important diseases are root rots (Fusarium and Pythium spp.), bud rot (Botrytis cinerea), powdery mildew (Golovinomyces ambrosiae), cannabis stunt disease (caused by hop latent viroid), and a range of microbes that reduce post-harvest quality. An integrated management approach to reduce the impact of these diseases/microbes requires combining different approaches that target the reproduction, spread, and survival of the associated pathogens, many of which can occur on the same plant simultaneously. These approaches will be discussed in the context of developing an integrated plan to manage the important pathogens of greenhouse-grown cannabis at different stages of plant development. These stages include the maintenance of stock plants, propagation through cuttings, vegetative growth of plants, and flowering. The cultivation of cannabis genotypes with tolerance or resistance to various pathogens is a very important approach, as well as the maintenance of pathogen-free stock plants. When combined with cultural approaches (sanitation, management of irrigation, and monitoring for diseases) and environmental approaches (greenhouse climate modification), a significant reduction in pathogen development and spread can be achieved. The use of preventive applications of microbial biological control agents and reduced-risk biorational products can also reduce disease development at all stages of production in jurisdictions where they are registered for use. The combined use of promising strategies for integrated disease management in cannabis plants during greenhouse production will be reviewed. Future areas for research are identified.

Integrated disease management modules for rice-bacterial leaf blight ecosystem under rice: Wheat cropping system

Integrated disease management modules for rice-bacterial leaf blight ecosystem under rice: Wheat cropping system

Survey of Major Diseases on Medicinal and Aromatic Plants Growing Areas of Ethiopia

Medicinal and aromatic plants are industrial plant that are primarily used for therapeutic, aromatic and culinary purposes as components of cosmetics, medicinal products, health foods and other natural health products. Like other cereal crops, these potential medicinal and aromatic plants are constantly in grave danger from disease attack. The aim of this study was to assess the most prevalent diseases on prioritized medicinal and aromatic plants. Survey was conducted at Wondo Genet Agricultural research stations and herb growing companies in Ethiopia. Survey fields were observed from vegetative to maturity stage of the plant to assess the pest status. A total of 11 medicinal and aromatic plants were assessed in four different locations and these herbs were attacked by various diseases. Rust disease was the most serious problem on Aloe vera and Lemon grass, accounting for 30-40 percent of disease severity at Wondo Genet. In Butajira, powdery mildew was the most common disease found on sage, with a 20 percent severity. Downy mildew was recorded as a major disease on basil plants in Hawassa and Debre Zeit, with a 30-35 percent severity. Therefore, identification of the pathogen&amp;apos;s causing agents and integrated disease management for the major recorded diseases of medicinal and aromatic plants needs further research.

Management of Fusarium Wilt of Tomato (Fusarium oxysporum f. sp. lycopersici) and Related Soil-borne Diseases using Eco-friendly Methods: A Review

Tomato is rich in vitamins, minerals and contains anti-oxidant compounds, like vitamin C and lycopene that has significant role in human health as it has anti-cancer properties. Tomato production is significantly affected by several factors amongst which Fusarium Wilt is one of the major and widespread fungal soil borne diseases in Nigeria. Difficulty in controlling this disease is attributable to long survivability of the pathogen and its existence in diverse pathogenic races. Conventional strategies, such as the use of resistant cultivars and synthetic fungicides, are not completely effective in managing tomato wilt caused by Fusarium oxysporum f. sp. lycopersici and because of unintended effects of chemicals on the environments its application is highly cautioned. This paper has examined many non-pesticide approaches such as application of bio-control agents, use of suppressive soils, composts/vermicomposts and their extracts, animal manure and urine, soil solarization, botanical extracts, good agricultural practices and integrated disease management strategy to control Fusarium wilt and other related soil borne diseases. It is worth noting that no single method can effectively control such diseases. In order to achieve a sustainable and eco-friendly disease management strategy the use of integrated approach is highly recommended. This review will provide farmers with diverse methods to be integrated as management package for Fusarium wilt and related diseases.

Analysis of Clinical Characteristics of Tuberculosis Patients with Dementia in Gyeongsangbuk-do, Republic of Korea.

