Rice False Smut Disease Research Articles

Rice false smut disease: An emerging threat to the paddy growers in Tamil Nadu

Rice false smut disease: An emerging threat to the paddy growers in Tamil Nadu

Sclerotia of rice false smut disease in Bangladesh

It is perceived that sclerotia of the pathogen, in addition to chlamydospores, play an important role in the epidemiology of rice false smut disease. The propagule has been identified only in five rice growing countries of the world, and never recorded in Bangladesh. This study was undertaken to identify the sclerotia, quantify their concentration on smut balls and estimate the time of its formation. Intensive field-by-field monitoring was conducted during 2014, 2015 and 2016 at experimental farm of the Bangladesh Rice Research Institute, Gazipur. After rigorous search, sclerotia of rice false smut pathogen was identified on the 14th of December 2014. The was observed in the later part of crop maturity during the ‘T. Aman’ season (early-November to mid-December) on olivaceous greenish-black smut balls, but not on orange smut ball. During the three years study, on average, 30.61±9.79% (± is 95%confidence interval) olivaceous greenish-black smut balls borne sclerotia, the average number being 1.63±0.09 per sclerotia-bearing ball. The ‘threshold temperature’ for sclerotia formation was estimated as above 11°C difference in day-night temperature. Consistence presence and high concentration of sclerotia in smut balls signify its role in the epidemiology of the disease in the agroecology of Bangladesh.

Eco-friendly management of false smut disease of rice incited by <i>Ustilaginoidea virens</i> through the application of <i>Trichoderma</i> spp

False smut disease of rice incited by Ustilaginoidea virens is an organ-specific pathogen that causes chalkiness of grain which leads to a reduction in 1000 grain test weight and yield. The dual culture assay results revealed that each Trichoderma isolates suppress the mean mycelial growth of U. virens under in-vitro conditions. Among the nine different Trichoderma isolates, 3 isolates were selected as effective isolates viz., TKM1, TKT9 and TTN5. Among these three effective isolates, maximum mycelial growth inhibition was recorded in the isolate TKM1 with 80.18 percentage reduction over control. The SEM photographs revealed that the hyphal round off in U. virens which is mainly due to the production of volatiles through direct antagonistic activity and competition through indirect antagonistic activity in which conidial adherence of T. harzianum over the surface of the mycelial mat of U. virens was observed. In 2020, the field experiment results revealed that the minimum disease severity was recorded when the Trichoderma isolate TKM1 was sprayed during booting stage with 4.61%, 50% PE stage with 17.91% and 100% PE with 21.86%. In 2021 the disease severity varied from 9.21% to 69.59%. The lowest disease severity was recorded in the plots sprayed with propiconazole fungicide with 9.21%. However, the disease severity recorded in fungicide treated plots were statistically on par with the Trichoderma isolate TKM1 treated plots at 50% PE spray with 10.60%. The disease severity recorded in the plots sprayed with TKM1 showed non-significant relationship with the fungicide treated plots which clearly revealed that the control efficacy of both TKM1 and Propiconazole treated plots were similar with each other. Among the Trichoderma treated plots the yield gain varied from 10.01% to17.20%. The yield gain was found to be 18.35% in fungicide treated plots. The yield and yield gain obtained by the effective isolate TKM1 (yield = 6405 kg/ha and yield gain = 17.20%) was statistically on par with propiconazole treated plots and significantly showed better yield and yield gain than the control plots. In 2021 among the Trichoderma treated plots the yield gain varied from 4.10% to 10.16%. The maximum yield gain was recorded in the fungicide treated plots (12.00%).

