Daily and seasonal spore dispersal by Mycosphaerella pinodes and development of mycosphaerella blight of field pea

2005 ◽  
Vol 83 (3) ◽  
pp. 302-310 ◽  
Author(s):  
Jin Xiu Zhang ◽  
W G Dilantha Fernando ◽  
Allen G Xue
Keyword(s):  
Disease Severity ◽  
Field Pea ◽  
Mycosphaerella Pinodes ◽  
Rain Event ◽  
Spore Dispersal ◽  
Rainfall Events ◽  
Inoculum Source ◽  
Practical Applications ◽  
Spore Release ◽  
Rain Events

Daily and seasonal spore dispersal of Mycosphaerella pinodes (Berk & Bloxam) Vestergren and the relationship of spore dispersal to distance and disease severity were investigated in a pea field in western Canada during two consecutive years. Most ascospores were released in response to rain events, during the first 23–27 d after the inoculum source area was infested with naturally diseased pea residue, whereas most pycnidiospores were trapped during the first 20 d. For both ascospores and pycnidiospores, the highest peaks of spore release occurred during the first 14–20 d after infestation. Few spores were trapped after day 27 after infestation. Daily peaks of ascospore and pycnidiospore release occurred between 1700 and 0400 hours. Most ascospores were released 1–2 d after a rain event and the largest peak appeared the first day after rain. In contrast, most pycnidiospores were released on the same day as rain occurred or the following day. The release of both spore types was associated with rainfall events ≥2 mm during the first 27 d after infestation but not with rainfall events after 27 d. Ascospore density was negatively correlated with distance from the inoculum source (r ≤ –0.92) and positively related to the disease severity (r ≥ 0.92). Disease severity decreased with increasing distance from the inoculum source. The patterns of spore dispersal associated with rain events have practical applications in the disease forecasting and spraying of chemicals to control the disease.Key words: field pea, mycosphaerella blight, rainfall, spore release.

The relationships among lodging, stem anatomy, degree of lignification, and resistance to mycosphaerella blight in field pea (Pisum sativum)

2005 ◽  
Vol 83 (8) ◽  
pp. 954-967 ◽  
Author(s):  
S Banniza ◽  
P Hashemi ◽  
T D Warkentin ◽  
A Vandenberg ◽  
A R Davis
Keyword(s):  
Pisum Sativum ◽  
Disease Severity ◽  
Field Experiments ◽  
Cellulose Fibre ◽  
Field Pea ◽  
Mycosphaerella Pinodes ◽  
Cellulose Content ◽  
Stem Anatomy ◽  
Lodging Resistance ◽  
Biochemical Basis

The relationships among lodging, stem anatomy, degree of stem lignification, and resistance to mycosphaerella blight (Mycosphaerella pinodes (Berk. & Blox.) Vestergr.) in field pea (Pisum sativum L.) were investigated in field experiments in Saskatchewan from 2000 to 2002. Disease severity, lodging resistance, plant height, internode length and diameter, and the cellulose, lignin, and fibre contents of stems were measured from 9 (2000) and 20 (2001, 2002) cultivars of field pea. Significant differences were observed in resistance to mycosphaerella blight and lodging among cultivars. In all years, ‘AC Tamor’ was among those cultivars with the highest disease ratings and lodging scores, whereas ‘CDC Striker’, ‘Carneval’, and ‘Integra’ were among those with the lowest ratings. Disease severity was positively correlated with lodging scores of plants. Lodging was negatively correlated with the proportions of supportive tissue (formerly parenchyma cells in the pith periphery, which have differentiated to sclerenchyma) and xylem in stem sections, whereas disease ratings were negatively correlated with xylem. Lignin and fibre contents in pea stems were negatively correlated with both lodging and mycosphaerella blight severity. Cellulose content was also negatively correlated with lodging scores. This study establishes an anatomical and biochemical basis for further research into pea stem lodging and disease resistance. Key words: cellulose, fibre, lignin, sclerenchyma, supportive tissue, xylem.

