Symptoms Of Collar Rot Research Articles

Controlling Soil-Borne Fungus Aspergillus niger in Groundnut By Optimizing The Function of Isolated Bacillus Bacteria

Collar rot is a devastating disease caused by the soil-borne pathogen Aspergillus niger that greatly affects groundnut production worldwide. The long-term persistence of the fungus in the soil can reduce the effectiveness of synthetic fungicides. Recently, significant attention has been raised to the use of the biological control method such as the application of antagonistic microorganisms, which potentially decline the number of spores and eradicated A. niger from the soil. In the present study, three Bacillus strains (Bacillus siamensis 101, B. siamensis 112 and B. velezensis 137) isolated from the rhizosphere soil of groundnut cultivation farms were found to inhibit the growth of A. niger mycelia by 53.6% to 60.8% in vitro. In pot experiments, the supplementation of this mixture of three bacterial strains (namely BAZ04) strongly reduced the collar rot symptoms of groundnut with a biocontrol efficacy of 100% compared to nil (no treatment). Field trials demonstrated the efficiency of BAZ04 in controlling collar rot disease, which increased the yield by 20.5–22.7% compared to the untreated plots. These results suggest that BAZ04 is a potential biocontrol agent for collar rot disease.

Disease prevalence, incidence, morphological and molecular characterisation of Lasiodiplodia pseudotheobromae causing collar rot disease on peanut plants in Turkey

AbstractPeanut (Arachis hypogaea L.) holds significant commercial and dietary importance as a major source of edible oil and protein in Turkey. Stem, collar or root rot, caused by several fungal disease agent, are serious soil-borne diseases of peanut. Accurate and precise identification of the disease agent provides fundamental and precise information for integrated plant management. During the period from June to September 2021, symptoms consistent with collar rot disease, including dark-brown stem rot, chlorotic leaves, wilting, and eventual whole plant death, were observed on peanut plants cultivated in the different districts of Osmaniye Province of Turkey. The disease incidence ranged from 8.0 to 45.0% in the inspected fields with an average of 3.4% overall. Twenty-four single-spore representative isolates were obtained from surface-disinfected symptomatic tissues. Morphological characteristics of fungal mycelium, conidial and pycnidial structures on potato sucrose agar (PSA) and water agar (WA) closely resembled those described for Lasiodiplodia spp. All isolates caused typical collar rot symptoms upon artificial inoculation of peanut seedlings. Morphological identification of Lasiodiplodia spp. isolates was corroborated by MALDI-TOF and molecular analyses utilizing sequences from the internal transcribed spacer (ITS), β-tubulin 2 (tub2) and translation elongation factor-1 alpha (TEF1-α) loci. Phylogenetic analysis confirmed that the representative fungal isolates (MKUBK-B1 and MKUBK-K22) belong to Lasiodiplodia pseudotheobromae. To the best of our knowledge, this is the first report of L. pseudotheobromae infecting peanut plants in Turkey. This work is expected to contribute to previously limited knowledge regarding the host range, incidence and prevalence of L. pseudotheobromae as a soilborne pathogen of peanuts. Due to the potential destructiveness and broad host range of this pathogen, it is essential to develop new strategies to establish more reliable, environmentally sustainable, and cost-effective management approaches for this disease.

Diversity Studies of Sclerotium rolfsii Sacc. Isolates Associated with Collar Rot of Soybean Through Molecular and Biochemical Approaches

Background: Sclerotium rolfsii Sacc. is one of the potential soil-borne plant pathogens due to its significant loss in terms of yield and quality in several crop plants. In soybean the pathogen is associated with collar rot disease. Methods: Sixteen samples which were showing collar rot symptoms were collected from different soybean growing regions of the country and were subjected for isolation and purification. Molecular detection was carried out using ITS1/4 primers followed by phylogenetic analysis was performed using the MEGA 11 bioinformatics tool. Further, the biochemical test was made for oxalic acid production to determine the variability across the isolate. Result: DNA was amplified for ITS rDNA region at 650-700 bp in all the sixteen isolates. BLAST detection of nucleotide sequence of sixteen isolates framed mainly into two distinct phylogenetic clusters. Cluster B consisted of two isolates (MPSe 1 and MHSa 3) whereas, Cluster A contains the remaining fourteen isolates. There was a variation with respect to oxalic acid production among the isolates which was in the rage of 1.15 to 2.23 mg/ml.

