scholarly journals Tan spot - the most harmful wheat leaf disease in Latvia

2012 ◽  
Vol 58 (1) ◽  
pp. 5-10
Author(s):  
Biruta Bankina
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Stem Elongation ◽  
Leaf Age ◽  
Tan Spot ◽  
Wheat Varieties ◽  
Wheat Diseases ◽  
Wheat Development ◽  
Ripening Rate ◽  
The Relationship

Tan spot (<i>Pyrenophora tritici</i>-<i>repentis</i>) is one of the most important wheat diseases in Latvia. Significant spreading of this disease was observed from 1998. Field experiments were carried out at the Research and Training Farm "Peterlauki" of the Latvia University of Agriculture, during 1998-2003. Development of diseases was observed on 14 winter wheat varieties, dynamics of development was investigated on 'Donskaja polukarlikovaja' and 'Stava'. Assessments of the disease severity were carried out on the upper three leaves each week from the start of stem elongation to full ripening. Tan spot was observed at the stage of stem elongation in 2003, and only after flowering in 1999. Increase of the disease severity was slow until stage of milk ripeness, and only in late stages of wheat development sharp increase of the disease was observed. Total rate of infection (through the session of vegetation) was very slow (0,01-0,19), but during ripening rate achieved 0,5-0,6. The main reason of so unequal development of the disease seems changes in amount of infection sources. Other possible reason of rapid increase of the disease development is the relationship between leaf age and susceptibility to the disease. Further research is necessary for better understanding of tan spot life cycle.

scholarly journals Ancient Wheat Species (Triticum sphaerococcum Perc. and T. persicum Vav.) in Organic Farming: Influence of Sowing Density on Agronomic Traits, Pests and Diseases Occurrence, and Weed Infestation

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 556
Author(s):  
Małgorzata Szczepanek ◽  
Grzegorz Lemańczyk ◽  
Robert Lamparski ◽  
Edward Wilczewski ◽  
Radomir Graczyk ◽  
...  
Keyword(s):  
Organic Farming ◽  
Field Experiments ◽  
Agronomic Traits ◽  
Stem Elongation ◽  
Tan Spot ◽  
Wheat Species ◽  
Pests And Diseases ◽  
Weed Infestation ◽  
Dwarf Wheat ◽  
The Impact

Crop management should be determined to reintroduce ancient wheat. This study aimed to determine: i. the response of the yield of ancient wheat on sowing density; ii. the impact of sowing density on plant health, weed infestation and pest occurrence. Field experiments were carried out in Poland, on three organic farms. The factors were: (1) wheat species: Persian wheat (Triticum persicum Vav.) and Indian dwarf wheat (T. sphaerococcum Perc.), (2) sowing density (400, 500, and 600 grains m−2). Increasing the sowing density of T. sphaerococcum from 400 to 600 grains m−2 increases the grain yield and reduces the pest pressure (Oulema spp. and Aphididae). Sowing densities did not affect the severity of powdery mildew at stem elongation as well as root rot and eyespot at the development of fruit. At the highest sowing density, the leaf area with tan spot symptoms was the highest. The eyespot symptoms occurred more frequently and the damaged plant surface caused by Oulema spp. was larger on T. sphaerococcum. Persian wheat turned out to be more susceptible to weed infestation. Indian dwarf wheat and Persian wheat are useful for organic farming, and the sowing density should be 500 or 600 grains m−2 and 400 grains m−2, respectively.

Yield losses in canola in response to blackleg disease

2020 ◽  
Vol 100 (5) ◽  
pp. 488-494
Author(s):  
Yixiao Wang ◽  
Stephen E. Strelkov ◽  
Sheau-Fang Hwang
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Leptosphaeria Maculans ◽  
Economic Benefits ◽  
Control Measures ◽  
Yield Losses ◽  
Blackleg Disease ◽  
Brassica Napus L ◽  
Moderately Resistant ◽  
The Relationship

Blackleg, caused by Leptosphaeria maculans (Desm.) Ces. & De Not., is an important disease of canola (Brassica napus L.) worldwide. In Canada, blackleg is managed mainly by the cultivation of resistant or moderately resistant canola hybrids. Field experiments were conducted in Edmonton, AB, Canada, in 2017 and 2018 to determine the relationship between blackleg disease severity and yield in the moderately resistant canola hybrids ‘73-15RR’ and ‘1950RR’. Blackleg severity was rated on a 0–5 scale, where 0 = no disease and 5 = plant death. Regression analysis showed that relationships between disease severity and pod number and seed yield were best explained by second-degree quadratic equations in all site-years for both cultivars. Percentage yield loss increased by 18%–99% and 26%–86% in plants of ‘73-15RR’ and ‘1950RR’, respectively, with disease severities of 2–5 compared with plants with severities of 0–1. An improved knowledge of the relationship between blackleg severity and yield losses is important for a more accurate evaluation of the agronomic efficacy and economic benefits of control measures.