Antifungal mechanisms of silver nanoparticles on mycotoxin producing rice false smut fungus

Ustilaginoidea virens, which causes rice false smut disease, is a destructive filamentous fungal pathogen, attracting more attention to search for effective fungicides against U. virens. Here, the results showed that the inhibition of 2nm AgNPs on U. virens growth and virulence displayed concentration-dependent manner. Abnormalities of fungal morphology were observed upon exposure to AgNPs. RNA-sequencing (RNA-seq) analysis revealed that AgNPs treatment up-regulated 1185 genes and down-regulated 937 genes, which significantly overlapped with the methyltransferase UvKmt6-regulated genes. Furthermore, we found that AgNPs reduced the UvKmt6-mediated H3K27me3 modification, resulting in the up-regulation of ustilaginoidin biosynthetic genes The decrease of H3K27me3 level was associated with the inhibition of mycelial growth by AgNPs treatment. These results suggested that AgNPs are an effective nano-fungicide for the control of rice false smut disease, but when using AgNPs, it needs to be combined with mycotoxin-reducing fungicides to reduce the risk of toxin pollution.

Spatial Distribution Patterns for Identifying Risk Areas Associated with False Smut Disease of Rice in Southern India

False smut disease (FSD) of rice incited by Ustilaginoidea virens is an emerging threat to paddy cultivation worldwide. We investigated the spatial distribution of FSD in different paddy ecosystems of South Indian states, viz., Andhra Pradesh, Karnataka, Tamil Nadu, and Telangana, by considering the exploratory data from 111 sampling sites. Point pattern and surface interpolation analyses were carried out to identify the spatial patterns of FSD across the studied areas. The spatial clusters of FSD were confirmed by employing spatial autocorrelation and Ripley’s K function. Further, ordinary kriging (OK), indicator kriging (IK), and inverse distance weighting (IDW) were used to create spatial maps by predicting the values at unvisited locations. The agglomerative hierarchical cluster analysis using the average linkage method identified four main clusters of FSD. From the Local Moran’s I statistic, most of the areas of Andhra Pradesh and Tamil Nadu were clustered together (at I > 0), except the coastal and interior districts of Karnataka (at I < 0). Spatial patterns of FSD severity were determined by semi-variogram experimental models, and the spherical model was the best fit. Results from the interpolation technique, the potential FSD hot spots/risk areas were majorly identified in Tamil Nadu and a few traditional rice-growing ecosystems of Northern Karnataka. This is the first intensive study that attempted to understand the spatial patterns of FSD using geostatistical approaches in India. The findings from this study would help in setting up ecosystem-specific management strategies to reduce the spread of FSD in India.

Screening of Fungicides and Botanicals for Controlling False Smut of Rice

The present investigation was conducted in the field laboratory of the Department of Plant Pathology, Patuakhali Science and Technology University during August 2017 to December 2017 to evaluate the efficacy of botanicals viz., neem leaf extract, garlic clove extract, tulshi leaf extract and zinger rhizome extract at 10% concentration and fungicides viz., TALL 25EC, RAI 32.5 SC, TOWIN 50 WP, Syconazole 25SC and Y-Thane M-45 at 0.2% concentration to control rice false smut disease. The experiment was set up in a Randomized Complete Block Design (RCBD) with 3 replications. Among the treatments RAI 32.5 SC= Suspension concentrate and tulsi leaf extract performed better in respect of percent hill infection and it was 0.51%, 1.03%, 1.28% and 1.79% respectively at 85, 95, 105 and 115 days after transplanting (DAT). Result showed that the lowest percent plant and panicle infection at different days after transplanting were highest in the plot treated with RAI 32.5 SC followed by garlic extract. RAI 32.5 SC showed minimum percent infected grains which were 0.26%, 1.03% and 1.17% at 85, 105 and 115 DAT respectively and maximum 1.22%, 2.39% and 2.99% respectively, in the control plot at 85, 105, and 115 DAT. The highest thousand grain weight (114.6) and yield (4.790) were obtained in RAI 32.5 SC and the lowest thousand grain weight (108.3) and yield (3.587) harvested from the control plot.

