<div style="text-align:justify">Background: Groundnut (Arachis hypogaea L.) is an important legume crop of tropical and sub-tropical areas of the world. This crop suffers from several diseases like early leaf spot, late leaf spot, rust, groundnut bud necrosis, peanut clump and collar rot etc. But collar rot caused by Aspergillus niger van Teighem is one of the most important seed and soil borne diseases causing huge economic (40-50 per cent) loss in India and abroad. 
 
Methods: A roving survey was conducted to assess the incidence of collar rot in eight major groundnut growing districts of western Rajasthan i.e. Bikaner, Jodhpur, Churu, Jalore, Jaipur, Sikar, Nagaur and Dausa during Kharif 2018. A field experiment was carried out for two consecutive years (2019 and 2020) to manage the disease through altering micro-climate under canopy with six levels of seed rates (80, 85, 90, 95, 100 and 105 kg/ha). 
 
Result: Our investigations cleared that this disease is prevalent in all the 200 fields surveyed in eight districts of Rajasthan with 22.99 per cent overall disease incidence which varied from 17.84 to 32.38 per cent with monetary losses. Maximum disease incidence was recorded in Jaipur (28.85%) district while it was lowest in Nagaur district (20.15%). Higher disease reduction (12.97%) with increased pod yield (27.65%) was observed with higher seed rate of 105 kg/ha as compared to standard recommended seed rate (80 kg/ha) as this pathogen is favoured by higher temperature and low soil moisture, dense canopy provides shade that increases humidity under the cropped area and lowers temperature. As a result of this, plant mortality can be compensated by increasing plant population through seed rate, as it modifies the microclimate and generate an environment which is less favourable for developing collar rot disease of groundnut.</div>

​​Incidence of Collar Rot of Groundnut in Rajasthan and its Management

<div style="text-align: justify;">Sunflower (Helianthus annuus L.) is an important short duration crop which can be grown in all seasons and produces high quality edible and industrial oil, besides animal feed and fodders. Sclerotium rolfsii cause both pre and post-emergence mortality of young seedlings besides inciting collar rot in adult plants is considered to be potential biotic limiting factor for cultivation of sunflower. Keeping this fact in view, few fungicides and bio-agents were tested as seed treatment and soil application to manage the collar rot of sunflower under screen house and field conditions. Results indicated that use of fungicides and bio-agents as seed and soil treatments significantly reduced the incidence of collar rot. Under screen house conditions, maximum disease control (75.15 %) was obtained by Vitavax power (carboxin + thiram ) @ 2g/kg seed followed by captan 50 WP @ 3g/kg (70.35%). &nbsp;Trichoderma harzianum @ 20g/kg soil application showed maximum control of the disease (40.62%) as compared to untreated control. Results of studies conducted under field conditions revealed that seed treatment with captan 50 WP @ 3g/kg seed was found most effective treatment in controlling the disease incidence (73.38 %). Among the different bio-agent evaluated, Pseudomonas fluorescensas &nbsp;as soil application gave maximum disease control (55.11 %) of collar rot of sunflower and also maximum seed yield</div>

Management of collar rot ( Sclerotium rolfsii Sacc.) in sunflower (Helianthus annuus L.)

Background: Collar rot of groundnut (Arachis hypogaea L.) caused by Aspergillus niger is a significant constraint in groundnut cultivation and responsible for huge economic losses in India including Rajasthan. 
 
Methods: By surveying of eight major groundnut growing districts of Rajasthan, India, one representative Aspergillus niger isolate from each district was established (ANBK-01= Bikaner, ANCH-02= Churu, ANDA-03= Dausa, ANJP-04= Jaipur, ANJL-05= Jalore, ANJD-06= Jodhpur, ANNG-07= Nagaur and ANSK-08= Sikar) for studying variability in the pathogen as well as to know the response of groundnut varieties to the highly virulent isolate. The colony and spore characteristics were observed for cultural and morphological variability. For resistance response to the disease, ten varieties (M-13, RG-633-9, RG-382, Girnar-2, RG-604, RG-578, Gajraj 10, RG-510, RG-632-1 and RG-644) were evaluated in the field for two consecutive years against a highly virulent Aspergillus niger (ANJP-04) isolate.&nbsp; 
 
Result: Our investigations cleared that all the isolates were showed cultural and morphological variability such as shape, colour and size of colony and size of conidia, conidiophores and columella. Isolate (ANJP-04) collected from Khejroli village of Chomu tehsil in Jaipur district showed maximum mycelial growth, conidia diameter, length and diameter of conidiophores and length and diameter of columella, early sporulation and found most virulent as it produced higher disease incidence (54.43%). Ten released varieties of groundnut in the field conditions, revealed that none of the variety was found completely free from the disease whereas RG-644, M-13 and RG-510 were found resistant while RG-604, Girnar-2, Gajraj-10 and RG-632-1 were found moderately resistant and rest were found susceptible to highly susceptible to the disease. Conclusively, it can be finalized that famers may cultivate these resistant varieties in areas where collar rot is a severe constraint. The conclusion of this study can also be utilized to screen varieties/genotypes of groundnut against highly virulent isolate for sustainability of breeding material to the disease effectively.