Effects of temperature and leaf wetness duration on infection of pear leaves by Venturia pirina

2000 ◽  
Vol 51 (1) ◽  
pp. 97 ◽  
Author(s):  
O. N. Villalta ◽  
W. S. Washington ◽  
G. M. Rimmington ◽  
P. A. Taylor
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Leaf Wetness ◽  
Leaf Wetness Duration ◽  
Controlled Conditions ◽  
Pyrus Communis L ◽  
Venturia Pirina ◽  
Effects Of Temperature ◽  
Relationship Of ◽  
The Relationship

The effects of temperature and wetness duration on the infection of pear leaves (Pyrus communis L.) by Venturia pirina were studied by inoculating plants with ascospores and conidia under controlled conditions and in the field. Under controlled inoculations, minimum wetness durations that lead to leaf infections by ascospores were 27, 15, 13, 11, 10, 9, and 9 h at 4, 8, 10, 12, 15, 20, and 25°C, respectively. In parallel inoculations with conidia, the minimum wetness durations that lead to leaf infections were similar to ascospores at temperatures between 12°C and 25°C, but at lower temperatures (4, 8, 10°C), conidia infected leaves only after an additional 2 h of leaf wetness. The relationship between minimum wetness times and temperature was best described using an exponential regression. In field experiments, leaf infection on plants inoculated with ascospores and conidia under various naturally occurring wetness and temperature conditions was in close agreement with those under controlled conditions. Disease severity (percent of leaf area infected) increased with increasing leaf wetness duration at all temperatures. The optimum temperature for infection was 20°C. Analysis of variance with orthogonal polynomial contrasts was used to define the relationship of the angular transformation of disease severity to temperature and leaf wetness duration.

Relationships between stripe rust severity and grain yield loss at Dooen, Victoria

1988 ◽  
Vol 39 (4) ◽  
pp. 563 ◽  
Author(s):  
JS Brown
Keyword(s):  
Grain Yield ◽  
Disease Severity ◽  
Stripe Rust ◽  
Growth Stage ◽  
Field Experiments ◽  
Yield Loss ◽  
Rust Severity ◽  
Cent Disease ◽  
The Relationship ◽  
Best Estimator

The relationship between stripe rust severity and grain yield loss in wheat was studied in two field experiments. Wheat cultivars varying in response to the disease were used to produce epidemics of differing severity. Regression models were used to examine the relationship between disease severity and yield loss. The best estimator of yield loss was an estimate of disease severity at the end of anthesis-early berry growth stage. The relationship between per cent yield loss (YL) and per cent disease severity (DS) at that growth stage was established to be YL = 0.479DS + 0.84.

scholarly journals Tan spot development peculiarities in Latvia

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 381-383
Author(s):  
B. Bankina
Keyword(s):  
Field Experiments ◽  
Tan Spot ◽  
Severity Of Disease ◽  
Pyrenophora Tritici Repentis ◽  
Wheat Diseases ◽  
Flowering Rate ◽  
Severity Of The Disease ◽  
First Time ◽  
And Training ◽  
Very High

Tan spot, caused by Pyrenophora tritici-repentis (Died.) Drechs., anamorph Drechslera tritici-repentis is one of the most important wheat diseases in the world, especially in the regions of intensive wheat growing. Tan spot had established for the first time in Latvia in 1994. Epidemic of this disease was observed in Latvia in 1998. Development of tan spot were investigated in field experiments at the Research and Training Farm “Peterlauki” of Latvia University of Agriculture in 1998–2001. Level of incidence and severity of tan spot differed depending on varieties and years. Severity of the disease was 16–71% in 1999; 0.1–5% in 2000 and 4–18% in 2001 depending on varieties at the time of ripening. 1999 summer was extremely dry, and development of disease was not observed. Explosion of disease was observed at the second half of June in 2000 and 2001, without reference to varieties. Date of increasing start differed, but in all cases important development was observed after flowering. Rate of increasing of disease was very high, during two weeks severity of disease increased from 0.1 till maximum of severity. Amount and frequency of rainy differed in 2000 and 2001, but increase on disease was very similar, it means, we need more information about favourable conditions for Drechslera tritici-repentis. Sexual stage Pyrenophora tritici-repentis was observed in Latvia for the first time. Further investigations are necessary, because relationships between meteorological conditions and stages of development are unclear.