Cultural, Molecular and Genetic Variability of Ustilaginoidea virens Causing Rice False Smut Disease

Rice false smut disease is caused by Ustilaginoidea virens, an ascomycetous fungi. Thirty isolates of U. virens showed well defined colonies on potato sucrose medium (PSA). The maximum colony diameter was found to be 85.68 mm with a growth rate of 2.85 mm in the UV23 isolate and the minimum colony diameter was found to be 10.14 mm with a growth rate of 0.33 mm, which was observed in the UV15 isolate. However, thirty isolates exhibit various cultural and morphological characteristics like colony color, growth pattern, elevation, and chlamydospore formation. In cluster analysis, two major groups (I) and (II) were formed. The first major group (I) contains UV15 isolates and the second major group (II) contains 29UV isolates. Furthermore, the division of group II includes subgroup IIa, which contains 22 isolates, and subgroup IIb, with 7 isolates. The PCR amplification was done with a species-specific primer which yielded products of 380 bp and 230 bp, respectively. The results of the phylogenetic tree analysis revealed that cluster I contained 5 isolates and cluster II contained 28 isoates from China and Japan. The MAT1-1-1 primer yielded a product of 250 bp that contains 18 isolates. Whereas the MAT1-2-1 primer yielded a product of 220 bp with 12 isolates. The nucleotide divergence analysis results revealed 7 polymorphic sites (s), 10 mutations (Eta), 0.76515 nucleotide diversity (k) and -2.13885 for the tajimas test value. Likewise, haplotype analysis revealed 10 haplotype(h)groups, with a haplotype diversity (hd) of 0.4773. With 24 isolates, hap-1 was the most common. Similarly, clear nucleotide variation was observed between Indian and Chinese isolates as well as Japanese ones. The genetic similarity coefficient matrix revealed that thirty Indian isolates showed maximum similarity (0.9). whereas the UV32 isolate showed 0.6, the UV31 isolate exhibited 0.5, and the UVA33 isolate had 0.4,.These results indicate a genetic variability between the Indian UV isolates and the isolates from China.

Survey and surveillance on rice false smut disease severity in Tamil Nadu and the influence of wind velocity on disease progression under field conditions

The false smut disease of rice incited by Ustilaginoidea virens is a major constraint on rice production. The main aim of the present study was to ascertain the false smut disease severity in both delta and non-delta districts of Tamil Nadu through survey and surveillance and assess the correlation between the disease severity and wind velocity for the past three years, 2019, 2020 and 2021. Moreover, the present study addressed the disease distribution pattern of false smut diseases under field conditions. The results obtained from survey results revealed that the maximum disease severity was recorded in Nagapattinam district (Nagapattinam block) with 27.45% and the minimum disease severity was recorded in the district Theni (Bodinayakanur block) with 8% in 2021. Similarly in 2019 and 2020 maximum disease severity was recorded in the following districts Thanjavur district (Orathanadu block) with 19.91% and Thanjavur district (Peravurani block) with 18.54% and the minimum disease severity was recorded in the following districts Madurai district (Madurai north block) with 4.78% and Madurai district (Usilampatti block) with 4.78% respectively. The obtained R2 values through regression analysis were 0.70, 0.79 and 0.76 in the following years, 2019, 2020 and 2021, respectively. Besides the relationship between the false smut disease development, the pattern wind direction was also assessed. By assessing the false smut disease distribution pattern under field conditions, more disease distribution was observed around the surrounding area of the paddy field as well as the diagonal path of the field which clearly revealed that wind direction influences the disease development.