Variability and Virulence Analysis of Aspergillus niger Isolates Causing Collar Rot of Groundnut

Background: The chickpea, scientifically known as Cicer arietinum L., is a significant legume crop that serves as a valuable source of vegetable protein. The chickpea crop is susceptible to various pests and illnesses. Collar rot, induced by the fungal pathogen Sclerotium rolfsii, is a highly significant and extremely damaging disease that affects chickpea crops. The disease causes seedling mortality ranging from 54.7 to 95 per cent and field conditions result in yield decrease ranging from 22 to 50 per cent. The present study aimed to investigate the effectiveness of using a combination of fungicides, bio-agents and organic amendments for the management of collar rot in chickpea. 
 
Methods: The investigations were conducted in the Rabi seasons of 2019-20 and 2020-21. The experiments involved the integration of fungicides, fungal biocontrol agents (Trichoderma spp.), FYM and Vermicompost to control Collar rot disease in Chickpea caused by S. rolfsii. Six indigenous fungal antagonists (Trichoderma spp.) were assessed in a laboratory setting against S. rolfsii using both dual culture and non-volatile (culture filtrate) methods. The efficacy of the fungicides was assessed using the poison food technique. Nine fungicides were assessed in a laboratory setting to determine their effectiveness against a pathogen and Trichoderma harzianum-2. The fungicides were tested at four different concentrations: 50, 100, 500 and 1000 ppm. The goal was to identify fungicides that are extremely toxic to S. rolfsii at lower concentrations, while being less harmful to the bioagent Trichoderma spp. Pot culture studies were conducted using a completely randomised design (CRD), while field experiments were conducted using a randomised block design (RBD). 
 
Result: Trichoderma harzianum-2 (TH-2) was found to be highly efficient against the pathogen. It reduced the growth of the pathogen by 75.18% in the dual culture technique and by 61.85% in the culture filtrate approach. Among the nine fungicides tested, four of them, specifically propineb, mancozeb, captan 70% + hexaconazole 5% WP and penflufen 13.28% w/w + trifloxystrobin, showed lower inhibitory effects on Trichoderma harzianum at doses ranging from 50 to 1000 ppm. The treatment that resulted in the highest seed germination rate (100%) and the lowest occurrence of collar rot was the one where the seeds were treated with captan 70% + hexaconazole 5% WP and the soil was supplemented with Trichoderma harzianum through vermicompost application.

Combined Application of Bio-agents and Novel Fungicides for Management of Collar Rot of Chickpea&nbsp;

Background: Collar rot of chickpea infected by Sclerotium rolfsii is considered one of the major biotic factors for low productivity in chickpea. The present study was conducted to determine twenty nine isolates of collar rot were characterized for their Morphological, Pathogenic and Molecular variability. 
 
Methods: Twenty nine collar rot infected chickpea plant were collected from different places of Bundelkhand region of Uttar Pradesh. Pathogen was isolated from collar rot infected sample using PDA media followed by morphological, pathogenic and molecular variability studies from all isolates. Type of growth rate, mycelia colour, sclerotia size, sclerotial pattern, test weight of isolates was recorded by observing cultural plate after complete growth of mycelium. Pathogenicity test were done to check the aggressiveness of isolates in three varieties of chickpea. The isolated fungal DNA was amplified with specific primer pair, the quality and quantity of DNA was checked using gel electrophoresis and UV trasnliminator. 
 
Result: A morphological evaluation of isolates showed notable differences in identification characteristics, including colony size and sclerotial properties like count, test weight, dimensions and form on PDA media. Among the all isolates SRC 25 and SRC 28 considered as most virulent causes highest disease incidence in all selected chickpea variety under greenhouse experiments. RAPD analysis revealed distinct banding patterns, with PIC values between 0.59 and 0.89. The highest genetic similarity was observed between SRC-11 and SRC-29.

