scholarly journals A review on important maize diseases and their management in Nepal

2015 ◽  
Vol 1 (1) ◽  
pp. 28-52 ◽  
Author(s):  
Subash Subedi
Keyword(s):  
Disease Management ◽  
Disease Incidence ◽  
Bacterial Species ◽  
Gray Leaf Spot ◽  
Leaf Blight ◽  
Brown Spot ◽  
Steady Increase ◽  
Ear Rot ◽  
Loss Assessment ◽  
Maize Crop

In Nepal, maize ranks second after rice both in area and production. In recent years, maize area and production has shown a steady increase, but productivity has been low (2.46 t/ha). The major maize producing regions in Nepal are mid hill (72.85%), terai (17.36%) and high hill (9.79%) respectively. A literature review was carried out to explore major maize diseases and their management in Nepal. The omnipresent incidence of diseases at the pre harvest stage has been an important bottleneck in increasing production. Till now, a total of 78 (75 fungal and 3 bacterial) species are pathogenic to maize crop in Nepal. The major and economically important maize diseases reported are Gray leaf spot, Northern leaf blight, Southern leaf Blight, Banded leaf and sheath blight, Ear rot, Stalk rot, Head smut, Common rust, Downy mildew and Brown spot. Information on bacterial and virus diseases, nematodes and yield loss assessment is also given. Description of the major maize diseases, their causal organisms, distribution, time and intensity of disease incidence, symptoms, survival, spreads, environmental factors for disease development, yield losses and various disease management strategies corresponded to important maize diseases of Nepal are gathered and compiled thoroughly from the available publications. Concerted efforts of NARC commodity programs, divisions, ARS and RARS involving research on maize pathology and their important outcomes are mentioned. The use of disease management methods focused on host resistance has also been highlighted.Journal of Maize Research and Development (2015) 1(1):28-52DOI: http://dx.doi.org/10.5281/zenodo.34292

scholarly journals Status of Rice Brown Spot (Helminthosporium oryza) Management in India: A Review

2021 ◽  
Author(s):  
M. Surendhar ◽  
Y. Anbuselvam ◽  
J. Johnny Subakar Ivin
Keyword(s):  
Disease Management ◽  
Yield Loss ◽  
Disease Incidence ◽  
Control Measures ◽  
Brown Spot ◽  
Strong Impact ◽  
Management Protocol ◽  
Current Scenario ◽  
Helminthosporium Oryzae ◽  
Historic Significance

Rice is one of the most widely consumed staple food for more than half of the population in the world. Brown spot caused by Helminthosporium oryzae accounts for 5% yield loss worldwide annually. Adversely affected fields show yield loss as high as 45%. The present study focuses on the several management aspects that are currently used to curb out the disease incidence and measures to be taken in near future for designing effective disease management protocol. The disease is of historic significance and a devasting outbroke in the Bengal Province during 1943 ended as the Great Bengal Famine resulting in starvation and an estimated demise of 2.1 to 3 million people. Brown spot is still devastating on looking the present scenario of damage to rice. Different approaches have been adopted ranging from the use of brown spot resistant rice cultivars, chemical ameliorations and biological control measures for the management of the disease. But, still the disease seems to be chronic and adverse in the current scenario. In this review, we have highlighted epidemiology, control measures practiced and several quantitative and qualitative gaps with respect to disease management, which if rectified, would lead to a strong impact on crop disease control and the sustainable Rice production that are pertinent to the present situation of farmers.

scholarly journals Silicon-Induced Systemic Defense Responses in Perennial Ryegrass Against Infection by Magnaporthe oryzae

2015 ◽  
Vol 105 (6) ◽  
pp. 748-757 ◽  
Author(s):  
Alamgir Rahman ◽  
Christopher M. Wallis ◽  
Wakar Uddin
Keyword(s):  
Disease Management ◽  
Perennial Ryegrass ◽  
Magnaporthe Oryzae ◽  
Leaf Spot ◽  
Calcium Silicate ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Defense Responses ◽  
Gray Leaf Spot ◽  
Integrated Disease Management