Assessing the molecular variability in Ustilaginoidea virens, the rice false smut pathogen with ISSR markers

Rice false smut disease is gaining importance because of its impact on the grain yield and its toxin production ability. Fifty-eight isolates of Ustilaginoidea virens were collected from different rice-growing regions of India. DNA of U. virens was isolated by the CTAB method and fifty ISSR primers were screened for molecular variability studies. Twelve primers viz., UBC series 807, 808, 809, 810, 811, 812, 834, 835, 836, 840, 841, and 842 were selected to study the genetic variability. Different parameters of tested primers viz., heterozygosity (Hn), polymorphism information content (PIC), effective multiplex ratio (EMR), marker Index (MI), and resolving power (RP) were calculated. Primers UBC 812 and UBC 809 recorded maximum heterozygosity (Hn). The PIC values ranged from 0.10 to 0.27 and UBC 807 recorded the maximum value of 0.27. The EMR value varied from 6.75 to 24.0, Similarly, UBC 807 recorded the highest value of MI (24) and RP (8.55). A dendrogram was generated using the DARwin software (version 6.0.21A) based on the unweighted neighbor-joining cluster method. All the fifty-eight U. virens isolates were grouped into three major clusters. Clusters I and II had 21 and 35 U. virens isolates respectively. Cluster III had only two isolates. The isolates showed genetic variations and there was no specific grouping based on the geographical distance.

Status of false smut of rice in different districts of West Bengal

False smut of rice which was considered a minor disease of rice is presently spreading in most of the rice growing areas of the world causing reduction in yield and quality of the produce. West Bengal is the largest producer with largest area under rice in India. No survey on severity of rice false smut disease in West Bengal has been conducted. Therefore, in attempt to get the idea of false smut disease situation in the state, a survey was conducted in 31 blocks from 8 different districts of West Bengal during the year 2017 from the end of October to first week of December. Number of infected tillers per m2 and number of smut balls per panicle was observed during the survey. False smut symptom was observed in all the plains of West Bengal whereas in hilly areas of the state was found to have no incidence of the disease. During the survey average number of infected tillers ranged from 2.00 to 14.60 numbers of infected tillers / m2. Similarly average number of smutted ball / panicle ranged from 1.21 to 5.32 number of spore ball per panicle.

Culture condition and variation in the pathogenicity of Ustilagonoidea virens isolates causing false smut disease of rice

False smut of rice caused by Ustilagonoidea virens was previously considered a minor disease of rice or rather a sign of bumper harvest, hence the disease was also known by the name Lakshmi disease. However, the disease is gaining much importance at present and is reported to occur in most of the rice growing areas of world in moderate to severe forms. Rice which is cultivated throughout the year in West Bengal is also observed to produce the symptoms of the disease every year in varying degree of severity. Effect of light and different temperature on mycelial growth of Ustilagonoidea virens in BOD incubator was tested. It was found that temperature of 28oC and dark condition favors mycelial growth. Twelve different isolates of Ustilagonoidea virens collected from different districts of West Bengal were isolated in laboratory and tested for their variability in Pathogenicity using the susceptible rice variety Swarna (MTU 7029). 2 ml of inoculum suspension of each isolates were injected to rice plant at booting stage with three replications, whereas in control plants 2 ml of sterilized water was injected and percent grain infection was calculated and analyzed. All the inoculated plants were observed to produce typical false disease symptom with varying degree of severity indicating variation in pathogenicity among the isolates. Percent grain infection ranged from 1.461% to 7.936%. Isolate Uv5 from Alipudwar district was found to be significantly more virulent as compared to other isolates with 7.936% grain infection followed by isolate Uv4 (Jalpaiguri district) and Uv3(Nadia district)  with 5.050% and 4.557% grain infection respectively. Significantly lower infection was observed in isolate Uv9 collected from Coochbehar district with 1.461% grain infection followed by isolate Uv2 (North 24 Parganas district) and Uv12 (Hooghly district) with 1.912 and 3.279% grain infection.

Transcription Profiling of Rice Panicle in Response to Crude Toxin Extract of Ustilaginoidea virens.

