scholarly journals Spatial and Temporal Analyses of Bacterial Blight of Onion Caused by Xanthomonas axonopodis pv. allii

2004 ◽  
Vol 94 (2) ◽  
pp. 138-146 ◽  
Author(s):  
P. Roumagnac ◽  
O. Pruvost ◽  
F. Chiroleu ◽  
G. Hughes
Keyword(s):  
Bacterial Blight ◽  
Disease Incidence ◽  
Severe Disease ◽  
Spatial Dynamics ◽  
Seed Transmission ◽  
Contamination Rate ◽  
Xanthomonas Axonopodis ◽  
Initial Inoculum ◽  
Incidence Data ◽  
Disease Patterns

Bacterial blight of onion is a severe disease, which emerged over the past decade in several onion-producing areas. This disease currently is observed in both the Old and New Worlds. Although the causative agent, Xanthomonas axonopodis pv. allii, is potentially seedborne, seed transmission and significance of seedborne initial inoculum for the development of bacterial blight of onion previously has not been assessed. This article describes experimental work designed to evaluate the biological importance of seedborne X. axonopodis pv. allii as an initial inoculum source, and examine the temporal and spatial dynamics of the disease. Over 3 years, outbreaks of bacterial blight of onion always were induced in experimental plots sown with naturally contaminated seed lots, with a contamination rate determined as 0.04%. Analyses of disease patterns indicated a likely seedborne origin for the inoculum associated with the early stages of epidemics. Spatial analyses performed with several statistical methods indicated aggregated patterns of disease incidence data. Primary foci enlarged over time, and a few distinct secondary foci sometimes were established after occurrence of wind-driven rains (with gusts up to 15 m s-1). Distances between primary and secondary foci ranged from less than 1 m (satellite foci) to 25 m. It remains possible that longdistance dispersal of inoculum was at least partly involved in the later stages of epidemics.

Comparison of Seed Transmission and Survival of Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans in Common Bean Seeds

2013 ◽  
Vol 14 (1) ◽  
pp. 41 ◽  
Author(s):  
Y. He ◽  
G. P. Munkvold
Keyword(s):  
Phaseolus Vulgaris ◽  
Common Bean ◽  
Bacterial Blight ◽  
Disease Incidence ◽  
Seed Transmission ◽  
Common Bacterial Blight ◽  
Phaseolus Vulgaris L ◽  
Transmission Frequency ◽  
Xanthomonas Axonopodis ◽  
Seed Health

Xanthomonas axonopodis pv. phaseoli (Smith) Vauterin (Xap) and Xanthomonas fuscans subsp. fuscans Schaad et al. (Xff) cause indistinguishable symptoms known as common bacterial blight of bean (Phaseolus vulgaris L.). These results confirm a higher disease incidence and seed transmission frequency of Xff compared to Xap and reinforce the need for seed health tests that can differentiate the two species. Accepted for publication 21 August 2013. Published 23 September 2013.

scholarly journals Aerial Photography Used for Spatial Pattern Analysis of Late Blight Infection in Irrigated Potato Circles

2003 ◽  
Vol 93 (7) ◽  
pp. 805-812 ◽  
Author(s):  
Dennis A. Johnson ◽  
J. Richard Alldredge ◽  
Philip B. Hamm ◽  
Bruce E. Frazier
Keyword(s):  
Late Blight ◽  
Aerial Photography ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Disease Incidence ◽  
Aerial Photographs ◽  
Spatial Pattern Analysis ◽  
Initial Inoculum ◽  
Disease Patterns ◽  
Commercial Potato