Isolation and Molecular Characterization of Collar Rot Causing Pathogen Aspergillus niger on Groundnut in Rajasthan, India

Groundnut, a major pulse crop also grown as an oil seed over 90 countries worldwide, is important to the Indian economy. The states of Andhra Pradesh, Gujarat, Rajasthan and Tamil Nadu are the main producers of groundnut. In 2021, disease incidence with symptoms similar to collar rot was reported from Jaipur district of Rajasthan. The fungal strain was isolated from the collar region of susceptible groundnut variety TAG-24. White colonies with mycelia were observed in 3-4 days which eventually turned dark brown in color. Pathogenicity tests were performed on healthy groundnut and collar rot symptoms developed within 7-8 days of inoculation. Sequencing of PCR products amplified with the18S rRNA (NS1F-NS8R) and ITS (NS1F-ITS4R) primers indicated 99.4% and 100% identity respectively with a reference strain of Aspergillus niger CBS 554.65 (ATCC 16888) in the NCBI-Genebank database. Based on the morphological and molecular characteristics, the fungal pathogen was identified as Aspergillus niger and submitted to Gene Bank with the accession nos. ON954789 and OQ653131. The the culture is submitted to NCMR-NCCS (accession number MCC 9892).

Phytophthora alticola and P. boodjera associated with decline of young Eucalyptus smithii trees in Uruguay

AbstractEucalyptus production mainly destined to cellulose pulp production has expanded strongly in the last 30 years in Uruguay. Eucalyptus smithii has recently emerged as a promising species for cellulose pulp production. However, an average of 40% of young trees die during the first and second summer of post‐planting. In this study, 32 Phytophthora isolates were obtained from 132 E. smithii young trees with root and collar rot symptoms, confirming the association of Phytophthora to E. smithii decline. Based on phylogenetic analysis of ITS, TUB2, cox1 and HSP90 gene regions and phenotypical characteristics, two species belonging to the genera Phytophthora clade 4 were identified, P. alticola (96%) and P. boodjera (4%). Tested isolates of both species significantly reduced both shoot and root dry weights of inoculated E. smithii seedlings compared to control plants. To our best knowledge, this is the first time that P. alticola and P. boodjera are recovered from young symptomatic E. smithii trees in commercial plantations as well as the first time these species are found in the Americas.

A report of collar rot disease of Sugandh mantri (Homalomena aromatica) caused by Sclerotium delphinii in West Tripura state of India

During the year 2018–19, collar rot symptoms on Sugandh mantri plants were observed in fields in Agartala district of West Tripura state of India with a disease incidence of 20%. In the early stages of disease development, typical collar rot symptoms exhibited were dark brown necrotic lesions on the stem base. Later, the affected plants completely rotted and died. The diseased samples plated on PDA medium showed abundant, fluffy, dense white mycelia with reddish brown spherical sclerotia matching with the morphology of Sclerotium delphinii. The internal transcribed spacer (ITS) region of rDNA of the fungus was amplified and sequenced. The sequences revealed 99–100% identity with Sclerotium delphinii. The Koch's postulates were performed on three-month-old Sugandh mantri plants to confirm the pathogenicity of the isolated fungus. To the best of our knowledge, this is the first report of Sclerotium delphinii causing collar rot disease on Sugandh mantri plants in India.

First Report of Collar Rot Caused by Sclerotinia sclerotiorum on Sesame (Sesamum indicum) in Mexico.