Morpho-pathogenic and Molecular Variability of Chickpea Collar Rot in Bundelkhand Region of Uttar Pradesh, India

<div>Background:&nbsp;Collar rot is an important disease of lentil in India and causes significant yield loss annually. Considering the recent focus on the development and use of environmentally feasible management strategies, the objectives of the study was to identify resistant sources and evaluation of native antagonists as well as plant growth promoting rhizobacteria (PGPRs) in yield improvement and disease management of lentil.&nbsp; 
 
Methods:&nbsp;Eleven popular lentil varieties were screened for resistance/susceptibility reaction against collar rot in vivo. The efficacy of two bacterial and fungal biocontrol agents (BCAs) was tested against a virulent isolate of Sclerotium rolfsii. Four PGPRs were also evaluated to study their influence on the growth parameters as well as their ability to manage S. rolfsii. 
 
Result:&nbsp;Three genotypes were found to be tolerant, four genotypes were moderately susceptible, while four genotypes were highly susceptible. Among the BCAs, the highest average inhibition % was observed in treatment with Bacillus sp. Among the PGPR treatments, Rhizobium in combination with phosphate solubilizing bacteria and Trichoderma or Bacillus was the most effective in controlling the collar rot when used as seed treatment and hence can be used for disease management.</div>

​​Eco-friendly Management of Collar Rot of Lentil by Introduced Native Rhizobacterial Candidates

Background: The devastating soil-borne chickpea disease known as collar rot, which is caused by Sclerotium rolfsii, results in significant yield losses globally, especially in Uttar Pradesh, India, where seedling mortality can range from 55% to 95%. Numerous environmental conditions, like as soil type, pH and sowing time, affect the frequency and severity of collar rot. Developing successful management strategies requires an understanding of the connection between these factors and the onset of disease. 
 
Methods: The study was carried out under controlled net-house circumstances throughout the 2022 rabi season (October-March). Four soil types typical of the Bundelkhand region (red, black, light brown and yellow) were tested. Chickpea plants were cultivated in these soils with variable pH values and two sowing dates (15-Nov and 15-Dec). Collar rot disease incidence and plant growth indicators such as shoot and root length were monitored throughout the growing season. Several chickpea cultivars, including L550, were assessed for sensitivity to collar rot. 
 
Result: The findings revealed that yellow soil had the lowest collar rot incidence (36.66%) and greatly increased plant growth, with an average shoot length of 38.24 cm and root length of 24.22 cm. In contrast, dark soil had the highest disease incidence (66.02%) and the lowest plant growth. Sowing timing had a significant impact on disease occurrence, with early sowing (15-Nov) having a greater incidence (21.37%) than late sowing (15-Dec) (11.19%). L550 was determined to be the most vulnerable to collar rot of all the cultivars studied. These findings emphasize the need of using optimal soil types and sowing timings to effectively minimize collar rot. 
&nbsp;

Impact of Soil Types and Sowing Times on Collar Rot of Chickpea Caused by Sclerotium rolfsii in Bundelkhand Region of U.P.

Background: Groundnut is an economically important edible oilseed crop. Groundnut suffers from seed, soil and foliar diseases. Among the groundnut diseases, collar rot is one of the economically important diseases. Collar rot is damaged regularly due to its seed and soil-borne nature. This disease is prevalent in almost all groundnut-growing states. Collar rot disease of groundnut is one of the most serious, destructive diseases and yield losses range from 13 to 52% and can be as high as 93.6% in some areas. Being mainly a soil-inhabiting pathogen, many environmental and soil factors are responsible for disease development. 
 
Methods: Field experiment was conducted for four years to find out effective control of collar rot of groundnut. Eight treatments including fungicides/bio agents along with control were laid in randomized block design with three replications. Efficacy of deep summer ploughing with mould board plough+Seed treatment with Tebuconazole followed by PGPR+Soil application of Trichoderma enriched in 250 kg FYM/ha at 35 and 80 DAS along with farmer practices as well as control was tested at ARS, Bikaner in RBD design during kharif season from 2017 to 2020 for management of collar rot diseases of groundnut.&nbsp; 
 