Ustilaginoidea virens infects rice, causing rice false smut disease and reduced yields. During its growth, U. virens can also produce some toxins but less is known about the response mechanisms of the plant to U. virens toxins. U. virens toxins can inhibit the accumulation of total sugar in rice panicles. We used RNA sequencing to analyze the differential expression profile induced by infiltrating crude toxins into early growth-stage rice panicles. We compared the transcriptomes of the control and crude toxin-treated rice panicles and determined variable transcriptional responses under the action of the crude toxins. A total of 6,127 differentially expressed genes (DEGs) were identified. Among these genes, 3,150 were upregulated and 2,977 were downregulated. Gene Ontology (GO) and metabolic pathway enrichment analyses indicated that U. virens toxins mainly influenced glycometabolism, amino acid metabolism, and secondary metabolism of rice panicles. DEG analysis showed that the gene expression levels of 10 transcription factor families were significantly changed. Genes involved in phenylpropanoid biosynthesis, flavonoid biosynthesis, sugar transporters, and starch synthesis-related were significantly downregulated, including cytochrome P450, beta-glucosidase, CHS1, sucrose transporters, SWEETs, starch-branching enzymes, and UDP-glucose pyrophosphorylase. However, genes involved in programmed cell death (PCD) were significantly upregulated and contained cytochrome c, metacaspase, and protein kinase genes. The results indicate that U. virens toxins may act as the pathogenic factors to reduce stress resistance, disrupt total sugar accumulation and starch formation, and induce PCD.

SUN-Family Protein UvSUN1 Regulates the Development and Virulence of Ustilaginoidea virens

Ustilaginoidea virens, the causal agent of rice false smut disease, is an important plant pathogen that causes severe quantitative and qualitative losses in rice worldwide. UvSUN1 is the only member of Group-I SUN family proteins in U. virens. In this work, the role of UvSUN1 in different aspects of the U. virens biology was studied by phenotypic analysis of Uvsun1 knockout strains. We identified that UvSUN1 was expressed during both conidial germination and the infection of rice. Disruption of the Uvsun1 gene affected the hyphal growth, conidiation, morphology of hyphae and conidia, adhesion and virulence. We also found that UvSUN1 is involved in the production of toxic compounds, which are able to inhibit elongation of the germinated seeds. Moreover, RNA-seq data showed that knockout of Uvsun1 resulted in misregulation of a subset of genes involved in signal recognition and transduction system, glycometabolism, cell wall integrity, and secondary metabolism. Collectively, this study reveals that Uvsun1 is required for growth, cell wall integrity and pathogenicity of U. virens, thereby providing new insights into the function of SUN family proteins in the growth and pathogenesis of this pathogen.

Detection of Ustiloxin A in urine by ultra-high-performance liquid chromatography-tandem mass spectrometry coupled with two-step solid-phase extraction

Due to global outbreak of rice false smut disease, ustiloxin A (UA) was detected in rice. However, accurate methods for monitoring UA in human body fluids were lacking. In this context, a UPLC-MS/MS method based on two-step SPE was constructed for measuring UA in urine. The limits of UA quantification in human and mice urine were 58.3 and 108.7 ng/L, respectively. The proposed method was applied to detect UA in urine samples collected from human and mice. After dietary exposure, the contents of UA in mice urine were from 6.03 to 16.76 μg/g of creatine, accounting for approximate 14% of daily intake dose. Furthermore, due to the trace residues in rice (78–109 ng/kg), no detectable UA was observed in the urine of 20 volunteers. To the best of our knowledge, it is the first time to report the occurrence of UA in mammal urine.