Sesame (Sesamum indicum L.: Pedaliaceae) is the second most cultivated oilseed in Mexico with 80,000 ha per year. The seeds of this crop are used as a condiment, for the extraction of oil, and its medicinal properties. In October 2020, collar rot symptoms were observed in six sesame fields (SOPC-9539 TD variety) located in the Carrizo Valley (26°15'33.1"N; 109°01'37.9"W), El Fuerte, Sinaloa, México. Initially, small brown spots in the basal stem of the infected plants were observed. At advanced stages of the disease, the circumference of stem was necrotic with the presence of white mycelium that extends to the roots. Infected plants were showing symptoms of yellowing, wilting, and finally death. Disease incidence was estimated at 15%, counting the total of diseased plants in five counts done in arbitrary quadrants within the sesame fields. For fungal isolation, stem sections from the symptomatic basal stem were surface disinfected with 1.5% sodium hypochlorite for 2 min, then triple rinsed with sterile distilled water. The tissue sections were dried on sterile blotting paper and plated in Petri dishes with potato dextrose agar (PDA) culture medium. The plates were incubated at 28ºC in darkness for 48 h. Sclerotinia-like colonies were consistently isolated and four isolates from different locations were purified by the hyphal-tip method. Fungal colonies were formed of compact white mycelium, with the formation of sclerotia on the margin of the plate 6 days after inoculating PDA cultures. Sclerotia averaged 3.1 mm in diameter and 0.024 g. One isolate was deposited in the Culture Collection of Phytopathogenic Fungi of the Faculty of Agriculture of Fuerte Valley at the Sinaloa Autonomous University under Accession no. FAVF654. To confirm identification, genomic DNA was extracted from one isolate, and the internal transcribed spacer (ITS) region was amplified by PCR and sequenced directly using the primer pair ITS5/ITS4 (White et al. 1990). The resulting consensus sequence was deposited in GenBank under accession no. ON401416. BLASTn alignments in GenBank showed 100% identity of our sequence with the sequence of the type strain of Sclerotinia sclerotiorum ATCC 46762 (accession no. JX648201). Pathogenicity of the fungus was demonstrated by inoculating healthy sesame plants (Dormilón and SOPC-9539 TD ies), germinated in plastic pots with sterile substrate. Plants were inoculated with the FAVF654 isolate by applying 3 sclerotia at the base of each of the 12 plants. Twelve plants were left uninoculated, which served as controls. All the inoculated plants, of both varieties, developed the characteristic symptoms of the disease 7 days after inoculation, while the control plants remained symptomless. The pathogenicity test was performed twice with the same result. The fungus was reisolated from all the inoculated plants, thus fulfilling Koch's postulates. Sclerotinia sclerotiorum has been reported on sesame plants in Bulgaria and Korea (Farr and Rossman, 2022). To our knowledge, this is the first report of Sclerotinia sclerotiorum causing collar rot in sesame plants in Mexico and the Americas. This disease considerably reduces the yield of sesame; therefore it is necessary to develop effective disease-management strategies.

Studies on the biological methods for the management of Coffee (Coffea arabica L.) collar rot (Rhiozoctonia solani khun) by Coffee bio-capsules

Coffee is an important plantation crop in India. Arabica and Robusta coffee are susceptible to fungal disease. Coffee plants propagated through seeds. Rhiozoctonia solani khun is known to cause collar rot/damping off of coffee seedlings in the nursery beds and lead to 10-25 % mortality of seedlings under favourable conditions. For effective management of this disease by bio capsule methods the present study was carried out, ten Rhiozoctonia solani khun isolates were collected from different regions. The pathogenicity effect to produce collar rot symptoms showed that R.s tn 4 is high virulent compared to other isolates during the period of April- June were noticed. In case of bio control agents such as Bacillus subtilis (58.65%) inhibition found to be maximum mean per cent inhibition compared to untreated control (70.50%)

First Report of Sclerotium rolfsii Causing Collar Rot of Guar (Cyamopsis tetragonoloba) in Mexico.

