Severity Of Bacterial Leaf Blight Research Articles

Isolation and identification of various isolates ofXanthomonas oryzae pv. oryzae (Xoo) (Ishiyama) from different parts of Tamil Nadu and Evaluate its virulence under pot trial

Rice, a staple crop and lifeline for millions, is India’s second most important crop after wheat, with the country being one of Asia’s leading producers. However, bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) poses a severe threat to rice production across both tropical and temperate regions due to its high epidemic potential. This study focused on isolating and evaluating the virulence of various Xoo isolates from different rice-growing areas in Tamil Nadu under controlled pot trials. Among the isolates, Xoo3 was identified as the most virulent, causing a BLB severity of 43.9%, while Xoo6 showed the lowest virulence with a 29.8% severity rate. These findings highlight the variability in pathogenicity among Xoo isolates and underscore the importance of targeted disease management practices to mitigate BLB impact on rice yields in affected regions.

Efektivitas Frekuensi dan Volume Penyemprotan Daun dengan Agens Hayati Filosfer dalam Meningkatkan Pertumbuhan Tanaman dan Hasil Padi

ABSTRACT<br /><br />Increased of plant productivity in field determined by the use of quality seed from improved variety. The purpose of this research was to study the effect of frequency and volume of phyllosphere biological agents by foliar spray on rice plant infected by Xanthomonas oryzae pv. oryzae (Xoo) in improving plant growth, production of rice seed, and controlling bacterial leaf blight (BLB). This research was conducted at Seed Health Laboratory, Department of Agronomy and Horticulture, Bogor Agricultural University, and Muara Experimental Field, Rice Research Institute, March through September 2014. The experiment was conducted using a randomized complete block design with two factors, and replicates as blocks. The first factor was five levels of frequency of spraying with biological agents: P0 = control, P1 = Xoo seed inoculated then invigorated with biomatriconditioning, P2 = Xoo inoculated seed, then biomatriconditioned, and the plants were sprayed with phyllosphere biological agents F112 once, P3 = as P2, and the plants were sprayed with F112 twice, and P4 = as P2, and the plants were sprayed with F112 three times. The second factor was three levels of spray volume: i.e., 300, 400, and 500 L ha-1. Result of this experiment revealed that biomatriconditioning with rhizobacteria P. diminuta A6 and B. subtilis 5/B improved field emergence and seedling dry weight. Seeds applied with biomatriconditioning then followed by foliar spray with phyllosphere bacteria F112 at 40, 60, and 80 days after transplanting effectively reduced severity of BLB, increased plant dry weight and seed yield. All treatments increased yield as compared to untreated control. Volume of foliar application showed no significant difference, therefore, the lowest volume of 300 L ha-1 was recommended. <br /><br />Keywords: Bacillus subtilis 5/B, biomatriconditioning, Pseudomonas diminuta A6, Xanthomonas oryzae pv. oryzae

Perlakuan Agens Hayati untuk Mengendalikan Hawar Daun Bakteri dan Meningkatkan Produksi Benih Padi Sehat

ABSTRACT The research objectives were to evaluate biological agent treatments in controlling bacterial leaf blight (BLB) and increasing plant growth and seed production of rice. The experiment was conducted in the greenhouse and field using the same experimental design (randomized block design with two factors) and three replications. The first factor was seed treatments, i.e. negative control, positive control, streptomycin sulphate 0.2%, Pseudomonas diminuta + Bacillus subtilis, matriconditioning + streptomycin sulphate 0.2%, and matriconditioning + P. diminuta + B. subtilis. Spraying plants (second factor): untreated control, streptomycin sulphate 0.2%, biological agent F112, biological agent F198, and biological agent F57. In the greenhouse, matriconditioning + P. diminuta + B. subtilis improved seed germination, plant height, and plant dry weight. Spraying plants with biological agent F112 increased plant dry weight. Meanwhile, matriconditioning + P. diminuta + B. subtilis followed by spraying plants with biological agent F112 reduced the BLB severity. In the field, matriconditioning + P. diminuta + B. subtilis improved seedling dry weight. Matriconditioning + P. diminuta + B. subtilis and spraying plants with biological agents F112 controlled BLB and increased plant growth. However, all treatments were not able to increase healthy seed production. Keywords: matriconditioning, seed treatment, phyllosphere biological agents, Xanthomonas oryzae pv. oryzae

Effect of fungal and bacterial bioagent application on total phenolic content in rice leaves pre-inoculated with Xanthomonas oryzae pv. oryzae (Uyeda and Ishiyama) Dowson