(1) Background: Among Korean research papers there have been studies on the correlation between tuberculosis-hypertension and diabetes and the correlation between dementia-hypertension and diabetes, but there were no analysis data specifically on tuberculosis and dementia. (2) Methods: A total of 2992 tuberculosis patients in the Gyeongbuk region were analyzed through a final analysis of integrated disease and health management system data collected from 2021 to 2022. In this selection, patients with tuberculosis under 50 years of age and 368 people diagnosed with tuberculosis were excluded. (3) Results: From 2021 to 2022, among the 2992 tuberculosis patients in Gyeongsangbuk-do aged 50 or older, 2722 (91.0%) belonged to the general tuberculosis patient group, while 270 (9.0%) belonged to the dementia-tuberculosis patient group. The average age in the dementia-tuberculosis group was 81.4 years, significantly higher than the general group's average of 75.7 years. Within the dementia-tuberculosis patient group, 235 patients (87.0%) had underlying medical conditions in addition to dementia and tuberculosis. The tuberculosis treatment cure rate was 56.3% (1477 patients) in the general group and 38.9% (105 patients) in the dementia-tuberculosis patient group. (4) Conclusions: The cure rate was notably higher in the general group. Similarly, the mortality rate (deaths due to tuberculosis) was significantly higher in the dementia-tuberculosis patient group (7.0%, 19 patients) compared to the normal group (3.0%, 81 patients). The mortality rate in the dementia group was more than twice that of the general group.

Prevalence of Rice Sheath Blight Disease in Cauvery Command Area of Karnataka, India

Among the various disease of rice, sheath blight caused by Rhizoctonia solani Kuhn has become one of the major fungal diseases covering different rice growing ecosystem of Cauvery command area of Karnataka. Roving disease survey was conducted during Kharif-2022 to know the occurrence and spread of sheath blight disease in Cauvery command area of Karnataka i.e. Mandya, Hassan, Mysuru and Chamarajnagara. Among the four districts surveyed, disease severity (%) was found highest in Hassan district with a mean disease severity of 22.86% which is followed by Mandya (19.90%), Mysuru (19.39%) and least disease severity was recorded in Chamarajnagara (12.54%). The high severity of sheath blight might be due to the highly favourable factors like high relative humidity, less temperature and water stagnation in these locations during the period of survey. Large scale cultivation of susceptible varieties as mono crop continuously on the same field might have increased the possibility of perpetuating the pathogen in the crop debris. This study can serve as basic to evaluate location specific integrated disease management strategy against sheath blight disease of rice.

Standard area diagrams for pecan leaf scab: Effect of rater experience and location, and leaf size on reliability and accuracy of visual estimates.

Assessments of the severity of scab (Venturia effusa), an economically significant disease of pecan, are critical for determining pecan cultivar susceptibility, disease epidemiology, and integrated disease management approaches. We developed a standard area diagram (SAD) set to aid in assessments of pecan leaflet scab. Leaflets with scab lesions were harvested and scanned using a flatbed scanner at 600 dpi, and Fiji (ImageJ) was used to determine the actual percent disease severity. The SADs had 10 leaflets ranging in severity from 0.2 to 48.9%. Forty 'small' (1.34 - 7.43 cm2) and forty 'large' (7.67 - 25.9 cm2) leaflet images were randomized for rater assessments. The images were assessed twice by 36 raters, first without and then with the SADs as a guide. Data were subjected to analysis using Lin's Concordance Correlation Coefficient (LCC, pc) to determine the accuracy of ratings, and by Intra-class Correlation Coefficient analysis to determine inter-rater reliability. The effects of rater experience, rater location, and leaflet size were also determined. The SADs significantly improved the agreement between raters and the actual values (LCC, pc = 0.70 and 0.84 without and with the SADs, respectively). The reliability of estimates was improved (ICC = 0.54 and 0.82 without and with the SADs, respectively). The effect of rater location on overall concordance was significant without and with the SADs based on an analysis of variance (ANOVA) using a general linear model and lsmeans separation (P<0.05). A generalized linear mixed model analysis revealed that there was a significant interaction between rater location, experience, and the use of the SADs, with some raters having greater improvement in generalized bias and concordance. Raters had a significantly better accuracy when rating 'small' leaves (LCC, pc = 0.86) compared to 'large' leaves (LCC, pc = 0.82) when using the SADs, highlighting the impact of psychophysics on field evaluations of plant disease severity. The proposed SADs will serve as an improved tool for performing pecan leaflet scab assessments by the pecan research community.

