Spore Production and Latent Period as Mechanisms of Resistance to Cercospora Arachidicola in Four Peanut Genotypes 1,3

1980 ◽  
Vol 7 (2) ◽  
pp. 88-90 ◽  
Author(s):  
D. J. Foster ◽  
M. K. Beute ◽  
J. C. Wynne
Keyword(s):  
Latent Period ◽  
Unit Area ◽  
Spore Production ◽  
Cercospora Arachidicola ◽  
Mechanisms Of Resistance ◽  
Lesion Area ◽  
Arachis Batizocoi

Abstract Arachis batizocoi, A. monticola and two genotypes of A. hypogaea (‘Florigiant’ and PI 109839) chosen to represent differing levels of resistance to early leafspot (Cercospora arachidicola) were evaluated for their effects on production of conidia per lesion, conidia per unit area of lesion and latent period necessary for sporulation. The largest lesions and the most conidia per lesion and unit lesion area were produced on cultivar ‘Florigiant’. PI 109839 had smaller lesions than Florigiant. Fewer conidia per lesion and per unit lesion area were produced on PI 109839 than Florigiant C. arachidicola sporulated abundantly on lesions from both Florigiant and PI 109839 15 days after inoculation. Size of lesions and conidia per lesion did not differ between A. monticola and PI 109839 but conidia per unit lesion area were fewer on A. monticola. The smallest lesions and the fewest conidia per lesion and per unit lesion area were produced on A. batizocoi. C. arachidicola did not begin sporulating on A. monticola and A. batizocoi until 18 days after inoculation. Sporulation of C. arachidicola was observed on defoliated leaves of A. monticola and A. batazocoi 21 days after inoculation.

Resistance to Late Leafspot Peanut of Progenies Selected for Resistance to Early Leafspot1

1985 ◽  
Vol 12 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Stephen B. Walls ◽  
J. C. Wynne ◽  
M. K. Beute
Keyword(s):  
Latent Period ◽  
Arachis Hypogaea ◽  
Field Data ◽  
Rank Correlation ◽  
Cercospora Arachidicola ◽  
Lesion Area ◽  
Components Of Resistance ◽  
Arachis Hypogaea L ◽  
Susceptible Control ◽  
Field Plots

Abstract Fifty-six F7 peanut (Arachis hypogaea L.) lines previously selected for resistance to early leafspot (Cercospora arachidicola Hori) were evaluated in the field and greenhouse for resistance to late leafspot [Cercosporidium personatum (Berk. & Curt.) Deighton]. After growing in field plots for 12 weeks, differences for numbers of lesions per 15 leaves were found among the lines and between these lines and NC 3033, the susceptible control. Eleven lines with the fewest numbers of lesions and their parents were screened in the greenhouse for components of resistance. These lines had lesions that were significantly smaller, produced lesions with longer latent periods, and produced fewer conidia than NC 3033. Latent periods ranged from 23 to 26 days for the selections compared to 20 days for NC 3033. GP-NC 343 and NC 5 were the most resistant parents with latent periods of 24 days each. A rank correlation of greenhouse and field data revealed that the rank of an entry in the greenhouse for latent period, lesion area and amount of sporulation was correlated with the rank of the entry in the field. Thus, these variables could be used as measurements of resistance to predict the performance of a line in the field for this population. Lines with resistance to late leafspot can be selected from a population of lines with this parentage which have been selected for resistance to early leafspot.

scholarly journals Adaptation of Biotrophic Leaf Pathogens to Fertilization-Mediated Changes in Plant Traits: A Comparison of the Optimization Principle to Invasion Fitness

2020 ◽  
Vol 110 (5) ◽  
pp. 1039-1048
Author(s):  
Pierre-Antoine Précigout ◽  
Corinne Robert ◽  
David Claessen
Keyword(s):  
Growth Rate ◽  
Latent Period ◽  
Exponential Growth ◽  
Plant Traits ◽  
Adaptive Dynamics ◽  
Spore Production ◽  
Exponential Growth Rate ◽  
Evolutionarily Stable Strategies ◽  
Invasion Fitness ◽  
Evolutionary Response