scholarly journals Evaluation of biological and agrichemical products for control of Neonectria ditissima conidia production

2017 ◽  
Vol 70 ◽  
pp. 87-96 ◽  
Author(s):  
M. Walter ◽  
R.E. Campbell ◽  
N.T. Amponsah ◽  
R.W.A. Scheper ◽  
R.C. Butler
Keyword(s):  
Bacillus Subtilis ◽  
Spore Production ◽  
Lesion Length ◽  
Rain Event ◽  
Physical Barrier ◽  
Glass Slides ◽  
Spore Release ◽  
Conidia Production ◽  
Artificial Rain ◽  
Rain Events

Inoculum control is critical in containing Neonectria ditissima but no agrichemical treatments are currently available to protect picking wounds during harvesting. Inhibition of conidia production was tested using a range of chemical-based pruning paints (PP) in a field trial in 2015. Mainly Bacillus subtilis-containing, biological products (BP) were tested at the same site in 2016. The BP were also tested in a detached-lesion experiment. Spore-producing field lesions were painted with the products and spore release monitored using glass slides after each rain event. For the detached-lesion study, spore production was monitored using rain traps after weekly artificial rain events. Reduced sporulation was observed in all experiments, but not for all treatments. Some PP created a physical barrier that sealed spores in, with lesions continuing to develop below the paint. No lesion healing was observed from any product in either year, with lesion length increasing for all treatments during the experiments.

Influence of agronomic traits on the expression of tissuespecific resistance to mycosphaerella blight in field pea

2007 ◽  
Vol 87 (1) ◽  
pp. 157-165 ◽  
Author(s):  
R. L. Conner ◽  
S. -F. Hwang ◽  
S. M. Woods ◽  
K. F. Chang ◽  
D. J. Bing ◽  
...  
Keyword(s):  
Pisum Sativum ◽  
Disease Severity ◽  
Agronomic Traits ◽  
Field Pea ◽  
Mycosphaerella Pinodes ◽  
Disease Development ◽  
Progress Curve ◽  
Late Maturity ◽  
Selection For ◽  
Crop Maturity

Mycosphaerella blight, caused by Mycosphaerella pinodes, is the most destructive disease of field pea (Pisum sativum L.) in western Canada. A 3-yr field study conducted at two field locations examined the effect of differences in lodging, growth stage and maturity on disease development among field pea cultivars that possess different forms of partial resistance. Significant differences in disease development, measured as area under the disease progress curve (AUDPC), and as disease severity on the leaves, stems and pods were observed among the field pea cultivars. These measurements of disease development were only influenced by differences in crop maturity in 2005. Only cultivars that were either intermediate or late maturing had low disease severity ratings or AUDPC values. Differences in the degree of lodging had a small inconsistent effect on the mycosphaerella blight ratings. These results suggest that differences in maturity should be considered in order to avoid inadvertent selection for late maturity while evaluating field pea lines or cultivars for mycosphaerella blight resistance. Key words: Mycosphaerella pinodes, field pea, Pisum sativum, maturity, lodging.

Response of field pea cultivars to chlorothalonil in the control of mycosphaerella blight

2003 ◽  
Vol 83 (2) ◽  
pp. 313-318 ◽  
Author(s):  
A. G. Xue ◽  
J. Charest ◽  
C. G. Davidson ◽  
D. W. McAndrew ◽  
D. J. Bing ◽  
...  
Keyword(s):  
Pisum Sativum ◽  
Key Words ◽  
Disease Severity ◽  
Seed Weight ◽  
Field Pea ◽  
Yield Potential ◽  
Mycosphaerella Pinodes ◽  
Seed Infection ◽  
Fungicide Treatment ◽  
Disease Pressure