Biological Control of Kudzu (Pueraria lobata) with the Plant PathogenPseudomonas syringaepv.phaseolicola

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 645-649 ◽  
Author(s):  
Nina K. Zidack ◽  
Paul A. Backman
Keyword(s):  
Biological Control ◽  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Field Experiments ◽  
Leaf Age ◽  
Early Spring ◽  
Pueraria Lobata ◽  
In Planta ◽  
Young Leaves ◽  
Organosilicone Surfactant

Pseudomonas syringaepv.phaseolicolaformulated with an organosilicone surfactant was tested as a potential bioherbicide for kudzu. Greenhouse studies were performed to determine the effect of kudzu plant age and leaf age on disease severity and growth of the bacteriumin planta.Eight-week-old plants were more diseased 4 wk after spraying and had a higher potential for regrowth 7 wk after spraying than 12-wk-old plants. Young leaves developed water-soaked lesions earlier than older leaves and supported higher populations of bacteria. Data from field experiments at two separate locations indicated that single applications in late spring were as effective as multiple applications in early spring and were enhanced by repeat application. Three months after the beginning of the experiment, extensive regrowth occurred for all bioherbicide treatments and no differences were noted between treatments and the nontreated control.

scholarly journals Meta-Analysis in Plant Pathology: Synthesizing Research Results

2004 ◽  
Vol 94 (9) ◽  
pp. 1013-1017 ◽  
Author(s):  
M. S. Rosenberg ◽  
K. A. Garrett ◽  
Z. Su ◽  
R. L. Bowden
Keyword(s):  
Disease Severity ◽  
Statistical Power ◽  
Meta Analysis ◽  
Geographic Region ◽  
Test Results ◽  
Research Results ◽  
Wheat Diseases ◽  
Statistical Effect ◽  
The Difference ◽  
The Relationship

Meta-analysis is a set of statistical procedures for synthesizing research results from a number of different studies. An estimate of a statistical effect, such as the difference in disease severity for plants with or without a management treatment, is collected from each study along with a measure of the variance of the estimate of the effect. Combining results from different studies will generally result in increased statistical power so that it is easier to detect small effects. Combining results from different studies may also make it possible to compare the size of the effect as a function of other predictor variables such as geographic region or pathogen species. We present a review of the basic methodology for meta-analysis. We also present an example of meta-analysis of the relationship between disease severity and yield loss for foliar wheat diseases, based on data collected from a decade of fungicide and nematicide test results.

scholarly journals Number of Experiments Needed to Determine Wheat Disease Phenotypes for Four Wheat Diseases

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 103-108 ◽  
Author(s):  
William W. Bockus ◽  
Zhaohui Su ◽  
Karen A. Garrett ◽  
Bikram S. Gill ◽  
James P. Stack ◽  
...  
Keyword(s):  
Field Experiments ◽  
Tan Spot ◽  
Disease Phenotype ◽  
Head Blight ◽  
Septoria Leaf Blotch ◽  
Leaf Blotch ◽  
Disease Phenotypes ◽  
Wheat Diseases ◽  
Margin Of Error ◽  
Phenotype Data