Spatial and temporal dynamics of late blight were investigated from color, infrared aerial photographs of five commercial potato fields in the Columbia Basin during epidemics in 1993, 1995, and 1998. Aerial photographs were taken one to four times at 6- to 21-day intervals. Photographs were scanned and pixels, representing approximately 1 m2 in the field, were used in the analysis. Late blight-infected plants were aggregated as indicated by runs analysis. Significant z-tests were computed for four directions during each sampling date in each of the five fields. Absolute z-values for runs analysis increased, indicating increasing aggregation in the four directions, as disease incidence increased in the early and midphases of the epidemics in each field. Variograms indicated the existence of autocorrelation among infected plants in four directions; the range of influence increased as disease incidence increased except at the highest levels of disease. Late blight was observed to spread in fields as foci. Late blight foci enlarged in size, produced distinct daughter foci, and coalesced. A field where initial inoculum likely originated from infected seed tubers exhibited less initial aggregation than the other fields, perhaps due to a different source of primary inoculum. Aerial photography coupled with spatial analyses of late blight-infected plants was an effective technique to quantitatively assess disease patterns in relatively large fields and was useful in quantifying an intensification of aggregation during the epidemic process on a large scale.

scholarly journals Quantitative and Molecular Epidemiology of Bacterial Blight of Onion in Seed Production Fields

2006 ◽  
Vol 96 (12) ◽  
pp. 1345-1354 ◽  
Author(s):  
L. Humeau ◽  
P. Roumagnac ◽  
Y. Picard ◽  
I. Robène-Soustrade ◽  
F. Chiroleu ◽  
...  
Keyword(s):  
Seed Production ◽  
Binomial Distribution ◽  
Bacterial Blight ◽  
Disease Incidence ◽  
Aflp Analysis ◽  
Data Sets ◽  
Spatial Dependency ◽  
Nested Polymerase Chain Reaction ◽  
Incidence Data ◽  
Polymerase Chain

Onion, a biennial plant species, is threatened by the emerging, seed-borne, and seed-transmitted Xanthomonas axonopodis pv. allii. Bacterial blight epidemics were monitored in seed production fields over two seasons. Temporal disease progress was different between the two seasons, with final incidence ranging from 0.04 to 0.06 in 2003 and from 0.44 to 0.61 in 2004. The number of hours with temperatures above 24°C was the best descriptor for predicting the number of days after inoculation for bacterial blight development on inoculated plants. Fitting the β-binomial distribution and binary power law analysis indicated aggregated patterns of disease incidence data. The β-binomial distribution was superior to the binomial distribution for 97% of the examined data sets. Spatial dependency ranged from 5.9 to 15.2 m, as determined by semivariance analysis. Based on amplified fragment length polymorphism (AFLP) analysis, it was concluded that plots predominantly were infected by the inoculated haplotype. A single other haplotype was identified by AFLP in all plots over the 2 years, and its detection in the field always followed wind-driven rains. X. axonopodis pv. allii-contaminated seed were detected by semiselective isolation and a nested polymerase chain reaction assay at levels up to 0.05% when final disease incidence was 0.61. Contaminated seed originated from both diseased and asymptomatic plants.

scholarly journals Association of common bacterial blight (Xanthomonas axonopodis pv. phaseoli) epidemics with agro ecological factors in Southwestern Ethiopia

2021 ◽  
Vol 11 (1) ◽  
pp. 74-83
Author(s):  
W Adila ◽  
H Terefe ◽  
A Bekele
Keyword(s):  
Common Bean ◽  
Disease Severity ◽  
Crop Rotation ◽  
Weed Management ◽  
Bacterial Blight ◽  
Disease Incidence ◽  
Ecological Factors ◽  
Common Bacterial Blight ◽  
Xanthomonas Axonopodis ◽  
Southwestern Ethiopia