Cyamopsis tetragonoloba (Fabaceae), also known as guar or cluster bean, is an annual legume grown mainly for industrial purposes and also as an ingredient for animal feed. In October 2021, collar rot symptoms were observed in five guar fields located in Guasave, Sinaloa, Mexico. Abundant white mycelium, and later brown and small sclerotia were observed at the base of the stems. Diseased plants showed reduced growth, wilting, and drying of the entire plant. Disease incidence ranged from 15 to 40%. Samples were collected from each field at two phenological stages (vegetative and reproductive). For fungal isolation, symptomatic stems pieces were surface sterilized with 2% sodium hypochlorite for 2 min, rinsed in sterilized distilled water two times, placed on PDA medium and incubated at 28°C in darkness for 3 days. Sclerotium-like colonies were consistently obtained and five isolates from five different fields were purified by the hyphal-tip method. Fungal colonies were white, cottony, and often forming fans. Sclerotia (1 to 2 mm diameter) were white at first and then gradually turned dark brown. Microscopic examination showed septate hyphae with some cells having clamp connections. A representative isolate was deposited in the Culture Collection of Phytopathogenic Fungi of the Faculty of Agriculture of Fuerte Valley at the Sinaloa Autonomous University under Accession no. FAVF647. For molecular identification, genomic DNA was extracted, and the internal transcribed spacer (ITS) region was amplified by PCR and sequenced using the primer pair ITS5/ITS4 (White et al. 1990). The sequence was deposited in GenBank (accession no. OM510466). BLASTn searches in GenBank showed 99.21 to 100% identity with the available sequences of Sclerotium rolfsii (accession nos. MK926446, MH854711, and KY175225). A phylogenetic analysis using the maximum Likelihood method placed isolate FAVF647 in the same clade as S. rolfsii. Pathogenicity tests were performed by inoculating 10 healthy guar seedlings (15-day-old) grown in pots. Four sclerotia were directly placed on the stem base of each plant. Five uninoculated guar seedlings were used as control. All plants were placed in a moist chamber at 25°C with a 12-h photoperiod for 2 days. Collar rot symptoms appeared on inoculated plants after 3 days, whereas control plants remained symptomless. Pathogenicity test was performed twice with similar results. The fungus was reisolated from the artificially inoculated plants, thus fulfilling Koch's postulates. Sclerotium rolfsii has been reported on guar plants in Australia, Brazil, Fiji, India, and the United States (Farr and Rossman 2022). To our knowledge, this is the first report of Sclerotium rolfsii causing collar rot of guar in Mexico. The disease is very common in guar fields in Sinaloa, Mexico, therefore additional studies are needed to develop effective disease-management strategies.

Phytophthora Root and Crown Rot of Plum

In this study was investigated the Phytophthora spp., effects on plum trees in Skopelos island, Greece. Trees impacted by Phytophthora showed collar rot symptoms (below ground), crown rot and reddishbrown discoloration of the bark and poor growth with sparse, off-color foliage (above ground). Results showed that improve soil drainage techniques and application of fosetyl-Al when new leaves are hardening proved a good strategy to encourage