Sustainable integrated disease management for gray leaf spot of perennial ryegrass may involve use of plant defense elicitors with compatible traditional fungicides to reduce disease incidence and severity. Silicon (Si) has previously been identified as a potential inducer or modulator of plant defenses against different fungal pathogens. To this end, perennial ryegrass was inoculated with the causal agent of gray leaf spot, Magnaporthe oryzae, when grown in soil that was nonamended or amended with three different levels of calcium silicate (1, 5, or 10 metric tons [t]/ha). When applied at a rate of 5 t/ha, calcium silicate was found to significantly suppress gray leaf spot in perennial ryegrass, including a significant reduction of disease incidence (39.5%) and disease severity (47.3%). Additional studies observed nonpenetrated papillae or cell-wall appositions harboring callose, phenolic autofluorogens, and lignin-associated polyphenolic compounds in grass grown in the Si-amended soil. Regarding defense-associated enzyme levels, only following infection did grass grown in Si-amended soil exhibit greater activities of peroxidase and polyphenol oxidase than equivalent inoculated control plants. Also following infection with M. oryzae, grass levels of several phenolic acids, including chlorogenic acid and flavonoids, and relative expression levels of genes encoding phenylalanine ammonia lyase (PALa and PALb) and lipoxygenase (LOXa) significantly increased in Si-amended plants compared with that of nonamended control plants. These results suggest that Si-mediated increase of host defense responses to fungal pathogens in perennial ryegrass has a great potential to be part of an effective integrated disease management strategy against gray leaf spot development.

scholarly journals Evaluation of BSPcast Disease Warning System in Reduced Fungicide Use Programs for Management of Brown Spot of Pear

Plant Disease ◽  
2000 ◽  
Vol 84 (6) ◽  
pp. 631-637 ◽  
Author(s):  
I. Llorente ◽  
P. Vilardell ◽  
R. Bugiani ◽  
I. Gherardi ◽  
E. Montesinos
Keyword(s):  
Disease Management ◽  
Disease Incidence ◽  
Warning System ◽  
Growing Season ◽  
Infection Risk ◽  
Brown Spot ◽  
Forecasting Model ◽  
Advisory System ◽  
Application Programs ◽  
Protection Period

A forecasting model (BSPcast) developed for prediction of brown spot (Stemphylium vesicarium) of pear was evaluated as an advisory system for reduced fungicide use in disease management programs. Eleven trials were performed during 1995, 1996, and 1997 in five orchards in two different climatic areas in Catalunya (Spain) and Emilia-Romagna (Italy). Values of 3-day cumulative daily infection risk (CR) provided by the model were used to determine risk periods during the growing season of pear and were taken as thresholds to schedule fungicide sprays. The fungicide application programs tested using the model consisted of guided schedules with CR action thresholds of 0.4, 0.5, or 0.6, and fixed sprays following a standard commercial schedule. In nine out of 10 trials, no significant differences were observed in disease incidence on fruit at harvest between the fixed-spray commercial schedule and guided sprays using thresholds of 0.4 or 0.5. The average savings in number of fungicide sprays applied using BSPcast compared with the fixed-spray schedule were 20 to 70% when using fungicides with a 15-day protection period (kresoxim-methyl or procymidone) and ranged from 20 to 50% when using a fungicide with a 7-day protection period (thiram).

scholarly journals The Utility of the Upcoming HyspIRI’s Simulated Spectral Settings in Detecting Maize Gray Leafy Spot in Relation to Sentinel-2 MSI, VENµS, and Landsat 8 OLI Sensors

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 846
Author(s):  
Mbulisi Sibanda ◽  
Onisimo Mutanga ◽  
Timothy Dube ◽  
John Odindi ◽  
Paramu L. Mafongoya
Keyword(s):  
Food Security ◽  
Precision Agriculture ◽  
Leaf Spot ◽  
Gray Leaf Spot ◽  
Economic Losses ◽  
Leaf Spot Disease ◽  
Landsat 8 ◽  
Landsat 8 Oli ◽  
Maize Crop ◽  
Sentinel 2