Common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli, is an economically important disease of common bean and causes significant yield losses in Ethiopia. A field survey was conducted to understand the spatial distribution, relative importance and association of common bacterial blight epidemics with agro-ecological factors in low and mid-land areas of Southwestern, Ethiopia, during the 2018-19 cropping season. A total 85 bean fields were assessed in four common bean growing districts. High diseases incidence and severity was recorded at Debub Ari (77.6 and 52.7%, respectively) while the lowest was from Male (38.5 and 28.0%, respectively). The associations between disease parameters and agro-ecological factors were analyzed using multiple logistic regression models. Agronomic practices including NPS fertilization, preceding crop, weed management and plant population had highly significant (P<0.0001) association with both disease incidence and severity. Also, altitude, seed source and cropping system significantly (P<0.05) influenced disease severity while cropping pattern showed significant (P<0.05) association with disease incidence in the reduced model. Higher mean disease severity (≥40%) had high probability of association with district, absence of NPS fertilization, poor weed management practice, and preceding crops, than their counter parts. Adequate NPS fertilization increases growth performance of the crop in turn decreases disease intensity, weed serve as alternate host for incoming inoculum and previous crops were source for inocula as well as crop rotation used as reduce inoculum load. Therefore, the present study showed that the disease is a major production constraint of common bean, and suggested proper nutrient and weed management practices, and crop rotation to reduce common bacterial blight in the study areas. Int. J. Agril. Res. Innov. Tech. 11(1): 74-83, June 2021

scholarly journals Seed-transmission of Cowpea mild mottle virus on several varieties of soybean in Indonesia

2021 ◽  
Vol 22 (10) ◽  
Author(s):  
Mimi Sutrawati ◽  
Sri Hendrastuti Hidayat ◽  
Gede Suastika ◽  
Bonny Purnomo Wahyu Sukarno ◽  
Ali Nurmansyah
Keyword(s):  
Field Experiment ◽  
Infection Rate ◽  
Disease Incidence ◽  
Seed Transmission ◽  
Test Method ◽  
Mottle Virus ◽  
Initial Inoculum ◽  
Transmitted Virus

Abstract. Sutrawati M, Hidayat SH, Suastika G, Sukarno BPW, Nurmansyah A. 2021. Seed-transmission of Cowpea mild mottle virus on several varieties of soybean in Indonesia. Biodiversitas 22: 4182-4185. Seeds and infected plants play important role as source of disease in the field for seed-transmitted virus, such as Cowpea mild mottle virus (CPMMV). Research was conducted to determine seed transmission nature of CPMMV on 10 soybean varieties based on growing on test method and dot immunobinding assay to confirm CPMMV infection. Field experiment was conducted to evaluate the efficiency of seed-transmitted CPMMV as the source of initial inoculum in the field. Soybean var. ‘Anjasmoro’ from 3 cultivation areas (Cianjur, Bogor, and Cirebon) was used for field experiment. Seed transmission of CPMMV was confirmed on soybean var. ‘Detam 2’, ‘Detam 3’, ‘Malika’, ‘Anjasmoro’, and ‘Argomulyo’; but was not found on ‘Detam 1’, ‘Detam 4’, ‘Wilis’, ‘Grobogan’, and ‘Dena 1’. The infection of CPMMV did not show symptom, either on the seedcoat and the unifoliolate leaves. Infection rate of CPMMV on seeds were relatively high, ranged between 27 to 86%. Disease incidence on var. ‘Anjasmoro’ from Cianjur, Cirebon, and Bogor varied from 32.9 to 75% and 57.9 to 81.3% in screenhouse and field experiment, respectivelly.

scholarly journals Geostical analysis of spatial dynamics of Citrus Variegated Chlorossis

2002 ◽  
Vol 27 (6) ◽  
pp. 599-604 ◽  
Author(s):  
SÉRGIO R. ROBERTO ◽  
PAULO R. S. FARIAS ◽  
ARMANDO BERGAMIN FILHO
Keyword(s):  
Sweet Orange ◽  
Disease Incidence ◽  
Spatial Dynamics ◽  
Spherical Model ◽  
Northern Region ◽  
Incidence Data ◽  
Semivariogram Analysis ◽  
Index Analysis ◽  
Best Fit ◽  
Kriging Maps

