Due to the pathogen’s ability to survive in the soil for longer durations, soil-borne diseases are often difficult to control. This study investigates the multifaceted impacts of biochar on the management of stem rot disease in groundnut and its influence on soil properties and microbial communities. The effects of biochar at different concentrations, such as 0%, 1%, 3%, and 5% on groundnut stem rot disease incited by Sclerotium rolfsii were evaluated thoroughly. Under laboratory conditions, biochar exhibited no direct inhibitory effects on S. rolfsii at varying concentrations but revealed an indirect suppression of sclerotial body production, suggesting a concentration-dependent influence on pathogen resting structures. Further, it was observed that biochar treatments effectively delayed symptom onset and reduced disease progression in groundnut plants, with significant variation observed among genotypes and biochar concentrations. Notably, interactions involving genotypes ICGV 171002 and ICGV 181035 with BC2 + Sr (3% conc. of biochar + S. rolfsii) and BC3 + Sr (5% conc. of biochar + S. rolfsii) treatments showed superior efficacy in disease reduction under controlled conditions. Field evaluations confirmed these findings, highlighting genotype-specific responses to biochar treatments. However, no significant difference was observed between BC2 + Sr (3%) and BC3 + Sr (5%) treatments in managing stem rot disease compared to controls. Biochar application significantly increased soil nutrient levels, including nitrogen, phosphorus, and potassium, and increased soil organic matter content, EC, pH, emphasizing its potential to improve soil fertility. Overall, these findings highlight the potential benefits of biochar for sustainable agriculture through disease management, soil nutrient enrichment, and microbial modulation, warranting further investigation into optimal application strategies across different agricultural contexts.

Storage is an important aspect of groundnut, as the in-shell and shelled kernels are prone to infestation by insects, pests, and fungi. Among several storage pests, the groundnut bruchid, Caryedon serratus, causes serious losses. Farmers often resort to different management practices, including hermetic storage, to control it. The moisture content of the commodity plays an important role in insect infestation during storage. Drying to safe moisture levels before storage is known to prevent the activity of various living organisms, such as storage pests. However, drying to low levels of moisture may not be economical for farmers, as they may not have access to devices to accurately check product moisture. In this regard, we wanted to demonstrate the efficacy of triple-layer hermetic storage bags in preventing the damage caused by C. serratus when the groundnuts are stored at intermediate (10%) and high (14%) levels of moisture compared to traditionally used bags such as polypropylene bags and jute bags. Groundnut pods at 10% moisture content and 14% moisture content were separately inoculated with adult bruchids and a toxigenic strain of Aspergillus flavus fungal inoculum before storing them for 6 months. Results from groundnut samples taken at two-month intervals indicated that groundnut pods stored in triple-layer hermetic bags were completely free from infestation by C. serratus by recording a zero number of eggs laid, number of pupae, adult emergence, percentage of loss, and percentage of damage up to 6 months of storage, by creating low oxygen (hypoxia) and high carbon dioxide (hypercarbia) conditions. Results also indicate no loss of pod weight stored in triple-layer bags, but a slight reduction in germination percentage was recorded due to a slight increase in fungal activity, but the reduction was significantly less in triple-layer plastic bags compared to other bag types. Similarly, biochemical constituents such as oil and protein content were slightly reduced in triple-layer plastic bags when pods were stored at a 10% moisture level, but a higher reduction was observed at a 14% moisture level. However, the reduction was very high and significant in other bag types at both 10 and 14% moisture levels.

Macrophomina phaseolina is the most devastating and emerging threat to groundnut production in India. An increase in average temperature and inconsistent rainfalls resulting from changing climatic conditions are strongly believed to aggravate the disease and cause severe yield losses. The present study aims to conduct a holistic survey to assess the prevalence and incidence of dry root rot of groundnut in major groundnut growing regions of Southern India, viz., Andhra Pradesh, Telangana, Karnataka, and Tamil Nadu. Furthermore, the pathogenic variability was determined using different assays such as morphological, cultural, pathogenic, and molecular assays. Results indicate that disease incidence in surveyed locations ranged from 8.06 to 20.61%. Both temperature and rainfall played a major role in increasing the disease incidence. The pathogenic variability of M. phaseolina isolates differed significantly, based on the percent disease incidence induced on cultivars of JL-24 groundnut and K-6 groundnut. Morphological variations in terms of growth pattern, culture color, sclerotia number, and sclerotia size were observed. The molecular characterization of M. phaseolina isolates done by ITS rDNA region using ITS1 and ITS4 primers yielded approximately 600 bp PCR amplicons, sequenced and deposited in GenBank (NCBI). Molecular variability analysis using SSR primers indicated the genetic variation among the isolates collected from different states. The present investigation revealed significant variations in pathogenic variability among isolates of M. phaseolina and these may be considered important in disease management and the development of resistant cultivars against groundnut dry root rot disease.