Southern Blight on Macleaya microcarpa Caused by Sclerotium rolfsii in China

Macleaya microcarpa (Maxim.) Fedde is a perennial herb belonging to the family Papaveraceae. This plant and the better-known species M. cordata (Willd.) R. Br. are native to central China and now planted worldwide for medicinal purposes (Qing et al. 2015). In August 2018, M. microcarpa in the Chinese herbal medicine planting base (approximately 4.3 ha) of Hunan Agriculture University in Changsha City, Hunan Province, showed what seemed to be a soilborne disease, in which approximately 25% of the plants were affected. The characteristic symptoms consisted of rotting, wilting, and blighting. Infected plants gradually withered, and white mycelial mats and sclerotia appeared on the surface of roots and stems at the soil line. Five sclerotia collected from three infected plants were surface disinfested in 0.5% NaOCl for 30 s, followed by 75% alcohol for 10 s, rinsed in sterile water three times, air dried, plated onto potato dextrose agar (PDA) with one sclerotium per dish, and incubated at 30°C in the dark. After 5 days, the aerial white mycelium usually formed many narrow hyphal strands, 4 to 9 μm wide. The white mycelium formed typical clamp connections. Numerous globoid sclerotia formed on PDA after 15 days of growth. The sclerotia (1 to 3 mm in diameter) were white at first and then gradually turned dark brown. Isolates were identified as Sclerotium rolfsii on the basis of mycelial characteristics, color, and sclerotia. Sequence analyses were conducted on sclerotia by extracting fungal DNA with the DNAsecure Plant Kit (Tiangen Biotech, China). To confirm the isolate identification, part of the elongation factor 1-alpha (EF1-α) gene and the complete internal transcribed spacer (ITS) region of the fungus were amplified using the primers EF595F/EF1160R (Wendland and Kohe 1997) and ITS1/ITS4 (White et al. 1990), respectively. BLAST searches revealed that the EF1-α sequence (MK275299) had 99% sequence identity to S. rolfsii (GenBank accession nos. JN790645.1, KM521757.1, and JF267794.1). The ITS sequence (MK275300) had 96% identity to S. rolfsii (GenBank accession nos. KU885934.1, KT428156.1, and MH858139.1). To fulfill Koch’s postulates, five healthy 60-day-old M. microcarpa seedlings were inoculated with sclerotia obtained from a 15-day-old culture. The seedlings were grown in greenhouse pots with a sterilized mixture of peat moss and vermiculite (3:1). Dry sclerotia were placed directly in the wounds made with a sterile blade on the root (three sclerotia per plant). Five control plants were inoculated with clean PDA plugs. All plants were packed in plastic bags that had been sprayed with water to maintain high humidity and kept at approximately 30°C in the laboratory. Five days postinoculation, the inoculated M. microcarpa seedlings presented wilt and collar rot symptoms, whereas those not inoculated were symptomless. S. rolfsii could be reisolated from the infected plants. The experiment was repeated with similar results. To our knowledge, this is the first report of southern blight caused by S. rolfsii on M. microcarpa in China. Southern blight caused by S. rolfsii is a serious soilborne disease and able to cause plant death. Understanding its etiology may help to the control of this plant fungal pathogen, thus reducing economic losses.

Identification of Phytophthora capsici causing collar rot in hot peppers in Trinidad

Hot pepper (Capsicum chinense Jacq.) is an economically important commercial crop cultivated in Trinidad for domestic consumption and for export in its fresh and processed forms. Collar rot and wilting symptoms have been observed in major hot pepper producing areas of Trinidad over several years, resulting in severe crop losses. Isolations were made from infected plants using corn meal agar (CMA) amended with antibiotics. The isolated organism was identified as Phytophthora capsici based on morphological and microscopic observations. Inoculation of zoospores of P. capsici onto healthy seedlings confirmed the typical expression of symptoms of collar rot and wilting in hot peppers under greenhouse conditions. PCR amplification and nucleotide sequencing of the internal transcribed spacer (ITS) region of rDNA using the primers ITS4 and ITS6 and of the mitochondrial cytochrome c oxidase gene using primers FMPhy-8b and FMPhy-10b confirmed the pathogen as P. capsici. To the best of our knowledge, this is the first report identifying and confirming P. capsici affecting hot peppers in Trinidad.

Macrophomina phaseolina – Meloidogyne javanica disease complex in balsam (Impatiens balsamina): a new report

Balsam seedlings were inoculated with root-knot nematode Meloidogyne javanica Race-2 and Macrophomina phaseolina either individually or concomitantly, as well as sequentially with an interval of 15 days between the nematode or fungal inoculations to determine whether the interaction was concomitant or sequential. The greater reduction in plant growth characters was observed in the plants inoculated with M. javanica and M. phaseolina, either concomitantly or sequentially as compared to their individual inoculation. However, the highest reduction in plant growth characters were recorded in the plants inoculated with M. javanica Race-2 15 days prior to M. phaseolina followed by concomitant-inoculated M. javanica Race-2 and M. phaseolina, and M. phaseolina 15 days prior to M. javanica. The number of galls/root system and the reproduction factor of the root-knot nematode was reduced in the presence of root-rot fungus. The intensity of root-rot caused by M. phaseolina increased in the presence of root-knot nematode M. javanica as compared to when M. phaseolina was inoculated individually. Moreover, stem and collar-rot symptoms caused by M. phaseolina appeared only in the presence of root-knot nematode.

