Narrow Brown Leaf Spot Research Articles

Comparative analysis of paddy leaf diseases sensing with a hybrid convolutional neural network model

The major food in south India is Paddy. Early detection of leaf disease can increase the production of crops. In the agricultural field, farmers can control the spreading of leaf disease with the help of the modeling of automated disease classification. In comparison to the manual approach to paddy leaf infection detection via visual examination, automated identification of rice illnesses using an image of the paddy leaf may be advantageous. Deep learning, a highly well-liked and effective machine learning method, has recently demonstrated considerable promise in the categorization task of images. In this work, Contrast Limited Adaptive Histogram Equalization (CLAHE) pre-processes the augmented images of paddy leaves. The Gray level co-occurrence metrics (GLCM) model then extracts the features from an image of the pre-processed paddy leaves. The five disease classes of paddy leaves were finally identified using the hybrid CNN model as follows: Bacterial Leaf Blight (BLB), Sheath Rot (SR), Narrow Brown Leaf Spot (NBLS), Brown Spot (BS) and Leaf Smut (LS). MATLAB platforms handle implementation works. While compared to the previous approaches, the proposed model reveals the superiority of paddy leaves classification.

Identification of Pests, Diseases, and Nutrient Deficiencies in Rice (Oriza Sativa L.) Variety Sunggal

This study aims to identify pests, diseases and nutrient deficiencies in the Sunggal variety of rice (Oriza sativa L.). This research was conducted in June 2023. The research location was carried out in rice fields belonging to farmers in Sidorejo Hamlet, Polokarto District, Sukoharjo Regency. This research is descriptive qualitative by making direct observations or observations on rice fields, interviews and literature. The results showed that there were 7 pests that attacked this single variety rice plant, consisting of 5 pests from the insect class (insects), 1 from the mollusk class, and 1 from the aves class. Pests caused by insects (insects), namely: rice bug (Leptocorisa oryzae), ground bed bug (Scotinophara coarctata), white rice stem borer (Scirpophaga innotata Walker), armyworm (Spodoptera litura), grasshopper (Oxya servile). Caused by molluscs, namely the golden snail (Pomacea canaliculate) and caused by birds, namely sparrows (Lonchura sp). While there are 6 caused by diseases, namely caused by fungi/fungi there are 5 and caused by bacteria there is 1. Among those caused by fungi/fungus namely: brown leaf spot on rice (Helminthosporium oryzae), narrow brown leaf spot on rice (Cercospora oryzae), stem rot in rice (Sclerottium oryzae), rice leaf blight (Rhizotonia solani) and leaf blast (Pyricularia grisea). Caused by bacteria, namely bacterial leaf blight of rice (bacteria: Xanthomonas oryzae pv oryzae). Then lastly there is one that is caused by a lack of nutrients, namely: potassium deficiency.

A High-Quality Genome Assembly for Cercospora janseana, Causal Agent of Narrow Brown Leaf Spot of Rice.

Cercospora janseana causes narrow brown leaf spot of rice. A nearly complete telomere-to-telomere reference genome was assembled with a combination of Oxford Nanopore and Illumina sequences. The genome assembly has a total length of 39,075,509 bp and consists of 15 chromosomes, 14 of which have telomeric repeats at both ends. The assembly N50 is 2.97 Mb and the L50 is five contigs. RNA-seq-mediated gene annotation identified 10,850 genes, including 955 predicted secreted proteins and 361 predicted effector proteins. This highly contiguous and almost complete C. janseana reference genome will be a vital resource for further investigation of host-pathogen interactions and genome evolution within this pathosystem. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