Result: The result of experiment revealed that deep summer ploughing with mould board plough+Soil application of Trichoderma @ 4 kg/ ha enriched in 250 kg FYM/ha+Seed treatment with Tebuconazole 2 DS @ 1.5 g/kg of seed followed by seed treatment with PGPR @ 625 g/ha of seed+Soil application of Trichoderma @ 4 kg/ha enriched in 250 kg FYM/ha at 35 and 80 DAS (T4) gave maximum germination (93.00%), minimum collar rot incidence (6.17%) and highest pod yield (4066.3 kg/ha) followed by deep summer ploughing with mould board plough+Seed treatment with Tebuconazole 2DS 1.5 g/kg seed followed by PGPR @ 625 g/ha of seed+Soil application of Trichoderma @ 4 kg/ ha enriched in 250 kg FYM/ha at 35 and 80 DAS (T1) where germination (89.30%), collar rot (7.04%) and with pod yield (3661.9 kg/ha). All the treatment significantly were superior as compared to control, where minimum germination (82.00), maximum collar rot incidence (15.59 %) and minimum pod yield (2125.1 kg/ha) were recorded. As regard to ICBR, in different treatments, maximum ICBR ratio (1:20.68) was recorded in treatment consisting (T4): Deep summer ploughing with mould board plough+Seed treatment with Tebuconazole 1.5 g/kg seeds+Soil application of Trichoderma @ 4 kg/ha enriched in 250 kg FYM/ha at 35 and 80 DAS followed by treatment (T1).

Management of Collar Rot Disease in Groundnut (Arachis hypogaea L.) Caused by Aspergillus niger in Rajasthan Through Bio-control Agents

Background: Groundnut (Arachis hypogaea L.) is one of the most important oilseed crops cultivated in India. However, its productivity is often reduced by several Seed and soil-borne pathogens that adversely affect germination, plant establishment and final yield. Collar rot caused by Aspergillus niger is a serious disease of groundnut, particularly during the early growth stages. To identify effective and eco-friendly management options, on-farm trials were conducted by Krishi Vigyan Kendra, Maulasar during Kharif seasons of 2021 and 2022 under farmers&rsquo; field conditions. All treatments resulted in a significantly higher seedling emergence rate (80.80%-96.67%) compared to the control group (70.12%). The maximum seedling emergence (96.67%) was observed with the combination of T. viride soil application and propiconazole seed treatment. Furthermore, among all evaluated fungicides and bioagents, this specific combination recorded the lowest disease incidence (11.81%) and the highest pod yield (24.99 q/ha). This was followed by the standalone propiconazole seed treatment, which exhibited a disease incidence of 15.25% and a pod yield of 21.95 q/ha. 
 
Methods: Different combinations of fungicides and biological control agents were evaluated. Treatments included soil application of Trichoderma viride 2.5 kg/ha, seed treatment with carbendazim 50 WP 2 g/kg seed, propiconazole 25 EC 2 ml/kg seed and T. viride 8 g/kg seed, as well as drenching with propiconazole 25 EC 500 ml/ha at 20 days after sowing. Observations were recorded on seedling emergence, disease incidence, pod yield, economic returns and benefit-cost ratio. 
 
Result: All disease-management treatments performed better than the untreated control. The combination of soil application of T. viride (2.5 kg ha-1) and seed treatment with propiconazole (2 ml kg-1&nbsp;seed) produced the best results, recording the highest seedling emergence (96.67%), lowest collar rot incidence (11.81%) and maximum pod yield (24.99 q ha-1). Seed treatment with propiconazole alone was the next most effective treatment, resulting in lower disease incidence and improved yield compared with other treatments. The study demonstrated that integrating biological and chemical approaches can effectively suppress collar rot and enhance groundnut productivity.

Efficacy of Biorational Approaches in Managing Collar rot Disease of Groundnut Caused by Aspergillus niger

<div>Sclerotium rolfsii is a soil borne fast spreading fungal pathogen that causes collar rot in chickpea. The variability among the pathogen isolates have made difficult to design efficient management practices and necessitates for a comprehensive study to know its diversity. The present study was planned to study the genetic diversity among the isolates of S. rolfsii collected from chickpea growing regions of Kurnool and Ananthapur districts of Andhra Pradesh at morphological and molecular level. The morphological characterization of isolates on PDA indicated that the isolates, CSR 14, CSR 18 and CSR 20, were fast growing and the overall growth i.e., sclerotia formation in terms of number, size and days to formation, was also faster. These isolates took only 4 days for production of sclerotial bodies. A total of 254 reproducible and scorable polymorphic bands ranging from 200 to 2000 bp were observed with twenty nine RAPD primers. The RAPD banding pattern reflected the presence of greater variability among the isolates and grouped the isolates into two clusters. The isolates, CSR 18 and 20, formed the cluster II revealing their distantness from other isolates at molecular level. The isolate, CSR 14, formed a separate sub cluster in the cluster I indicating its distant association with other isolates of this cluster.</div>