Higher relative humidity and more moderate temperatures increase the severity of rice false smut disease in the rice–crayfish coculture system

AbstractRice false smut, a devastating grain disease in rice, is a great challenge to global food security. Rice–crayfish coculture (RC) has been widely used in recent years because it increases farmers' income, stabilizes rice yield, and reduces the use of pesticides and chemical fertilizers. Currently, rice false smut is becoming a threat to the stability of RC systems. A field experiment demonstrated that rice false smut in RC was much more serious than the disease in rice monoculture (RM) among most rice varieties in both 2019 and 2020. The fold change (RC vs. RM) range of the disease index of different rice varieties ranged from 1.23 to 19.35. Some varieties displayed resistance to rice false smut in RM, but were susceptible in RC, suggesting that the RC system that utilizes deep water irrigation is a better model than the RM to evaluate the resistance of rice varieties to false smut. Under the RC system, varieties YG 16, GBYJZ, and HD 5 displayed good natural resistance to rice false smut. A three‐way ANOVA with year, rice varieties, and culture types as factors showed that each factor had highly significant effects on the disease index. To identify the main factors causing differences between the RC and RM systems, we recorded the field microclimate around rice panicles. In comparison with RM, RC showed higher relative humidity (RH) and more moderate temperatures from the rice booting stage to early filling stage. Under simulated conditions of RC and RM, the germination rate of U. virens conidia under RC was significantly higher than that under RM. These findings indicate that higher RH and more moderate temperatures increase the severity of rice false smut disease in the RC system, and this provides unique insights into how to manage the threat of rice false smut.

The Flower-Infecting Fungus Ustilaginoidea virens Subverts Plant Immunity by Secreting a Chitin-Binding Protein.

Ustilaginoidea virens is a biotrophic fungal pathogen specifically colonizing rice floral organ and causes false smut disease of rice. This disease has emerged as a serious problem that hinders the application of high-yield rice cultivars, by reducing grain yield and quality as well as introducing mycotoxins. However, the pathogenic mechanisms of U. virens are still enigmatic. Here we demonstrate that U. virens employs a secreted protein UvCBP1 to manipulate plant immunity. In planta expression of UvCBP1 led to compromised chitin-induced defense responses in Arabidopsis and rice, including burst of reactive oxygen species (ROS), callose deposition, and expression of defense-related genes. In vitro-purified UvCBP1 protein competes with rice chitin receptor OsCEBiP to bind to free chitin, thus impairing chitin-triggered rice immunity. Moreover, UvCBP1 could significantly promote infection of U. virens in rice flowers. Our results uncover a mechanism of a floral fungus suppressing plant immunity and pinpoint a universal role of chitin-battlefield during plant–fungi interactions.

Consequences of Ustilaginoidea virens infection, causal agent of false smut disease of rice, on production and grain quality of rice

Nowadays, false smut of rice, caused by Ustilaginoidea virens, is a disease of interest in the world. Presently, its traditional status as ‘minor disease’ has changed with widespread reports of severity from all the rice growing countries of the world. While many reports are available on the yield loss from the disease, little is known of its effect on grain quality. The present study is planned mainly to evaluate the effect of false smut disease on grain quality of different rice varieties from India. False smut had significant effect on yield (loss of 0.7–8.6%), cooking and nutritional qualities of many popular Indian varieties. Significant changes (p < 0.05) in qualitative characters like hulling, milling, head rice recovery, kernel length after cooking, alkali spreading value, water uptake capacity and gel consistency were observed. Nutritional qualities like total protein content were variable within the ‘healthy’ varieties as well as within the ‘diseased’ varieties but the reduction of protein content in diseased grains over healthy was not significant. Amylose content and total phenol were found to be significantly high (p < 0.01) whereas antioxidant activities were significantly low (p < 0.01) in ‘diseased’ grains. All these changes in different quality parameters are emphasizing the impact of the disease on nutritional properties. This report is first of its kind from India and provides a template for further in-depth study to combat the disease so as to restrict yield loss and maintenance of rice grain quality.