English

Narrow brown leaf spot disease of rice caused by fungus Cercospora oryzae Miyake emerged as potential threat to rice crop in previous few years worldwide and can cause more than 40% yield loss. The disease symptoms were noted on various commercially important rice varieties in the rice growing districts of Punjab province of Pakistan. Hence, the studies were planned to assess the effects of Propiconazole fungicide application timings and different rice varieties on the severity of narrow brown leaf spot (NBLS) disease of rice to develop an accurate management strategy for the disease. The Propiconazole fungicide was tested at three various growth phases (early booting, late booting, and soft dough) of four rice varieties against the percent severity of the NBLS disease The experiments were designed under strip-plot (crisscross) design with four replications at research area of Plant Pathology Department, University of Agriculture Faisalabad. Analysis of variance has demonstrated that the main and interactive effects of fungicide applications and rice varieties were found significant. The main effects of years were found non-significant but their interactions with fungicide application timings and rice varieties were significant. Fungicide applications at soft dough and late booting phases of rice variety B-515 were found least effective to reduce the disease severity, respectively. Fungicide application at early booting of rice variety PK-1121 was found most effective by reducing the maximum percent diseases severity (47.25%) compared to control. It is concluded that, to minimize hazardous effects of chemicals on the environment by practicing multiple sprays at inappropriate growth phases of rice crop, fungicides must be applied during the early and late booting phases of rice varieties on mildly resistance, susceptible and highly susceptible rice varieties to reduce NBLS disease severity and to enhance the rice production and quality

Assessing narrow brown leaf spot severity and fungicide efficacy in rice using low altitude UAV imaging

The utilization of unmanned aerial vehicle (UAV)-based imaging systems offers precise detection of plant diseases and aids in decision-making regarding fungicide applications to optimize disease control. This study employed a twin-lens multispectral camera mounted on a low-altitude UAV to capture imagery data from rice field plots that were treated with different fungicides. The objectives of this study were to assess the severity of narrow brown leaf spot (NBLS) caused by Cercospora janseana and to evaluate the efficacy of fungicide control. Eighteen color features and vegetation indices were extracted from RGB images, while nine color features and vegetation indices were extracted from multispectral images. Through correlation analysis, four spectral features, namely Lab-a, ExGR, VDVI, and g, were found to exhibit high correlations with disease severity. Specifically, RGB imagery had greater correlation coefficients (exceeding 0.95) for both ExGR and Lab-a features compared to multispectral imagery. A multifeature inversion modeling approach was employed, using support vector regression with the top four spectral features to predict NBLS severity. The results indicated R2 values were above 0.93 for all support vector regressions. Furthermore, the efficacies of ten different fungicide treatments were evaluated, with UAV imaging consistently aligning with ground truth rating data in terms of efficacy ranking. These results demonstrate the potential of UAV imagery for use as a valuable tool for NBLS detection and assessing fungicide efficacy, offering significant benefits in the management of NBLS, which is a globally important disease in rice.

Effect of Nutrient Management and Weeds on Incidence of Fungal Diseases in Rice

High-input, modern agriculture uses large amounts of energy, water, fertilizers, and pesticides to produce high crop yields. One of the major bottlenecks of the modern agriculture in the tropics is substantial yield losses due to fungal diseases including rice blast, leaf spots and leaf scald. The aim of this study was to compare the incidence of fungal diseases in judicious nutrient management systems, including organic, integrated, and conventional, under different weed categories during dry season (May to September 2020) and wet season (November 2020 to March 2021). Rice disease incidence were collected for both seasons from 48-84 days after sowing. Additionally, disease incidences on grasses and sedges weeds were also calculated. Brown spot, narrow brown leaf spot, leaf scald, and rice blast incidences were substantial in wet season, while the disease incidences during dry season in 2020 were negligible. The disease incidences were significantly higher (P<0.05) in organic and conventional input systems compared to the integrated input system. Disease incidences of brown spot and leaf scald were found in the dry season. Higher disease incidences were recorded in the wet season than in the dry season. The incidences of the brown spot were higher on sedges than in grasses and vice versa were observed for narrow brown leaf spot disease. Leaf scald incidences were positively correlated with the significant nitrogen status of the rice crop. Disease incidence was low in integrated input system compared to conventional and organic input systems, while weeds were reported as alternative hosts. It can be concluded that the integrated nutrient management with recommended dosage of nitrogen application with proper weed management can lead to low disease incidents, hence is ecologically more sustainable.

