scholarly journals Southern leaf blight disease severity is correlated with decreased maize leaf epiphytic bacterial species richness and the phyllosphere bacterial diversity decline is enhanced by nitrogen fertilization

2014 ◽  
Vol 5 ◽  
Author(s):  
Heather C. Manching ◽  
Peter J. Balint-Kurti ◽  
Ann E. Stapleton
2021 ◽  
Vol 23 (1) ◽  
pp. 54-59
Author(s):  
SANTOSH KUMAR ◽  
MD. NADEEM AKHTAR ◽  
SANTOSH KUMAR ◽  
MAHESH KUMAR ◽  
TRIBHUWAN KUMAR

Weather parameters play a pivotal role in the infection process and spread of pathogen. It also influences the expression of susceptibility/resistance of the host plant during post-infection phases. Therefore, an experiment was conducted for two consecutive cropping seasons (2018 &2019) to study the influence of weather parameters such as temperature, humidity, rainfall and wind direction on the emergence of alternaria leaf blight of makhana in Koshi region of Bihar. Maximum per cent disease severity of alternarialeaf blightwas observed during the peak monsoon months (June to August). Highest disease severity of leaf blight (14.80% & 15.7%) was observed in the mid June during crop season, 2018 and 2019. High temperature (36.9oC & 38.1oC), and relative humidity (94% & 96.4%) of both the year 2018 and 2019 were found correlated with higher severity to alternaria leaf blight. Similarly average HTR values (3.1) were also found correlated with the average high temperature and relative humidity of both years (2018 and 2019) in terms of severity of leaf blight disease. Maximum temperatures, relative humidity and rainfall exhibited strong positive linear relationship and influenced the occurrence of alternaria leaf blight disease significantly. We also developed a geo-phytopathological model for the prediction of alternaria leaf blight disease of makhana on the basis of congenial mean temperature and relative humidity.


Author(s):  
Mandah Cicelia Takor ◽  
Ekwa Yawa Monono ◽  
Ojong Agbor Ntane ◽  
Jemimah Evenye Ngale ◽  
Lum A. Fontem

Taro leaf blight (TLB), a major disease of taro plant caused by Phytophthora colocasiae, a pseudo-fungus, that occurs in many taro producing areas, especially in the South West of Cameroon. A Survey was conducted to assess farmers’ knowledge, as well as to determine the incidence and the severity of the disease in taro fields. Structured questionnaires were administered in selected locations (Bokova, Ekona, Muea, Mile 16, Mutengene, and Likomba) of taro production. Two farms were selected with two quadrats of 64 m2 each were carved to assess disease incidence and severity on taro. The number of plants infected with taro leaf blight were counted and the area of the affected leaves measured was used to evaluate the disease incidence and disease severity. Data collected were subjected to ANOVA for complete randomized design and the means were compared using Tukey test at 0.05 probability levels. The results revealed that most of the farmers could identify the disease while practicing cultural methods in controlling the disease. The results also revealed significant differences (p = 0.001) in disease incidence and disease severity in all the localities, with Mile 16 showing the highest percentage mean of 96.53% and 85.59%, respectively. The severity scored showed high infection range of 3 – 3.95 in all locations except in Likomba (2.60).  It could be concluded from the results that there were high prevalence of taro leaf blight disease in Fako Division. Good management strategies are therefore required to control Taro leaf blight and improve taro production in the area.


2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Hyat Mahmud

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.


Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 652
Author(s):  
Wannaporn Thepbandit ◽  
Narendra Kumar Papathoti ◽  
Jayasimha Rayalu Daddam ◽  
Kanjana Thumanu ◽  
Supatcharee Siriwong ◽  
...  

The present study was to investigate the application and mechanism of salicylic acid (SA) as SA-Ricemate for the control of leaf blight disease using a Synchrotron Radiation-based Fourier-Transform Infra-Red (SR-FTIR) microspectroscopy and docking studies. After treating rice plants cv. KDML 105 with SA-Ricemate, the leaves were inoculated with Xanthomonas oryzae pv. oryzae, the causal agent of leaf blight, and disease severity were assessed. The leaves were also used to detect changes in endogenous SA content. The results indicated that SA-Ricemate, as an activated compound, reduced disease severity by 60% at three weeks post-inoculation and increased endogenous content by 50%. The SR-FTIR analysis of changes in the mesophyll of leaves (treated and untreated) showed that the groups of lipids, pectins, and proteins amide I and amide II occurred at higher values, and polysaccharides were shown at lower values in treated compared to untreated. Besides, docking studies were used to model a three-dimensional structure for Pathogenesis-related (PR1b) protein and further identify its interaction with SA. The results showed that ASP28, ARG31, LEU32, GLN97, and ALA93 are important residues that have strong hydrogen bonds with SA. The docking results showed that SA has a good interaction, confirming its role in expression.