Present study was carried out to observe the effect of fungal and bacterial bioagents on total phenolic content in rice leaves pre-inoculated with Xanthomonas oryzae pv. oryzae and on disease severity of bacterial leaf blight of rice. Two commercial formulations of Trichoderma harzianum (PBA-1) and Pseudomonas fluorescens (PBA-2) and four formulations of fluorescent pseudomonads and Trichoderma spp. viz, P. fluorescens (Pf 83, rice leaf isolate), fluorescent pseudomonad (FLP 88, rice leaf isolate), T. harzianum (rice leaf isolate), Trichoderma spp. (isolate 40, isolated from rice field soil) were evaluated. Significantly higher mean value of total phenolic content of rice leaves was observed with the application of bioagent formulations as compared to check (pre-inoculated with X. oryzae pv. oryzae), chemical treatment and healthy plant. Maximum mean total phenolic content (342.22 ?l/g) in rice leaves was observed with Pf 83, which was followed by PBA-2 (334.44 ?l/g) and T. harzianum (330.00 ?l/g). Decrease in disease severity of bacterial leaf blight was observed with the increase of total phenolic content in rice leaves which resulted in increased grain yield and 1000 grain weight.

Effect of bioagent application time against bacterial leaf blight of rice caused by Xanthomonas oryzae pv. oryzae (Uyeda and Ishiyama) Dowson

Present investigation was carried out to test the effect of time of application on efficacy of Trichoderma harzianum and Pseudomonas fluorescens formulations against bacterial leaf blight of rice, under field condition. Foliar sprays with bioagent(s) in three time sequences i.e. 7 days before, simultaneously and 7 days after inoculation of Xanthomonas oryzae pv. oryzae inoculation significantly reduced disease severity over check during Kharif 2006 and 2007. Maximum reduction in bacterial leaf blight disease was obtained with the application of T. harzianum on 7 days before inoculation of pathogen during Kharif 2006 and 2007 and maximum increase in grain yield was obtained with the application of PBA-2 seven days before inoculation of pathogen. It was revealed that prophylactic spray of bioagents one week prior to pathogen inoculation was significantly (106 cfu/g) effective in reducing disease severity of bacterial leaf blight of rice as compared to chemical treatment.

Management of bacterial leaf blight of mango through antibiotics and bio-fungicide

An experiment was conducted in the net house, Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh, Bangladesh during 15 July 2012 to June 2013 to find out the efficacy of antibiotics and biofungicide for controlling bacterial leaf blight of mango. Six treatments were applied viz., (i) T1–Gentamycin @ 0.05%, (ii) T2– Erithromycin @ 0.05%, (iii) T3–Doxycycline @ 0.05%, (iv) T4–Copper sulphate @ 0.05%, (v) T5–BAU-biofungicide @ 2% and (vi) T6–Control. The treatment BAU-biofungicide was found good in controlling bacterial leaf blight of mango. This treatment increased 23.71% plant height, 53.33% branch over control and reduced 39.31% disease incidence and 48.50% disease severity when applied as foliar spray @ 2%. The second best control measure was found by gentamycin as it reduced 28.46% disease incidence and 46.43% disease severity when applied as foliar spray @ 0.05%, although other treatments reduced incidence and severity of bacterial leaf blight which were applied as foliar spray @ 0.05%.

Effect of antibiotics and BAU-biofungicide in controlling bacterial leaf blight of litchi

The experiment was carried out in the net house, Department of Plant Pathology, Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh during 16 July 2012 to June 2013 to find out the suitable management practices for controlling bacterial leaf blight of litchi by applying six treatments viz., (i) T1–Gentamycin @ 0.05%, (ii) T2– Erithromycin @ 0.05%, (iii) T3–Doxycycline @ 0.05%, (iv) T4–Copper sulphate @ 0.05%, (v) T5–BAU-biofungicide @ 2% and (vi) T6–Control. Per cent incidence and per cent severity have been found to decrease by applying BAU-biofungicide, copper sulphate and gentamycin, although other treatments showed good result in decreasing severity of bacterial leaf blight. BAU-biofungicide was found superior among the treatments as it increased 18.83% plant height, 43.50% branch over control and reduced 17.16% disease incidence and 63.03% disease severity over control when applied as foliar spray @ 2%. Copper sulphate reduced 13.85% disease incidence and 50.21% disease severity over control and graded second best control measure for bacterial leaf blight of litchi when applied as foliar spray @ 0.05%.