Effect of Sowing Times and Rice Varietal Resistance on the Severity of Narrow Brown Leaf Spot Disease in Relation to Environmental Conditions

The objective of this study was to investigate the effects of sowing times and genetic resistance of 10 commercially important rice varieties on the percent disease severity (PDS) of narrow brown leaf spot (NBLS) caused by Cercospora oryzae. Two sowing time treatments (mid-May and mid-June) each year were evaluated for this 2-year study. Rice varieties were drill seeded and arranged in randomized complete block designed plots with four replications for each variety. The effects of environmental factors (high and low temperature, relative humidity and precipitation) on the NBLS severity of the rice varieties at both sowing times were also evaluated. Disease data was analyzed using computer software GenStat 10th edition. Results: By changing cultivation timing of rice varieties, B-Chenab, KSK-434, PK-386, B-Kissan, and KSK-133 from mid-May to mid-June, their resistance levels were also changed from a higher to a lower. Weather conditions during the mid-June cultivation of 2019 induced a higher level of disease severity than did the mid-May weather conditions of 2018. The variation in temperatures affected the percent disease severity more as compared to relative humidity and precipitation. High temperature of 31-33˚C and low temperature of 18-21˚C were found to be most effective in enhancing the NBLS development. Minimum NBLS severity 4.75% and 8.25% was noted on variety B-515 in mid-May and mid-June sowings respectively. Thus, its rating changed from resistant to mildly susceptible by changing sowing timing. Rice variety PK-1121 depicted maximum NBLS severity 60.25 % in mid-May sowings, rated as very highly susceptible, while severity increased to 79.25% in mid-June sowings, and rated as completely susceptible. It is concluded that the severity of NBLS was affected by genetic resistance level of rice varieties, sowing times and weather conditions thus consideration of these factors is the key to the integrated management of the NBLS in rice.

Factors affecting incidence of narrow brown leaf spot of rice caused by <i>Passalora janseana</i>

The Ceylon Journal of Science is published by the University of Peradeniya, Sri Lanka. Full text available. The journal also has its own website. The Ceylon Journal of Science is a continuation of the Ceylon Journal of Science (Biological Sciences) which is no longer being published as a separate journal. The history of the journal can be found here.From May 2020, Ceylon Journal of Science is indexed in DOAJ.

Effect of Nitrogen fertilizer, weed control and seed rate on incidence and severity of narrow brown leaf spot in rice cultivation under the dry zone of Sri Lanka

Effect of Nitrogen fertilizer, weed control and seed rate on incidence and severity of narrow brown leaf spot in rice cultivation under the dry zone of Sri Lanka

Hybrid Rice Outperforms Inbred Rice in Resistance to Sheath Blight and Narrow Brown Leaf Spot.

Sheath blight (ShB; caused by Rhizoctonia solani AG1-1A) and narrow brown leaf spot (NBLS; Cercospora janseana) are among the most important diseases affecting rice production in Texas and other southern parts of the United States. Because of the high yield potential, hybrid rice acreage is continually increasing. Understanding the relative levels of resistance to ShB and NBLS in hybrids compared to those of inbreds is important for effective disease management; however, this information remains largely unknown. A comparison of the performance of hybrid rice and inbred rice was performed involving 173 hybrid and 155 inbred genotypes (cultivars and elite breeding lines) over the course of five crop seasons (2016 to 2020) and two locations in Texas. The results showed that genotype, cultivar type (hybrid or inbred), location, and their interactions had significant effects on the severity of ShB and NBLS. The ShB severity in hybrid genotypes was significantly lower than that in inbred genotypes, with an average reduction of 27% in disease severity during the 5-year, two-location evaluation. Most (53%) of the hybrid genotypes were rated moderately resistant, whereas almost all (97%) of the inbred genotypes ranged from very susceptible to moderately susceptible. Similarly, NBLS severity in hybrid genotypes is significantly lower than that in inbred genotypes. All but four hybrid genotypes exhibit immune reactions to NBLS. In contrast, 77% of inbred genotypes exhibit NBLS symptoms, with disease resistance reactions ranging from susceptible to resistant. The results demonstrate that hybrid rice is generally less susceptible to sheath blight and has a higher level of resistance against NBLS compared with inbred rice.