The spatial dynamics of Citrus Variegated Chlorosis (CVC) was studied in a five-year old commercial orchard of 'Valencia' sweet orange (Citrus sp.) trees, located in the northern region of the state of São Paulo, Brazil. One thousand trees were assessed in 25 rows of 40 trees, planted at 8 x 5 m spacing. Disease incidence data were taken beginning in March 1994 and ending in January 1996, at intervals of four to five months. Disease aggregation was observed through the dispersion index analysis (Ib), which was calculated by dividing the area into quadrants. CVC spatial dynamics was examined using semivariogram analysis, which revealed that the disease was aggregated in the field forming foci of 10 to 14 m. For each well-fitted model, a kriging map was created to better visualize the distribution of the disease. The spherical model was the best fit for the data in this study. Kriging maps also revealed that the incidence of CVC increased in periods during which the trees underwent vegetative growth, coinciding with greater expected occurrence of insect vectors of the bacterium in the field.

scholarly journals Cultivar and Spacing Effects on Transmission of Phytophthora parasitica in an Ebb-and-Flow Subirrigation System

Plant Disease ◽  
1997 ◽  
Vol 81 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Stephen S. Strong ◽  
Bridget K. Behe ◽  
C. Fred Deneke ◽  
Kira L. Bowen ◽  
Gary J. Keever
Keyword(s):  
Catharanthus Roseus ◽  
Disease Incidence ◽  
Severe Disease ◽  
Disease Development ◽  
Phytophthora Parasitica ◽  
Spacing Effects ◽  
Ebb And Flow

Phytophthora parasitica was transmitted within 6 weeks from vinca (Catharanthus roseus) plants growing in infested potting mix, on the drain end of ebb-and-flow benches, to plants in noninfested potting mix. Transmission of Phytophthora was very low when potting mix was not pasteurized. When potting mix was steam pasteurized, infection of plants, disease incidence, and severity increased with time and decreased with distance from plants in infested pots. The cultivar Pretty in Pink was more susceptible to infection by P. parasitica than cv. Peppermint Cooler, allowing more rapid and severe disease development as well as pathogen dissemination and transmission. Pot spacing did not significantly affect transmission of P. parasitica on an ebb-and-flow bench.

scholarly journals Common bacterial blight of bean: a model of seed transmission and pathological convergence

2021 ◽  
Author(s):  
Nicolas W. G. Chen ◽  
Mylène Ruh ◽  
Armelle Darrasse ◽  
Justine Foucher ◽  
Martial Briand ◽  
...  
Keyword(s):  
Bacterial Blight ◽  
Seed Transmission ◽  
Common Bacterial Blight

scholarly journals Effect of rejuvenation pruning on the growth, productivity and disease incidence in declining trees of pomegranate (Punica granatum L.) cv. Kandhari Kabuli

2018 ◽  
Vol 10 (1) ◽  
pp. 358-362
Author(s):  
D. P. Sharma ◽  
Niranjan Singh
Keyword(s):  
Bacterial Blight ◽  
Disease Incidence ◽  
Fruit Size ◽  
Punica Granatum ◽  
Fruit Trees ◽  
Fruit Weight ◽  
Shoot Length ◽  
Marketable Yield ◽  
Disease Attack ◽  
Punica Granatum L

Pruning of fruit trees is an important aspect for the improvement of fruit quality and to minimize the pests and disease attack. Pruning was performed in the month of December in seven year old unpruned trees of Punica granatum cv. Knadhdri Kabuli having many interfering branching and a heavy infestation of bacterial blight orchard. The pruning treatments viz., T1: Retention of 15cm fruiting shoot length, T2: Retention of 30cm fruiting shoot length, T3: Retention of 45cm fruiting shoot length, T4: Retention of 60cm fruiting shoot length and T5: control (No heading back and no thinning) plant. The results of the present investigation revealed that among different pruning treatment, the best results in terms of shoot extension (56.34 cm), fruit size (Diameter 9.66 cm and Length 9.65 cm, fruit weight (278.50 g), marketable yield (10.25 kg) and fruit qualities were in fruits from T1 and T2 where retention of 15cm fruiting shoot length respectively and retention of 30cm fruiting shoot length were maintained. However, maximum fruit set (54.73%) was recorded in control, and it decreased with increasing pruning intensity. The pruning treatments also proved beneficial in controlling bacterial blight on fruit (12.86%) and leaf surface (26.60%) to some extent.

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