Capability of <i>Streptomyces</i> spp. in Controlling Bacterial Leaf Blight Disease in Rice Plants

Problem statement: Bacterial Leaf Blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo ) is the most damaging disease in lowland rice grow ing areas in Indonesia. Streptomyces spp. have been known as a producer of antimicrobia l compounds that can be used as biocontrol agents. This study examined the ability of three p romising indigenous Streptomyces isolates which were previously selected from in vitro agar media and greenhouse test to suppress natural infection of Xoo during dry and wet season trials in 2009/2010 a t the Muara Experimental Research Station, Bogor West Java, Indonesia. Approach: Streptomyces isolates (PS4-16, LBR-02 and LSW-05) were applied through seed coating in a peat-based carrie r followed by seedling soaking, spray treatment, or combination of both methods, either singly or in c ombination of two or three isolates. The number of Streptomyces population in the peat carrier at the time of inoc ulation was above 10 7 cell g -1 . The efficacy of Streptomyces was compared to that chemical spray using NORDOX 56 WP (a.i., zinc oxide 56%) and non-treatment. Treated and untreated seeds were grown in plots (5 ×5 m 2 ) and set in a randomized complete block design with four replications. Results: In the dry season experiment, application of Streptomyces spp. reduced BLB severity when compared to that of untreated plots, although did not reduce BLB incidence. PS4-16, applied singly through seed coating followed by seedlin g soaking, reduced the Area Under Disease Progress Curve (AUDPC) at 70 Days After Planting (DAP) to 1458, which was equally effective to the chemical s pray (AUDPC value 1434) and simultaneously promoted plant height and gave the highest rice yie ld. In the wet season trial PS4-16 and LBR-02, appl ied singly or in dual combination through seed coating followed by seedling soaking, suppressed BLB severity, PS4-16 was confirmed as the most effective isolate by reducing the AUDPC to 1923, which was not significantly different to the AUDPC value obtained from chemical spray treatment (1934). Conclusion/Recommendations: All Streptomyces isolates had a tendency to increase plant and yie ld compared to the chemically-sprayed and non-treated plots. For successful biological control of rice BL B, further development of a better formulation for lon g-term storage with an effective population density of Streptomyces and an assessment of its field efficacy in multi-l ocation trials are needed.

Assessment of the severity of bacterial leaf blight in rice using canopy hyperspectral reflectance

Bacterial leaf blight (BLB) is an important vascular disease of irrigated rice and serious infestations may cause a significant loss of yield. This study analyzed hyperspectral canopy reflectance spectra of two rice cultivars with different susceptibilities to BLB to establish spectral models for assessing disease severity for future site-specific management. The results indicated that wavebands from 757 to 1039 nm were the most sensitive region of the spectrum for the moderately susceptible cultivar TNG 67, whereas most narrow bands showed a significant relationship for the highly susceptible cultivar TCS 10. All the spectral indices (SIs) calculated had significant relationships with proportions of infested area in cultivar TCS 10, but only two SIs correlated significantly with cultivar TNG 67. The relation between the severity of the disease and spectral reflectance for the less susceptible cultivar TNG 67 can be improved by using a multiple linear regression approach.

Assessments of farm yield and district production loss from bacterial leaf blight epidemics in rice

The damage from natural epidemics of bacterial leaf blight (BLB) of rice caused by Xanthomonas oryzae pv. oryzae was examined in 400 farmers’ fields in four rice-growing districts of India during the wet seasons between 1995 and 1998. One hundred contiguous farm fields were rated for BLB on a 0–9 scale. Disease prevalence at levels above the economic threshold (score >5) ranged from 7 to 39%. Studies were made with samples from representational farms taken at the rate of one farm for every 10% disease prevalence out of 100 farms per district. The spatial pattern of BLB development within and among rice hills was either random or uniform. On the representational farms, the mean BLB severity was 65–71%. Disease injury caused highly significant reductions in the well-filled grains harvested. In the Cramer method, the per cent yield loss was derived by dividing the difference between the means for well-filled grains in healthy and diseased by the potential yield, i.e., actual yield from healthy plants to which the difference was added. The yield loss calculated by the Cramer method was 17–31% for BLB epidemics in all four districts. Partially filled grains and chaff/hill showed minor variations, but their influence on grain harvest was negligible. In the representational farms investigated, there was a highly significant and negative relationship between well-filled grains/hill and BLB severity. The yield loss estimated on the attainable yield using regression models ranged from 31 to 44%. In the linear models, the coefficient of determination R 2 ranged from 0.61 to 0.68 on three farms, and was 0.21 and 0.39 on two other farms. The Cramer and regression methods gave similar estimates for loss of potential yield in only one farm, located in Karnal district. In calculating production loss, the actual production in the entire district is usually taken, assuming damage from disease at all farms, and this leads to an over-estimation. A modification was made to consider disease prevalence as a percentage of farms with disease above the economic threshold level in a district. This adjustment enabled the production loss estimate to be tailored to the actual area damaged by the pathogen. By multiplying district production estimates by the disease prevalence (%), production loss in a district was precisely derived. In BLB epidemics, the most conservative estimates for production yield losses in districts were 3–16%. The production losses during the four epidemics were considerably different, ranging from 92,000 to 105,000 tons in Nellore, 30,000 to 36,000 tons in West Godavari, and 46,000 tons in Karnal to 22,000 tons in Rangareddy district.