Identification and mapping of a novel resistance gene to the rice pathogen, Cercospora janseana

The genetic architecture of resistance to Cercospora janseana was examined, and a single resistance locus was identified. A SNP marker was identified and validated for utilization in U.S. breeding germplasm Cercospora janseana (Racib.) is a fungal pathogen that causes narrow brown leaf spot (NBLS) in rice. Although NBLS is a major disease in the southern United States and variation in resistance among U.S. rice germplasm exists, little is known about the genetic architecture underlying the trait. In this study, a recombinant inbred line population was evaluated for NBLS resistance under natural disease infestation in the field across three years. A single, large-effect QTL, CRSP-2.1, was identified that explained 81.4% of the phenotypic variation. The QTL was defined to a 532 kb physical interval and 13 single nucleotide polymorphisms (SNPs) were identified across the region to characterize the haplotype diversity present in U.S. rice germplasm. A panel of 387 U.S. rice germplasm was genotyped with the 13 haplotype SNPs and phenotyped over two years for NBLS resistance. Fourteen haplotypes were identified, with six haplotypes accounting for 94% of the panel. The susceptible haplotype from the RIL population was the only susceptible haplotype observed in the U.S. germplasm. A single SNP was identified that distinguished the susceptible haplotype from all resistant haplotypes, explaining 52.7% of the phenotypic variation for NBLS resistance. Pedigree analysis and haplotype characterization of historical germplasm demonstrated that the susceptible haplotype was introduced into Southern U.S. germplasm through the California line L-202 into the Louisiana variety Cypress. Cypress was extensively used as a parent over the last 25 years, resulting in the susceptible CRSP-2.1 allele increasing in frequency from zero to 44% in the modern U.S. germplasm panel.

Distribution of narrow brown leaf spot disease of rice (Cercospora oryzae Miyake) in North Sumatra

Narrow brown leaf spot (NBLS) disease is an important disease in rice plants in Indonesia and other rice-producing countries in Asia. This disease has been reported as one of the main diseases of rice in rice-producing countries, including in Indonesia. This research was aimed to determine the distribution of narrow brown leaf spot deseasew which is caused by fungal pathogen Cercospora oryzae Miyake in North Sumatra. This research was conducted by survey method which calculated the disease incidence and disease severity of disease in rice plants in seven regions in the province of North Sumatra. The results showed that the disease intensity. The highest disease incidence and disease severity of NBLS disease was found in Siabal Abal Village, Sipahutar District of North Tapanuli with 100% of disease incidence and 95% of disease severity.

Field Performance of BAU-Biofungicaide for Management of Narrow Brown Leaf Spot and Bacterial Leaf Blight Disease of Rice CV. BRRI Dhan29

Potent (0.1%) and BAU-Biofungicide (2%) revealed the significant reduction both in disease severity and incidence of narrow brown leaf spot disease, and the lowest disease severity and incidence of bacterial leaf blight disease were 3.00% and 5.83%, respectively in BRRI dhan29 in 2012 year. BAU-Biofungicide (Trichoderma based preparation), extract of garlic (Allium sativum) and neem (Azadirachta indica), Bavistin DF (Carbandazim) and Potent 250 EC (Propiconazole) were evaluated in controlling narrow brown leaf spot and bacterial leaf blight disease (Xanthomonas oryzae pv. Oryzae) under field condition for producing seed quality and controlling seed borne pathogen of rice cv BRRI dhan29 during 2012 and 2013 years. Maximum normal seedling (87.67%) and 37.49% higher increase in vigour index on seed quality test of harvested seeds were observed with BAU-Biofungicide (3%) over control. BAU-Biofungicide (2 and 3%) and Potent 250 EC (0.1%) were found to be effective in controlling seed borne pathogens. BAU-Biofungicide has also been attributed as profound contribution on quality seed production of harvested seed of BAU-Biofungicide sprayed plot.