Pigeonpea (Cajanus cajan) is one of the important grain legume crops cultivated in the semi-arid tropics, playing a crucial role in the economic well-being of subsistence farmers. India is the major producer of pigeonpea, accounting for over 75% of the world’s production. Sterility mosaic disease (SMD), caused by Pigeonpea sterility mosaic virus (PPSMV) and transmitted by the eriophyid mite (Aceria cajani), is a major constraint to pigeonpea cultivation in the Indian subcontinent, leading to potential yield losses of up to 100%. The recent characterization of another Emaravirus associated with SMD has further complicated the etiology of this challenging viral disease. This review focuses on critical areas, including the current status of the disease, transmission and host-range, rapid phenotyping techniques, as well as available disease management strategies. The review concludes with insights into the future prospects, offering an overview and direction for further research and management strategies.

Groundnut bud necrosis orthotospovirus (GBNV), a tripartite single-stranded RNA virus, poses a significant threat to United States agriculture. GBNV is a quarantine pathogen, and its introduction could lead to severe damage to economically important crops, such as groundnuts, tomatoes, potatoes, peas, and soybeans. For the rapid and accurate detection of GBNV at points of entry, TaqMan reverse transcriptase–quantitative polymerase chain reaction (RT-qPCR) assays were developed and the results validated using conventional reverse transcriptase–polymerase chain reaction (RT-PCR) followed by Sanger sequencing. These assays target highly conserved regions of the nucleocapsid (NP) and movement (MP) proteins within the viral genome. Multiplex GBNV detection assays targeting the NP and MP genes, as well as an internal control plant gene, ACT11, showed efficiency rates between 90% and 100% and R² values of 0.98 to 0.99, indicating high accuracy and precision. Moreover, there was no significant difference in sensitivity between multiplex and singleplex assays, ensuring reliable detection across various plant tissues. This rapid, sensitive, and specific diagnostic assay will provide a valuable tool at ports of entry to prevent the entry of GBNV into the United States.

Stem rot, caused by the soil-borne pathogen Sclerotium rolfsii, pose a serious challenge in the groundnut (Arachis hypogaea L) cultivation. Although this disease is widespread globally but had most adverse impact in groundnut growing regions of United States, India, and Australia. The pathogen primarily targets the crown region of the plant, resulting in systemic collapse and potentially leading to yield losses up to 80%. Effective genetic control measures are essential to mitigate the impact of this disease on groundnut production. Realizing the time and resource-consuming complex field-based phenotyping, the availability of easy and repeatable phenotyping methods may fasten the process of donor and gene discovery efforts. Multi-season phenotyping was performed for stem rot on 184 minicore germplasm accessions, including checks, under two conditions: sick field screening and response to oxalic acid assay. This study demonstrated medium to high heritability (52–63% broad-sense heritability) and significant environmental influence (36%). The response to the oxalic acid assay showed a high proportion of similarity (approximately 80%) with the percent mortality observed in the sick field indicating an easy way of performing precise phenotyping. Notably, seven genotypes—ICG163, ICG721, ICG10479, ICG875, ICG11457, ICG111, and ICG2857—exhibited stable resistance, with less than 30% mortality against stem rot disease. Among these, ICG163, ICG875, and ICG111 displayed low mortality and consistent stability across multiple seasons in both the sick field and controlled conditions of the oxalic acid assay. The oxalic acid assay developed in this study effectively complements field phenotyping, as a reliable method for assessing stem rot resistance. Seven resistant genotypes identified through this assay can be utilized for the introgression of stem rot resistance into elite genotypes. Given the significant influence of the environment on stem rot resistance, it is essential to implement multi-season phenotyping to obtain precise results. Furthermore, the response to oxalic acid serves as a valuable supplement to traditional field phenotyping, since maintaining uniform disease pressure during field screenings is often challenging.