Bacterial Leaf Blight on shrunken-2 Sweet Corn.

Severity of bacterial leaf blight (BLB, caused by Acidovorax avenae subsp. avenae) on shrunken-2 (sh2) sweet corn hybrids grown in BLB-conducive environments and sporadic outbreaks of BLB in recent years warranted evaluations of the potential for this disease to cause economic losses. BLB symptoms on 122 sh2 hybrids, 30 sh2 inbred lines, and 29 crosses of the inbreds and the effects of BLB on yield (ear weight and marketable ears) were evaluated in 1994 and 1996. BLB severity ratings for 122 hybrids averaged 3.3 and 3.7 (on a scale of 1 to 9) in 1994 and 1996, respectively. Hybrid means ranged from 1.8 to 5.5 in 1994 and from 1.9 to 5.7 in 1996, with Bayesian LSD values of 1.20 and 1.22, respectively. There were no differences in BLB ratings among hybrids with yellow, white, or bicolored kernels. Severity of symptoms on 30 sh2 inbreds ranged from 1.5 to 5.7, whereas the reactions of 29 crosses of the inbreds ranged from 1.9 to 5. The slope coefficient of the regression of crosses on mid-parent values was not different from 1. Thus, mid-parent values gave a good indication of severity of BLB symptoms on crosses, with the exception of a few crosses that tended to be more severely infected than expected based on mid-parent values. Ear weights and number of marketable ears differed among hybrids in the 1994 trial, but there was no significant effect of BLB treatments on either of these measures of yield. In 1996, ear weights in inoculated plots were 10 and 15% lower than those from noninoculated plots for 2 of 12 hybrids. Despite moderately severe foliar symptoms, BLB did not affect yield substantially in these trials even among hybrids with the most susceptible reactions.

Influence of Temperature and Light on Severity of Bacterial Blight of Corn, Oats, and Wheat

SCHAAD, N. W., D. R. SUMNER, and G. 0. WARE. 1980. Influence of temperature and light on severity of bacterial blight of corn, oats, and wheat. Plant Disease 64:481-483. Two experiments using five strains of Pseudomonas avenae and five day/night temperature regimens were conducted to determine the influence of temperature and light on the severity of bacterial leaf blight of corn, wheat, and oats. The first experiment showed that light had no effect on lesion development. In the second experiment, plant growth data for corn and wheat were recorded also. The effects of temperature on blight severity differed with the host. On corn, lesion development was not affected by temperature but plant growth was significantly reduced at the three intermediate temperature regimens. Average lesion size was significantly greater with strain C-71 than with strain 19860 at temperatures of 22/ 14 and 18/14 C but not at 30/ 26, 30/22, or 22/18 C. On oats, P. avenae strain significantly affected lesion development and disease was generally more severe at higher temperatures. On wheat, blight symptoms were generally more severe at higher temperatures but P. avenae strain had no significant effect. Under Georgia conditions, bacterial blight should be less severe in oats and wheat sown late in the fall season when the temperature is cooler. With corn, plant growth should be less reduced when the mean evening temperature is > 22 C. Strains of P. avenae should affect the severity of bacterial leaf blight of corn and oats but not of wheat. Bacterial leaf blight of corn, caused by Pseudomonas avenae (4), has been observed sporadically in corn fields in southern Georgia for several years. Severe outbreaks generally occur in late May and early June after periods of overcast and wet weather (7). Mean temperatures in south Georgia during this period are usually 18-24 C (7). The first symptoms are usually observed in early May when corn plants are 0.8-1 m tall. Although bacterial leaf blight of corn has been known for many years (2,8), little information is available on the effects of light and temperature on disease severity. Johnson et al (2) observed in a greenhouse that symptoms were abundant at 29-35 C, few at 24 C, and infrequent or lacking at 21 C. There are no reports of any observations on the effects of temperature on disease severity in oats and wheat. The objective of our study was to determine the influence of temperature and light on the severity of bacterial blight of corn, oats, and wheat. We wanted to determine if temperature and/ or light could also be used to predict disease occurrence. Experiments were done in environ

Relationship Between Nitrogen Fertilization, Bacterial Leaf Blight Severity, and Yield of Rice

Relationship Between Nitrogen Fertilization, Bacterial Leaf Blight Severity, and Yield of Rice