Ketahanan Beberapa Varietas Padi terhadap Cercospora oryzae

<p>Rice is the source of staple food for most Indonesian people. The demand is continually increasing as the impact of increasing the people population. Sustainable development of rice must be done by the government. One of the problems in rice production is narrow brown leaf spot disease caused by <em>Cercospora oryzae</em>. This study aimed to determine the resistance of some varieties of rice to <em>C. oryzae</em>. The study was conducted on a field scale with natural inoculation and greenhouse with artificial inoculation using <em>C. oryzae</em> conidia suspension density of 10<sup>5</sup> conidia ml<sup>-1</sup>. The parameters observed, were incidence of disease, disease severity, the rate of infection, Area Under the Disease Progress Curve (AUDPC), and crops production. The result showed in the field that rice varieties of Gagak Hitam and Pandan Wangi were categorized as moderat resistant, while IR64, Inpari4, Sunggal and Ciherang showed high susceptible to <em>C. oryzae</em>. The results of greenhouse study showed that Hitam Gagak and Pandan Wangi rice varieties were categorized as resistant and IR64, Inpari4, Sunggal, Ciherang were moderate resistant (RR) against <em>C. oryzae</em>. The resistance of rice varieties affected by the interaction between pathogen genes that determine virulence and host genes that determine the resistance of the host plant.</p>

Optimum timing of propiconazole to manage narrow brown leaf spot in the main and ratoon rice crops in Texas

Narrow brown leaf spot (NBLS) is a foliar disease of rice caused by Cercospora janseana. The present study was conducted to evaluate the effects of frequency and timing of propiconazole (PropiMax) applications on rice NBLS severity and grain yield in the main and ratoon (second) crops. Field experiments were established at Eagle Lake and Beaumont, Texas in the years 2010–2012 and 2014 to 2016 respectively. The Eagle Lake trials evaluated two rates of propiconazole (0.16 and 0.32 kg a.i. ha−1) at two application timings (boot and heading growth stages) on the main crop, in combination with or without a single application at the boot stage on the ratoon crop. The Beaumont trials evaluated four main crop application timings (7 days after panicle differentiation, boot, heading, and 7 days after heading) at 0.32 kg a.i. ha−1 in combination with a single application at boot stage on the ratoon crop. Fungicide application frequency of up to three main-crop applications with a single ratoon-crop application was also evaluated in the Beaumont trials. NBLS severity on the rice flag leaves was visually evaluated prior to harvest in the main and ratoon crops. At both locations, fungicide treatments significantly reduced NBLS severity in the main and ratoon crops compared to the non-sprayed control in each of year evaluated. Among the single fungicide application treatments, NBLS severity in the main crop was consistently lower when the fungicide was applied at the heading stage than at any other application stages. Fungicide application at any stage of the main crop significantly reduced NBLS severity in the ratoon crop. An additional fungicide application at the boot stage of the ratoon crop further reduced NBLS severity in four of the six seasons tested. In the Eagle Lake trials, both rates of the fungicide evaluated were comparable in their efficacy in reducing NBLS severity. In Beaumont trials, where multiple fungicide applications were evaluated, main-crop NBLS severity decreased as the number of applications increased. At these low to moderate NBLS severity levels, rice grain yields were not significantly affected, at either of the locations.