The efficacy of chlorothalonil in controlling mycosphaerella blight in field pea was evaluated from 1998 to 2000 using 10 cultivars representing different leaf types, market classes, seed sizes, plant heights, and maturities. Significant differences ( P < 0.05) were observed among cultivars in disease severity, yield, 1000-seed weight (TSW), and seed infection each year. Cultivar × fungicide treatment interactions for these parameters were not significant in any of the 3 yr. Under both chlorothalonil treated and untreated conditions, Radley was the most resistant, while Carrera and Keoma were equally the most susceptible cultivars. A higher efficacy of chlorothalonil treatments was observed in 1999 when disease severity was greater than in 1998 or 2000. On average, chlorothalonil treatments reduced disease severity significantly in 1999 and 2000, but not in 1998. Overall, the fungicide increased yield by 6.4%, and TSW by 0.9–5.1%, which were significant in 1998 and 1999, but not in 2000. Based on 2-yr assessments of seed infection by Mycosphaerella pinodes, chlorothalonil reduced seed infection by 19.2%, which was significant in 1999, but not in 2000. Chlorothalonil treatments provide a greater benefit in years when disease pressure and yield potential are high. Key words: Field pea, Pisum sativum, mycosphaerella blight, Mycosphaerella pinodes, chlorothalonil

Assessment of tolerance for reducing yield losses in field pea caused by Aphanomyces root rot

2013 ◽  
Vol 93 (3) ◽  
pp. 473-482 ◽  
Author(s):  
R. L. Conner ◽  
K. F. Chang ◽  
S. F. Hwang ◽  
T. D. Warkentin ◽  
K. B. McRae
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Weight Ratio ◽  
Field Pea ◽  
Control Measures ◽  
Effective Control ◽  
Yield Losses ◽  
Plant Vigour ◽  
Shoot Weight ◽  
High Yields

Conner, R. L., Chang, K. F., Hwang, S. F., Warkentin, T. D. and McRae, K. B. 2013. Assessment of tolerance for reducing yield losses in field pea caused by Aphanomyces root rot. Can. J. Plant Sci. 93: 473–482. Aphanomyces root rot, caused by Aphanomyces euteiches Drechs., is a serious disease of peas (Pisum sativum) that can severely reduce seed yield, and few effective control measures are available. The development of pea cultivars with tolerance or partial resistance to Aphanomyces root rot is generally considered to be one of the best options to reduce yield loss. A 4-yr field study was conducted at disease-free sites and at an Aphanomyces root rot site to compare the responses of cultivars and lines in the presence and absence of Aphanomyces root rot, identify breeding lines with tolerance and to evaluate the effects of tolerance on plant growth, disease severity and yield. At the Aphanomyces root rot site, a second test was established in which the phosphite fungicide Phostrol™ was applied as a soil drench treatment to the pea cultivars and lines. Aphanomyces root rot reduced seedling emergence, biomass production and yield in the susceptible pea genotypes. However, line 00-2067 consistently produced relatively high yields at all the field sites. At the Aphanomyces root rot site, yield was closely associated with plant vigour and shoot weight. Small, but significant, differences (P<0.05) in disease severity were observed between susceptible cultivars and tolerant lines indicating that the lines producing high yields at the Aphanomyces root rot site are tolerant rather than partially resistant. The root/shoot weight ratio was very low in the tolerant lines, indicating that even though their root systems were reduced and severely damaged by root rot, they were still able to produce high yields under favourable conditions for the disease. Drench application of the fungicide Phostrol™ did not significantly reduce root rot severity or improve the performance of any of the pea cultivars or lines.

Using time compression approximation to determine actual infiltration rate from variable rainfall events

2017 ◽  
Vol 50 (1) ◽  
pp. 155-165 ◽  
Author(s):  
Yanyan Cheng ◽  
Guotao Cui ◽  
Jianting Zhu
Keyword(s):  
Infiltration Rate ◽  
Maximum Error ◽  
Richards Equation ◽  
Rainfall Time Series ◽  
Rainfall Events ◽  
Practical Applications ◽  
Time Compression ◽  
Cumulative Infiltration ◽  
Rainfall Patterns ◽  
Numerical Solver