Chemical composition, antioxidant properties, and antifungal activity of wild Origanum elongatum extracts against Phytophthora infestans.

Phytophthora infestans, the causative agent of late blight disease, has gained notoriety for its destructive potential, leading to substantial losses in potato yields. Although conventional systemic fungicides have been shown to be effective in controlling plant pathogens, growing environmental concerns have prompted the need for more integrated disease management approaches. Hence, in this study, the effectiveness of wild Origanum elongatum extracts as biopesticides was explored in controlling P. infestans and potentially mitigating its devastating impact in planta. The aerial parts of O. elongatum were subjected to sequential extraction using water, hexane, chloroform, and methanol. The obtained extracts were tested in vitro through the poisoned food procedure for their capacity to obstruct P. infestans growth and to defeat potato blight severity in vivo. The phyto-contents (total phenolic content (TPC) and total flavonoid content (TFC)), as well as the antioxidant activities, were spectrophotometrically determined in all extracts, and the phytoconstituents of the most active extract (methanolic extract) were profiled via high-performance liquid chromatography-photodiode array-tandem mass spectrometry (HPLC-PDA-MS/MS). In vitro, the complete inhibition rate of the P. infestans was obtained using the methanolic extract at 5 mg/mL, followed by the hexane and chloroform extracts at 10 mg/mL. Interestingly, complete inhibition of the pathogen was achieved upon the application of the aqueous extract at 10 mg/mL. In vivo, the aqueous extract at 25 mg/mL reduced the P. infestans severity rate to 27.25%, while the methanolic extract at 20 mg/mL led to the lowest severity rate. Moreover, the hexane and chloroform extracts impaired the pathogen severity rate to 50% and 41% using 20 mg/mL, respectively. The TPC and TFC in the extracts were variable with high concentrations detected in the methanolic extract with 485.42 mg GAE/g and 58.24 mg QE/g, respectively. In addition, the methanolic extract showed the highest antioxidant activities, while the chloroform extract exhibited the lowest activity. Liquid chromatography (LC)-MS/MS analysis of the methanol extract revealed 56 components from diverse classes. These included organic acids, phenolic acids, flavonoids, tannins, and coumarins. These findings suggest that O. elongatum could be investigated as a potential source of antifungal compounds targeting different phytopathogens.

Microbial Interactions in the Management of Groundnut Stem Rot

Groundnut (Arachis hypogaea L.) is an important oil seed crop in the world belonging to the Leguminosae family. It is one of the essential food and cash crops of our country. In India, a large number of diseases attack groundnut [1]. Among soil borne diseases, stem rot or white mold caused by Sclerotium rolfsii Sacc. [2] is an important disease causing significant yield losses in several groundnut growing countries (Mehan et al., 1994). Sclerotium rolfsii Sacc. is a destructive soil borne fungal pathogen of oil seed crop in India. Different practices are recommended for management of groundnut stem rot such as deep summer ploughing, destruction of plant debris, crop rotation with jowar and bajra, seed treatment with carbendazim or captan or mancozeb or tebuconazole, soil drenching with hexaconazole, application of ammonium sulphate or calcium ammonium nitrate instead of urea and application of gypsum at flowering stage. Further, no single treatment is full proof and disease continues to cause losses in farmers’ fields. Biological control offers an interesting alternative to fungicides for sustainable management of soil borne diseases. Biocontrol is a non-chemical measure, could be effective as chemical control by various techniques. Among the techniques, the mixture of antagonists was studied to enchance the control efficacy. In most studies, the involvement of only mechanism of biological control is demonstrated. Involvement of more than one mechanism has been reported in only a few systems. Use of several biocontrol agents with several mechanisms of control fits in well with the concepts of integrated disease management, in which several means of disease suppression are applied concurrently. When single or more means of mechanisms are not effective, the others may compensate for the former absence. The present study, involved three major bacterial antagonists viz., Streptomyces violaceusniger, Streptomyces exfoliatus and Pseudomonas fluorescens to find out the effective dose of mixtures. The different doses from 10-1 to 10-5 were studied, the dose 10-1 of Streptomyces violaceusniger have more efficiency of 86.70, than S. exfoliatus. The efficacy of Streptomyces violaceusniger with combination of other antagonists were tested and found that, the mixture of Streptomyces violaceusniger and P. fluorescens have synergistic activity than any other combinations which have synergistic factor greater than one.