Considering the high maize yield loses caused by incidences of disease, as well as incomprehensive monitoring initiatives in crop farming, there is a need for spatially explicit, cost-effective, and consistent approaches for monitoring, as well as for forecasting, food-crop diseases, such as maize Gray Leaf Spot. Such approaches are valuable in reducing the associated economic losses while fostering food security. In this study, we sought to investigate the utility of the forthcoming HyspIRI sensor in detecting disease progression of Maize Gray Leaf Spot infestation in relation to the Sentinel-2 MSI and Landsat 8 OLI spectral configurations simulated using proximally sensed data. Healthy, intermediate, and severe categories of maize crop infections by the Gray Leaf Spot disease were discriminated based on partial least squares–discriminant analysis (PLS-DA) algorithm. Comparatively, the results show that the HyspIRI’s simulated spectral settings slightly performed better than those of Sentinel-2 MSI, VENµS, and Landsat 8 OLI sensor. HyspIRI exhibited an overall accuracy of 0.98 compared to 0.95, 0.93, and 0.89, which were exhibited by Sentinel-2 MSI, VENµS, and Landsat 8 OLI sensor sensors, respectively. Furthermore, the results showed that the visible section, red-edge, and NIR covered by all the four sensors were the most influential spectral regions for discriminating different Maize Gray Leaf Spot infections. These findings underscore the potential value of the upcoming hyperspectral HyspIRI sensor in precision agriculture and forecasting of crop-disease epidemics, which are necessary to ensure food security.

scholarly journals Variation of rhizosphere microbial community in continuous mono-maize seed production

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yunchen Zhao ◽  
Wenjiang Fu ◽  
Changwei Hu ◽  
Guangquan Chen ◽  
Zhanwen Xiao ◽  
...  
Keyword(s):  
Microbial Community ◽  
Seed Production ◽  
Disease Incidence ◽  
Bacterial Species ◽  
Curvularia Lunata ◽  
Continuous Cropping ◽  
Maize Seed ◽  
Bacterial Phyla ◽  
Soil Microbial ◽  
Pathogen Invasion

AbstractSoil microbe is crucial to a healthy soil, therefore its diversities and abundances under different conditions are still need fully understand.The aims of the study were to characterize the community structure and diversity of microbe in the rhizosphere soil after continuous maize seed production, and the relationship between the disease incidence of four diseases and the variation of the rhizosphere microbe. The results showed that different fungal and bacterial species were predominant in different cropping year, and long-term maize seed production had a huge impact on structure and diversity of soil microbial. Ascomycota and Mortierellomycota were the dominant fungal phyla and Mortierella and Ascomycetes represented for a large proportion of genus. A relative increase of Fusarium and Gibberella and a relative decrease of Mortierella, Chrysosporium, Podospora, and Chaetomium were observed with the increase of cropping year. Pathogenic Fusarium, Curvularia, Curvularia-lunata, Cladosporium, Gibberella-baccata, and Plectosphaerellaceae were over-presented and varied at different continuous cropping year, led to different maize disease incidence. Proteobacteria and Actinobacteria ranked in the top two of all bacterial phyla, and genus Pseudarthrobacter, Roseiflexus and RB41 dominated top 3. Haliangium and Streptomyces decreased with the continuous cropping year and mono-cropping of maize seed production increased disease incidence with the increase of cropping year, while the major disease was different. Continuous cropping of maize seed production induced the decrease of protective microbe and biocontrol genera, while pathogenic pathogen increased, and maize are in danger of pathogen invasion. Field management show great effects on soil microbial community.