Bio-Research ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 1286-1296
Author(s):  
Faustina Njideka Ugwuja ◽  
Chiemeka Nwakaego Onaebi ◽  
Nneka Virginia Chiejina ◽  
Kelvin Ikechukwu Ugwuoke

Leaf-blight disease of Colocasia caused by Phytophthora colocasiae Raciborski has been a serious impediment to cocoyam production in Nigeria. Disease severity and susceptibility of the two most cultivated local varieties “Ugwuta” (Colocasia esculenta var. antiquorum) and “Nkashi Colocasia esculenta var. esculenta) were investigated. Disease severity was visually estimated as the percentage leaf surface affected by blight, lesion or lesion-related chlorosis for each leaf of a plant using a seven-point scale of 0, 5, 10, 25, 50, 75 and 100% in three locations: Ede-Oballa, Nsukka Urban and Obukpa. Susceptibility was assessed on 2 months old potted plants of each variety inoculated with a 7-day old culture of P. colocasiae. Diameters of lesions on inoculated leaves were recorded from the 3rd - 8th day after inoculation.  Data on severity were subjected to ANOVA and susceptibility of the varieties was compared with t-test. Results revealed significant LSD=4.96 (0.05) and varying degrees of leaf blight severity among varieties and locations. Variety antiquorum had significantly higher severities of 42.08, 46.40 and 47.42% at Ede-Oballa, Nsukka Urban and Obukpa respectively, compared to 34.85, 36.55 and 28.19% recorded by var. esculenta at these locations, respectively. Similarly, var. antiquorum had greater lesion diameter ranging from 0.65±0.07 cm - 3.70±0.14 cm and average diameter of 2.4±0.16cm compared to var. esculenta which had 0.41±0.14cm - 3.12±0.19 cm and average diameter of 1.80±0.16. This research has shown that varieties and locations affect the severity and susceptibility of Phytophthora leaf blight disease. This could be a guide to farmers having known that var. esculenta is less severe to Phytophthora leaf blight disease.


2014 ◽  
Vol 6 (1) ◽  
pp. 95-100
Author(s):  
Gokil Prasad Gangwar ◽  
A. P. Sinha

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.


2017 ◽  
Vol 15 (1) ◽  
pp. 10-18
Author(s):  
MAH Khan ◽  
I Hossain ◽  
MU Ahmad ◽  
MSM Chowdhury

Leaf blight of seven varieties of litchi caused by Pseudomonas syringae pv. syringae was surveyed in the nurseries of major litchi growing areas in Bangladesh viz. Rajshahi, Dinajpur, Rangpur, Mymensingh and Khagrachari. The mean level of incidence and severity were 8.58 and 7.88% in Rajshahi, 9.88 and 8.88% in Dinajpur, 8.44 and 7.76% in Rangpur, 6.50 and 6.18% in Mymensingh and 9.00 and 7.98% in Khagrachari. Incidence and severity of bacterial leaf blight disease of litchi varied significantly depending on weather conditions. Correlation studies revealed that bacterial leaf blight disease of litchi seedlings were positively correlated with temperature, rainfall and relative humidity, where temperature and rainfall was the major factor to the variations of both incidence and severity. Antibiotic sensitivity test revealed that among fifteen isolates, most of the isolates of P. syringae pv. syringae collected from litchi were sensitive to Gentamycin and Erythromycin. Under net house condition, six different treatments (i) Gentamycin @ 0.05%, (ii) Erythromycin @ 0.05%, (iii) Doxycycline @ 0.05%,(iv) Copper sulphate @ 0.05%, (v) BAU-Biofungicide @ 2% and (vi) Control were used for controlling bacterial leaf blight of litchi (Variety: China-3). BAU-Biofungicide was found to be superior in controlling bacterial leaf blight of litchi that reduced 33.64% disease incidence and 60.77 % disease severity in 2010-11 and 63.76% disease incidence and 61.40 % disease severity in 2011-12 over control when applied as foliar spray @ 2% followed by Copper sulphate (0.05%) and Erythromycin (0.05%).The Agriculturists 2017; 15(1) 10-18


Author(s):  
P. B. Magar ◽  
G. B. Khatri-Chhetri ◽  
S. M. Shrestha ◽  
T. R. Rijal

A study was conducted during June to September, 2012, in the field at National Maize Research Program, Rampur, Chitwan, Nepal with the objective of screening 20 maize genotypes against southern leaf blight caused by Bipolaris maydis. Experiment was laid out in a randomized complete block design with three replications. Disease scoring was done as percentage of leaf area infected on individual plant at 7 days intervals starting from 50 days after sowing, for 6 times, and disease severity and mean AUDPC were calculated and yield recorded. Among the tested genotypes, there was variation in disease severity and mean AUDPC values. Disease severity was maximum on Yellow Popcorn (51.67%) and least on RML-32/RML-17 (7.27%). Based on mean AUDPC values, RML-32/RML-17 (20.53) appeared most resistant, followed by RML-4/NML-2 (23.66) and RML-4/RML-17 (25.90), while Yellow Popcorn (136.9) was found the most susceptible. Highest grain yield (4.90 t/ha) was also recorded on RML-32/RML-17 and least (2.49 t/ha) on Yellow Popcorn. Therefore the genotypes RML-32/RML-17, RML-4/NML-2 and RML-4/RML-17 could be used as the resistant varieties and source of resistance to southern leaf blight for varietal development of maize.Journal of the Institute of Agriculture and Animal Science.Vol. 33-34, 2015, Page: 115-122


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