Disease phenotypes for winter wheat cultivars were determined in numerous inoculated greenhouse and field experiments over many years. For four diseases, Fusarium head blight, tan spot, Septoria leaf blotch, and Stagonospora leaf blotch, at least 20 cultivars each had been evaluated in a minimum of five experiments. Reference cultivars of known disease reaction were included in each experiment, which allowed transformation of the percent disease severity data to a 1-to-9 scale for comparisons between experiments. Variations in scale values obtained for individual cultivars among the different experiments were used to calculate standard deviations for disease phenotype data. Standard deviations were used to calculate the number of experiment repetitions needed within each disease to achieve different levels of accuracy (margins of error). A margin of error of ±1.5 for the 1-to-9 scale was chosen as the best level of accuracy. Rounding values within this range would put the estimated disease phenotype within ±1 unit of the actual phenotype. To achieve a margin of error of ±1.5 for Fusarium head blight, tan spot, Septoria leaf blotch, and Stagonospora leaf blotch would require a mean that was calculated from a minimum of five, five, seven, and eight experiments, respectively. Personnel who report disease phenotype data to wheat producers or breeders should be aware of the number of experiments upon which they are basing their reports and adjust any disclaimers accordingly. Similarly, wheat breeders should be aware of the inherent variability in phenotyping these four wheat diseases and make appropriate adjustments to their selection protocols. With a minimum of five experimental repetitions, disease phenotype values obtained from inoculated greenhouse and field experiments had very high correlations (r = 0.81 to 0.92, P < 0.0001) with published Kansas State University Research and Extension ratings obtained from commercial fields.

Simulation on Extrusion Comminution Model of Roller Press

2010 ◽  
Vol 156-157 ◽  
pp. 1702-1707
Author(s):  
Xiang Wen Cheng ◽  
Jinchao Liu ◽  
Qi Zhi Ding ◽  
Li Ming Song ◽  
Zhan Lin Wang
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Field Experiments ◽  
Size Ratio ◽  
Optimum Operating ◽  
Extrusion Force ◽  
Particle Size Ratio ◽  
Small Constant ◽  
Working Parameters ◽  
The Relationship

How to predict the relationship among particle size and among product size, to establish the relationship between the granularity and working parameters in the process of grinding and to determine the optimum operating parameters. With proposing BS squeeze crush model by L. Bass and the idea of roll surface division as the material uneven extrusion force are adopted. Based on field experiments the experimental data is analyzed, the select function and the breakage functions are fitted with MATLAB software, and obtaining their model. The comminution model is determined by the roller division. We obtain the model parameter through the experimental data. Through model analysis shows: the relationship between particle breakage and energy absorption, namely the smaller size of the same power, the lower broken; the breakage diminishes with the decrease of particle size ratio and it will be tending to a small constant when the smaller particle size ratio. The breakage functions rapidly decrease within ratio of between 0.2-0.7. This shows: the energy consumption will rapidly increase when the particle size of less than 0.2 in broken; the selection diminish with the decrease of particle size. Pressure (8-9MPa) should be the most appropriate value.

scholarly journals Relationships Among the Feeding Behaviors of a Mirid Bug on Cotton Leaves of Different Ages and Plant Biochemical Substances

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Haiyan Song ◽  
Zhaoke Dong ◽  
Lili Li ◽  
Zengbin Lu ◽  
Chao Li ◽  
...  
Keyword(s):  
Negative Impact ◽  
Leaf Age ◽  
Leaf Traits ◽  
Cotton Leaf ◽  
Young Plant ◽  
Feeding Behaviors ◽  
Probing Behavior ◽  
Negative Effect ◽  
Mirid Bug ◽  
The Relationship

Abstract Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) tends to feed on young plant tissues. To explore the relationship between stylet probing behaviors of adult A. lucorum and conditions of cotton leaves, we conducted an experiment using electropenetrography (EPG). Behaviors were recorded on four cotton varieties, in relation to thickness and biochemical traits of differently-aged leaves. Cotton leaf age had a significant effect on the probing behavior of A. lucorum but cotton variety did not. One-day-old leaves of A. lucorum received the highest mean number of stylet probes (penetrations) per insect, and longest mean durations per insect of combined stylet probing or its components, cell rupture and ingestion behaviors. All of the leaf traits (thickness and biochemical substances) were similar among these four cotton varieties. Leaf thickness had a significantly negative effect on the same four variables above. Gossypol and tannin also had a negative impact on combined probing duration. Redundancy analysis showed that the four EPG variables were closely related to nutrient substances (amino acids, sugar, and water) while they had the opposite relationship with plant defense substances (gossypol and tannin). On cotton in the seedling stages, A. lucorum fed more readily on the youngest, thinnest leaves in our no-choice EPG experiments. Nutrients and chemical resistance substances determined the probing duration of A. lucorum. Our findings can contribute to better understanding of patterns of feeding and host consumption by A. lucorum, ultimately improving cotton resistance to A. lucorum.

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