Phylogeny and identification of Pantoea species associated with bulb rot and bacterial leaf blight of onion crops in Uruguay

Plant Disease ◽  
2021 ◽  
Author(s):  
Stefanie De Armas ◽  
Guillermo Alesio Galván ◽  
María Inés Lapaz ◽  
Pablo González-Barrios ◽  
Esteban Vicente ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Complex Disease ◽  
Bacterial Species ◽  
Housekeeping Genes ◽  
Leaf Blight ◽  
Rrna Gene ◽  
Breeding Lines ◽  
Gene Sequence Analysis ◽  
Bulb Rot ◽  
Physiological Tests

Onion is among the most consumed vegetables in Uruguay, grown in the Northwestern and Southern regions of the country. The onion supply presents interannual variations associated with significant postharvest losses, mainly caused by bacterial rots. Besides bulb rotting, onion leaf lesions as well as infections on seed-stalks during seed production may be devastating for some varieties under conducive conditions. This research aimed to identify the causal agents of bulb rots and leaf blight of onion crops in Uruguay. Symptomatic bulbs, seeds-stalks and leaves were collected from commercial fields from 2015 to 2020. Bacterial colonies were isolated and identified at genera level using physiological tests and 16S rRNA gene sequence analysis. A collection of 59 Pantoea spp. isolates was obtained (11 from bulbs and 48 from leaves and seeds-stalks). Multilocus sequence analysis (MLSA) using four housekeeping genes (rpoB, gyrB, leuS and fusA) allowed the assignment of the isolates to five Pantoea species: P. ananatis, P. agglomerans, P. allii, P. eucalypti and P. vagans. The last two species were not previously reported as onion pathogens elsewhere. The ability to cause disease symptoms was tested by leaf inoculation and red onion scale assays. Pantoea ananatis isolates showed the highest aggressiveness in both assays. Specific isolates from P. allii (MAI 6022), P. eucalypti (MAI 6036), P. vagans (MAI 6050), and Pantoea sp. (MAI 6049) ranked the second in aggressiveness on onion leaves, while only three isolates belonging to P. eucalypti (MAI 6036 and MAI 6058) and P. agglomerans (MAI 6045) exhibited the same scale clearing phenotype as P. ananatis. Leaf inoculation assays were also performed on a set of eight onion cultivars and breeding lines. Overall, P. ananatis MAI 6032 showed the highest aggressiveness in all tested cultivars, followed by P. eucalypti MAI 6036. The presence of new reported bacterial species leads to complex disease management and highlights the need for further studies on virulence factors and the epidemiology of these pathogens.

Alternaria spp. associated with leaf blight of maize in Heilongjiang Province, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xi Xu ◽  
Li Zhang ◽  
Xilang Yang ◽  
Hanshui Cao ◽  
Jingjing Li ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Population Expansion ◽  
Leaf Blight ◽  
Economic Losses ◽  
Heilongjiang Province ◽  
Maize Leaves ◽  
Alternaria Species ◽  
Alternaria Sp

Maize is a major economic crop worldwide. Maize can be infected by Alternaria species causing leaf blight that can result in significant economic losses. In this study, 168 Alternaria isolates recovered from symptomatic maize leaves were identified based on morphological characteristics, pathogenicity, and multi-locus sequence analyses of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer of ribosomal DNA (rDNA ITS), the RNA polymerase II second largest subunit (RPB2), and histone 3 (HIS3). Maize isolates grouped to four Alternaria species including Alternaria tenuissima, A. alternata, A. burnsii, and Alternaria sp. Notably, A. tenuissima (71.4%) was the most prevalent of the four isolated species, followed by A. alternata (21.5%), Alternaria sp. (4.1%), and A. burnsii (3.0%). Pathogenicity tests showed that all four Alternaria species could produce elliptic to nearly round, or strip lesions on leaves of maize, gray white to dry white in the lesions center and reddish brown in the edge. The average disease incidence (58.47%) and average disease index (63.55) of maize leaves inoculated with A. alternata were significantly higher than levels resulting from A. tenuissima (55.28% and 58.49), Alternaria sp. (55.34% and 58.75), and A. burnsii (56% and 55). Haplotype analyses indicated that there were 14 haplotypes of A. tenuissima and 5 haplotypes of A. alternata in Heilongjiang province and suggested the occurrence of a population expansion. Results of the study showed that Alternaria species associated with maize leaf blight in Heilongjiang province are more diverse than those have been previously reported. This is the first report globally of A. tenuissima, A. burnsii, and an unclassified Alternaria species as causal agents of leaf blight on maize.

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