Registration of ‘CLJ01’ Rice

‘CLJ01’ (Reg. No. CV‐152, PI 687326), a Clearfield (BASF) long‐grain aromatic (Jazzman) rice (Oryza sativa L.) cultivar, was developed by the Louisiana State University Agricultural Center at the H. Rouse Caffey Rice Research Station near Crowley, LA, and approved for release by the director of the Louisiana Agricultural Experiment Station in 2018. CLJ01 is the first aromatic rice cultivar to be released for use with the Clearfield rice production systems. CLJ01 was derived from the cross ‘Jazzman’/08CLR004//RU0802146/3/RU1002146, made 2010 and advanced in 2014 as an F4 row selection. Preliminary testing in 2015 indicated high yield potential and favorable agronomic and grain characteristics. CLJ01 was evaluated across 27 trials in eight locations in 2016–2017. Three high‐yielding commercial Clearfield cultivars (‘CL111’, ‘CL151’, and ‘CL153’) and two commercial aromatic cultivars (‘Della‐2’ and ‘Jazzman‐2’) were included as checks. Grain yield of CLJ01 was 7.95 t ha−1 compared with 8.16 t ha−1 for CL111, 9.18 t ha−1 for CL151, 8.88 t ha−1 for CL153, 7.35 t ha−1 for Della‐2, and 6.15 t ha−1 for Jazzman‐2. The leaves, lemma, and palea are glabrous, the apiculus is has a purple color, and the grain is aromatic. CLJ01 is moderately susceptible to blast and susceptible to sheath blight, bacterial panicle blight, narrow brown leaf spot, and the physiological disorder straighthead.

Plant-Based Culture Media for Improved Growth and Sporulation of Cercospora janseana.

Cercospora janseana is the causal agent of narrow brown leaf spot, one of the major diseases of rice in the United States. In vitro studies were conducted to evaluate various plant-based agar media in comparison with potato dextrose agar (PDA) for their effects on radial growth and sporulation of C. janseana. The agar media were evaluated individually with the following plant-extract ingredients: fresh rice leaves, dried rice leaves, dried rice stems, dried rice roots, dried rice hulls, dried rice straw, rice bran, dried sorghum leaves, and dried barnyard grass leaves. Plant-based extracts obtained from 25, 50, 100, or 200 g/liter (plant material/water) were tested either alone or in combination with 10 and 20% clarified V8 juice. PDA served as the control medium. Media with 10 and 20% V8 juice were also included for comparison. Media were inoculated with a disc of 1-week-old actively growing C. janseana at the center of Petri plates and incubated at 28°C with a 12/12-h (light/dark) cycle for 2 weeks. Radial growth was measured at 7 and 14 days after inoculation (DAI), whereas sporulation was measured at 14 DAI. Radial growth and sporulation differed among various media and their amendment concentrations. Media with extracts of fresh rice leaves, dried rice leaves, dried rice stems, dried barnyard grass leaves, and clarified V8 juice enhanced radial growth compared with the PDA control. Of all the agar media evaluated, fresh rice leaf extract amendment at 25 g/liter with no V8 supplementation consistently supported the greatest radial growth, and 10% V8-only medium resulted in greater sporulation of C. janseana than other media evaluated.

Antagonism of rice phylloplane fungi against Cercospora oryzae

Narrow brown leaf spot (NBLS) caused by Cercospora oryzae Miyake is one of the important obstacle in rice cultivation that can decrease the productivity up to 40%. It has been known well that some phylloplane fungi are antagonistic to some leaf diseases. Phylloplane fungi of rice however haven’t been studied much and poorly understood as biological control agent of rice pathogen such C. oryzae. The research aimed to study the antagonism of some phylloplane fungi of rice against C. oryzae. At least 14 isolates of phylloplane fungi were collected which consisted of six pathogenic and eight nonpathogenic variants. All of nonpathogenic isolates were antagonistic against C. oryzae both in vitro and only one isolate could not inhibit the infection of the pathogen in vivo. Some isolates were identified as Aspergillus, Mucor, Penicillium, Fusarium, and Trichoderma. The isolate of Mucor and Fusarium could inhibit the highest growth of pathogen on potato dextrose medium that were at 36.0% and 35.5% respectively. Whereas on artificial inoculation on rice, some isolates such Penicillium and Fusarium could inhibit most effectively and were significantly different to Mencozeb application with dosage 5g L-1.