Abstract Understanding infiltration into soils from rainfall events is important for many practical applications. The idea of time compression approximation (TCA) was proposed to simulate infiltration rate, which only requires the relationship between the potential infiltration rate (PIR) and potential cumulative infiltration (PCI). The TCA-based method can be used in any rainfall–runoff models since the PIR vs. PCI relationship can be developed independent of actual rainfall patterns. The main objective of this study is to establish guidelines on when this method can be adequately applied. The results based on the TCA are compared with those from the field observations and the Richards equation numerical solver for observed rainfall events and randomly generated rainfall patterns with prescribed temporal variabilities and hiatuses. For continuous rainfall with potential ponding, the maximum error of infiltration amount using the TCA-based method is less than 5%. The TCA-based method, in general, underestimates the total infiltration amount from variable rainfall events. Variance in rainfall time series does not significantly affect the errors of using the TCA-based method to determine the actual infiltration rate. The TCA-based method can produce reasonable results in simulating the actual infiltration rate for rainfall events with a short hiatus.

scholarly journals Continuous Monitoring of Turbidity and Conductivity in Wastewater Networks

2015 ◽  
Vol 28 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Thomas Bersinger ◽  
Isabelle Le Hécho ◽  
Gilles Bareille ◽  
Thierry Pigot ◽  
Alexandre Lecomte
Keyword(s):  
Total Nitrogen ◽  
Continuous Monitoring ◽  
Oxygen Demand ◽  
Rain Event ◽  
Aquatic Life ◽  
Pollutant Concentrations ◽  
Rain Events ◽  
The One ◽  
Continuous Estimation ◽  
The Impact

Continuous monitoring of the sanitation network of the urban catchment of Pau (southwest France) has been performed since March 2012 using rain gauges, flowmeters, as well as turbidity and conductivity probes. Good correlations were obtained between turbidity, total suspended solids (TSS) and chemical oxygen demand (COD) on the one hand, and conductivity and total nitrogen on the other hand. This allowed an instantaneous and continuous estimation of pollutant concentrations and fluxes since that date. In the present paper we focused on the results of October 2012, which was characterized by alternating periods of dry and rainy events. Turbidity and conductivity raw data show different trends during the study period depending on the parameter and the rain events. A turbidity peak is observed at the beginning of each rain event but its amplitude varies with the intensity of the rain and the length of the preceding dry weather period. Conversely, conductivity decrease during each rain event implying, that rain water acts as a dilution factor. The behaviour of COD and total nitrogen differ markedly due to their partitioning between the dissolved (total nitrogen) and particulate phases (COD). Daily pollutant fluxes allow a global comprehension and monitoring of the sewer system. Important COD fluxes during a rain event preceded by a long dry weather period highlight the importance of erosion of sedimentary deposits in the sewerage network. During these events, important fluxes are discharged into receiving water leading to the question of the impact on aquatic life. Generally, these results highlight the potential of online monitoring to better understand the behaviour of the sewer network on long or short time scales. This could be a useful tool to manage wastewater treatment.

scholarly journals Spatial structures and directionalities in Monsoonal precipitation over South Asia

2010 ◽  
Vol 17 (5) ◽  
pp. 371-381 ◽  
Author(s):  
N. Malik ◽  
N. Marwan ◽  
J. Kurths
Keyword(s):  
Indian Subcontinent ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Rain ◽  
Data Sets ◽  
Spatial Structures ◽  
Break Phase ◽  
Rainfall Events ◽  
Monsoonal Precipitation ◽  
Rain Events

Abstract. Precipitation during the monsoon season over the Indian subcontinent occurs in form of enormously complex spatiotemporal patterns due to the underlying dynamics of atmospheric circulation and varying topography. Employing methods from nonlinear time series analysis, we study spatial structures of the rainfall field during the summer monsoon and identify principle regions where the dynamics of monsoonal rainfall is more coherent or homogenous. Moreover, we estimate the time delay patterns of rain events. Here we present an analysis of two separate high resolution gridded data sets of daily rainfall covering the Indian subcontinent. Using the method of event synchronization (ES), we estimate regions where heavy rain events during monsoon happen in some lag synchronised form. Further using the delay behaviour of rainfall events, we estimate the directionalities related to the progress of such type of rainfall events. The Active (break) phase of a monsoon is characterised by an increase(decrease) of rainfall over certain regions of the Indian subcontinent. We show that our method is able to identify regions of such coherent rainfall activity.