Recovery, pathogenicity and molecular sequencing of Calonectria ilicicola which causes collar rot on Carica papaya in Australia

Symptoms of collar rot were observed on 3-month-old papaya plants cv. RB1. The pathogen was identified as Calonectria ilicicola based on disease symptoms, fungal morphology, pathogenicity and ITS sequencing.

Influence of internal seedborne Fusarium semitectum on cotton seedlings

Fusarium semitectum was found to be the major seed colonizing fungus in the commercial acid delinted cotton (Gossypium hirsutum) seed lots. There was no correlation, however, between its incidence and seedling emergence and disease symptoms on the emerged seedlings in autoclaved sand. Inoculation technique simulating internally seedborne nature of the fungus showed that the observed non-correlation might be related to the threshold level of seed coat colonization. The internally seedborne inoculum besides reducing seedling emergence, incited an array of symptoms on the emerged seedlings, which ranged from negative geotropism, leaf tearing, collar rot leading to dry root rot and seedling mortality. The dry root rot continued to develop on the plants surviving the seedling phase. The collar rot symptoms can be confused with those caused by Rhizoctonia solani.

Collar rot of Chlorophytum borivilianum caused by Corticium rolfsii: a new disease

A new disease of Chlorophytum borivilianum, characterized by symptoms of collar rot, has been observed in experimental farms of the National Botanical Research Institute, Lucknow, India. The pathogen has been isolated and identified as Corticium rolfsii.

First Report of Phytophthora Root and Collar Rot of Alder in Hungary.

In June 1999, a disease associated with mortality of Alnus glutinosa, was observed in a 12- to 18-year-old peatland plantation in northwest Hungary. The root and collar rot symptoms were similar to those caused by Phytophthora cambivora in tree species other than alders. Nine isolations were made from diseased roots and soil samples using the Rhododendron leaf baiting method. Three isolates recovered from two sites, approximately 2 km apart, exhibited similar growth and morphology in vitro and were pathogenic to 2-year-old trees of A. glutinosa following inoculation of root collars. All three isolates had amphigynous long, two-celled antheridia. The mean diameter of oogonia ranged from 39.5 to 64.6 μm. They also produced nonpapillate, ellipsoid, non-caducous sporangia 26.9 to 50.5 μm long and 19.3 to 38.5 μm wide with broad exit pores in soil filtrate. These characteristics were similar to those reported for Phytophthora on alder from elsewhere in Europe and for P. cambivora that is not a pathogen of alder (1,2). However, Hungarian isolates from alder, in contrast to P. cambivora, were homothallic like previously recorded isolates from alder, formed nonornamented oogonia and developed colonies at lower optimum (approximately 25°C) and maximum (approximately 30°C) temperatures on carrot agar. A comparison with Phytophthora from alder from other countries (courtesy of C. M. Brasier) showed that the Hungarian isolates have smooth-walled oogonia typical of Swedish isolates rather than the ornamented oogonia of U.K. isolates, but have the appressed, slightly woolly colony morphology like U.K. isolates rather than the fluffy growth found in Swedish isolates. Moreover, cellulose acetate electrophoresis of glucose-6-phosphate isomerase revealed one homodimer band in Hungarian isolates that was identical with that of the Swedish isolate from alder P876 and isolates P1010 and P1011 of P. cambivora (courtesy of C. M. Brasier). This band comigrated with the middle one of the five-banded U.K. standard isolate P772. Molecular evidence (2) indicates that the Phytophthora from alder with its unusual characteristics is not a species in the strict sense but comprises natural hybrids that may have originated in an interspecific hybridization event between a P. cambivora-like species and an unknown species similar to P. fragariae. On this basis, the Hungarian Phytophthora from alder might have evolved similarly. It remains to be determined whether the pathogen was introduced or has developed independently.