Efficacy of BAU-Biofungicide, Chemical Fungicides and Plant Extracts on Rice (Oryza Sativa L) Diseases and Yield

Efficacy of BAU-Biofungicide, Chemical Fungicides and Plant Extracts on Rice (Oryza Sativa L) Diseases and Yield Extract of garlic (Allium sativum L.), Neem (Azadirachta indica L.); BAU-Biofungicide (Trichoderma based preparation) and Bavistin DF (Carbandazim) and Potent 250 EC (Propiconazole) were tested in laboratory and field conditions for eco-friendly management of diseases of rice (Oryza sativa, L.) cv BRRI dhan28. BAUBiofungicide (2%) was found to have profound effect in inhibiting the mycelial growth of Bipolaris oryzae (brown spot), Cercospora oryzae (narrow brown leaf spot) and Rhizoctonia solani (sheath blight) in vitro and marked reduction of disease incidence of brown spot, narrow brown leaf spot and sheath blight in the field. It was noted that significantly low incidence of narrow brown leaf spot and sheath blight disease was observed in plots sprayed with Carbendazim (0.1%) in the field as well as mycelia growth inhibition of Cercospora oryzae and Rhizoctonia solani was found in Carbendazim (0.1%) under laboratory condition. Highest (20.20%) grain yield was increased in Propiconazole (0.1%), while (17.84%) higher increase grain was obtained with BAU-Biofungicide (3%). No statistical significant difference was observed between yield of BAU-Biofungicide and Propiconazole. Most of the detected seed borne pathogens were controlled by BAU-Biofungicide and Propiconazole. Maximum germination (%) was observed over control when seeds were treated with BAU-Biofungicide (2%). BAUBiofungicide (2%) exhibited (40.45%) higher increase in vigour index over control. Results indicated that the greatest antagonistic effect of BAU-Biofungicide was found in reducing disease incidence and increased grain yield as an alternative option of synthetic fungicide.

Use of UAV images to assess narrow brown leaf spot severity in rice

Abstract: Unmanned aerial vehicle (UAV) remote sensing is a potential tool to reduce crop yield losses caused by numerous diseases through near real-time detection and monitoring on disease progression. However, limited research has been conducted to effectively integrate this technology into current crop management systems for disease control. In this study, the feasibility of assessing the severity of narrow brown leaf spot (NBLS) in rice based on UAV remote sensing platform was explored. RGB and NIR images were obtained using Sentera Multispectral Double 4K sensor attached to DJI INSPIRE 2 drone flying at two altitudes (10 m and 15 m). Ground-truth data on disease severity were collected through visual assessment of field plots with different levels of disease severity. Five out of 21 vegetation indices have a coefficient of determination ( R 2 ) value greater than 0.8 based on unitary linear regression. The index with the highest R 2 is Excess Green minus Excess Red (ExGR). The results of unitary regression analysis demonstrated more suitability of using RGB images for rice NBLS assessment over NIR images. Further analyses were conducted on disease-infected plot data that were divided into two groups with 2/3 of the plot data as modeling set and the remaining as evaluation set. The ExGR has the highest R 2 value and the lowest RMSE value in both modeling and evaluation sets regardless of drone flight height (10 m or 15 m). The RMSE at 15 m is lower than at 10 m but there was no significant difference of R 2 , thus the 15-m flight height is better than the 10-m height in detecting the levels of disease severity. The comparison of ExGR and HIS-H demonstrated that vegetation index is more suitability for detecting rice NBLS disease with more spectral information. When disease severity data were divided into two score groups (0 to 5 and 6 to 9 for the low and high levels of disease, respectively) or three score groups (0 to 3, 4 to 6 and 7 to 9 for the low, moderate and high levels of disease, respectively), the ExGR was more suitable for the detection of the high levels of disease. These results demonstrated the feasibility of using UAV images as a potential tool to assess the severity of NBLS, an important fungal foliar disease in rice worldwide. Keywords: UAV remote sensing, multispectral sensor, narrow brown leaf spot, disease severity, rice DOI:  10.33440/j.ijpaa.20190202.47.  Citation: Cai N, Zhou X G, Yang Y B, Wang J, Zhang D Y, Hu R J.  Use of UAV images to assess narrow brown leaf spot severity in rice.  Int J Precis Agric Aviat, 2019; 2(2): 38–42.