Field assessment of partial resistance to mycosphaerella blight in Pisum subspecies accessions

2012 ◽  
Vol 92 (2) ◽  
pp. 289-296 ◽  
Author(s):  
R. L. Conner ◽  
B. D. Gossen ◽  
S. F. Hwang ◽  
K. F. Chang ◽  
K. B. McRae ◽  
...  
Keyword(s):  
Partial Resistance ◽  
Field Trials ◽  
Field Pea ◽  
Mycosphaerella Pinodes ◽  
Detached Leaf ◽  
High Severity ◽  
Field Assessment ◽  
Ascochyta Pinodes ◽  
The Mean ◽  
Production Areas

Conner, R. L., Gossen, B. D., Hwang, S. F., Chang, K. F., McRae, K. B. and Penner, W. C. 2012. Field assessment of partial resistance to mycosphaerella blight in Pisum subspecies accessions. Can. J. Plant Sci. 92: 289–296. Mycosphaerella blight, caused by Mycosphaerella pinodes (Berk. & Bloxam) Vestergr., the teleomorph of Ascochyta pinodes Jones, is an important foliar disease of field pea in the major production areas of the world. Partial resistance to mycosphaerella blight has been reported in some field pea cultivars, but, at best, they are only moderately susceptible. A 3-yr field study was conducted to evaluate the mycosphaerella blight reactions of 28 accessions from a number of subspecies of Pisum sativum L. and one accession of P. fulvum Sibth. A few of the accessions carried mutations for the genes af, tl, and st that affect the morphology of the leaflets, stipules and tendrils. Reactions to mycosphaerella blight were characterized based on the mean of the severity ratings taken on the two final assessment dates before the crop matured and also on the change in mycosphaerella blight severity between these two dates. In many of the accessions, severity ratings were similar to that of the moderately susceptible check cultivar, CDC Peko, while a few had high severity ratings similar to those of the susceptible check cultivars. The accession PI 512079, which has small stipules, branched petioles with many leaflets but no tendrils, had the lowest ratings for mycosphaerella blight severity. Four other accessions exhibited the smallest change in mycosphaerella blight severity at the end of the growing season. Differences in leaf morphology likely influenced the change in disease severity, since all the semi-leafless and leafless accessions had smaller changes in mycosphaerella blight severity than the susceptible check cultivars. In a detached leaf assay with two isolates of Mycosphaerella pinodes (Berk. & Bloxam) Vestergr., the smallest lesions formed on PI 512079, but otherwise the results failed to show a relationship with the observed severity values in the field trials.

scholarly journals Scale invariant events and dry spells for medium-resolution local rain data

2014 ◽  
Vol 21 (2) ◽  
pp. 555-567 ◽  
Author(s):  
A. Deluca ◽  
Á. Corral
Keyword(s):  
Finite Size ◽  
Mediterranean Coast ◽  
Rain Event ◽  
Scale Invariant ◽  
Scaling Properties ◽  
Medium Resolution ◽  
Dry Spells ◽  
Dry Spell ◽  
Rain Events ◽  
Rain Data

Abstract. We analyze distributions of rain-event sizes, rain-event durations, and dry-spell durations for data obtained from a network of 20 rain gauges scattered in a region of the northwestern Mediterranean coast. While power-law distributions model the dry-spell durations with a common exponent 1.50 ± 0.05, density analysis is inconclusive for event sizes and event durations, due to finite size effects. However, we present alternative evidence of the existence of scale invariance in these distributions by means of different data collapses of the distributions. These results demonstrate that scaling properties of rain events and dry spells can also be observed for medium-resolution rain data.

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