Effect of calcined lime (CaO) on chlamydospores of the rice false smut pathogen, Villosiclava virens, and their root attachment and infection

AbstractRice false smut caused by Villosiclava virens is a devastating disease. The smut balls contain chlamydospores, which fall onto paddy soils to become the primary inoculum. After transplanting, the chlamydospores subsequently germinate and infect rice roots. The application of a CaO‐containing fertilizer to paddy soils can inhibit the development of rice false smut disease; however, the underlying mechanism is unknown. In this study, we evaluated the suppression of chlamydospore behaviour due to CaO. Specifically, we clarified the effects of the following on chlamydospore morphology and germination: (a) pH, (b) calcium (Ca) concentration, (c) Ca concentration (pH adjusted to 6.5), and (d) CaO‐added soil solution. Germination was suppressed at pH 4 and 10, in contrast with the normal germination at pH 6, 7, and 8. Treatments with more than 10 mg/L Ca melted the outer layer of chlamydospores and suppressed germination regardless of whether the pH was adjusted to 6.5. A saturated CaO solution induced bursting of chlamydospores. Suppressed germination and a melted outer chlamydospore layer were also observed, even though the soil buffering effect initially prevented the CaO‐mediated pH increase. Furthermore, the chlamydospores within 15 mm from the CaO small lump exhibited suppressed germination in soil. In addition, there was no effect of CaO treatment on chlamydospore attachment to rice roots and hyphal invasion of rice roots in in vitro inoculation tests. These results suggest that Ca concentration is an important factor for inhibiting the occurrence of rice false smut disease.

Proteomic Analysis of Mycelial Exudates of Ustilaginoidea virens.

Rice false smut (RFS) disease, which is caused by Ustilaginoidea virens, has been widespread all over the world in recent years, causing irreversible losses. Under artificial culture conditions, exudates will appear on colonies of U. virens during the growth of the hyphae. Exudation of droplets is a common feature in many fungi, but the functions of exudates are undetermined. As the executors of life functions, proteins can intuitively reflect the functions of exudates. Shotgun proteomics were used in this study. A total of 650 proteins were identified in the exudate of U. virens, and the raw data were made available via ProteomeXchange with the identifier PXD019861. There were 57 subcategories and 167 pathways annotated with Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, respectively. Through protein–protein interaction (PPI) network analysis, it was found that 20 proteins participated in the biosynthesis of secondary metabolites. Two separate PPI analyses were performed for carbon metabolism and microbial metabolism in diverse environments. After comparing and annotating the functions of proteins of the exudate, it was speculated that the exudate was involved in the construction and remodeling of the fungal cell wall. Pathogenicity, sporulation, and antioxidant effects might all be affected by the exudate.

Fungicidal Management of False Smut Disease in Rice Caused by Ustilaginoidea virens

False smut of rice caused by the fungus Ustilaginoidea virens has been recorded, in recent years, in the all rice growing areas of State Uttar Pradesh, India. Recommended fungicides are not yet available for chemically controlling the disease. Therefore, uses of unregistered fungicides are common by the farmers, for the management of the disease. The present study, was undertaken to identify effectiveness of fungicides to control false smut of rice. Four systemic fungicides (Propiconazole 25% EC @ 1.0 ml/L, Azoxystrobin 18.2% + Difenconazole 11.4% SC @ 0.5 g + 0.5 ml/L, Azoxystrobin 18.2% @ 1.0 g/L and Tebuconazole 250 EC @ 1.0 ml/L) were evaluated as foliar application in the naturally induced diseased rice, at five different locations in district Siddharthnagar, Uttar Pradesh. Fungicide was applied twice, first at panicle initiation and second at early flowering stage. All the fungicides applied were found effective in controlling the disease. As compared to the untreated (only water application), the fungicide ‘Propiconazole 25% EC’ reduced the maximum disease severity by 93.57%, followed by ‘Azoxystrobin 18.2% + Difenconazole 11.4% SC @ 0.5 g + 0.5 ml/L’, Fungicide Tebuconazole 250 EC @ 1.0 ml/L was found least effective in controlling the disease. It is concluded that more multi-location experiments will be required to reach a decisive conclusion on foliar chemical options for controlling rice false smut disease in eastern parts of Uttar Pradesh.