One of the conclusions of evolutionary ecology applied to agroecosystem management is that sustainable disease management strategies must be adaptive to overcome the immense adaptive potential of crop pathogens. In this context, knowledge of how pathogens adapt to changes in cultural practices is necessary. In this article we address the issue of the evolutionary response of biotrophic crop pathogens to changes in fertilization practices. For this purpose, we compare predictions of latent period evolution based on three empirical fitness measures (seasonal spore production, within-season exponential growth rate, and area under disease progress curves [AUDPCs]) with predictions based on the concept of invasion fitness from adaptive dynamics. We use pairwise invisibility plots to identify the evolutionarily stable strategies (ESSs) of the pathogen latent period. We find that the ESS latent period is in between the latent periods that maximize the seasonal spore production and the within-season exponential growth rate of the pathogen. The latent periods that maximize the AUDPC are similar to those of the ESS latent periods. The AUDPC may therefore be a critical variable to determine the issue of between-strain competition and shape pathogen evolution.

scholarly journals Seasonal Infection of the Weed Dyer's Woad by a Puccinia sp. Rust Used for Biocontrol, and Effects of Temperature on Basidiospore Production

Plant Disease ◽  
2000 ◽  
Vol 84 (7) ◽  
pp. 753-759 ◽  
Author(s):  
Karen M. Flint ◽  
Sherman V. Thomson
Keyword(s):  
Latent Period ◽  
Exposure Period ◽  
Spore Production ◽  
Symptom Expression ◽  
Optimum Temperature ◽  
Field Evidence ◽  
Effects Of Temperature ◽  
Seasonal Infection

Potted dyer's woad rosettes exposed to natural rust inoculum at field sites became infected when exposed from late April through early July, depending upon the location. The latent period between exposure and symptom expression varied from 9 to 54 weeks. The length of this latent period was unrelated to either the age of plants at exposure or the exposure period itself. The age of rosettes at the time of exposure did not affect the incidence of infection. Fall infection of potted rosettes occurred, but the incidence was low. When naturalized stands of woad were inoculated with teliosori, either fresh or dried, the incidence of infection was 58 to 76%, compared with 2 to 7% incidence in noninoculated plants. Basidiospores were readily produced from intact teliosori when suspended over water agar, with the highest rate of production between 3 and 6 h of incubation, at 10 to 20°C. The optimum temperature for basidiospore production over a 24-h period was 15°C, but they were produced at temperatures as low as 5°C, although not at 25°C. These lower-than-expected temperatures for spore production corroborate the field evidence that dyer's woad rust most actively infects in springtime, when temperatures are comparatively low and rainfall is more frequent.

scholarly journals Shared influence of pathogen and host genetics on a trade‐off between latent period and spore production capacity in the wheat pathogen, P uccinia triticina

2012 ◽  
Vol 6 (2) ◽  
pp. 303-312 ◽  
Author(s):  
Bénédicte Pariaud ◽  
Femke Berg ◽  
Frank Bosch ◽  
Stephen J. Powers ◽  
Oliver Kaltz ◽  
...  
Keyword(s):  
Latent Period ◽  
Production Capacity ◽  
Spore Production ◽  
Trade Off ◽  
Host Genetics

scholarly journals Effect of Lesion Age, Humidity, and Fungicide Application on Sporulation of Alternaria alternata, the Cause of Brown Spot of Tangerine

Plant Disease ◽  
2006 ◽  
Vol 90 (8) ◽  
pp. 1051-1054 ◽  
Author(s):  
R. F. Reis ◽  
A. de Goes ◽  
S. N. Mondal ◽  
T. Shilts ◽  
F. C. Brentu ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Unit Area ◽  
Spore Production ◽  
Brown Spot ◽  
Yield Losses ◽  
Conidial Production ◽  
Leaf Lesion ◽  
Inoculum Production ◽  
The World ◽  
Alternaria Brown Spot

Alternaria brown spot, caused by Alternaria alternata, causes yield losses and fruit blemishes on many tangerines and their hybrids in most citrus areas of the world where susceptible cultivars are grown. Although the conditions affecting infection and disease severity are known, little information is available on inoculum production on infected tissue. We found that sporulation on leaves began about 10 days after symptoms developed, was abundant from 20 to 40 days, and declined thereafter. Conidial production was far greater on leaf than on fruit or twig lesions. Spore production per unit area of leaf lesion was greater on the more susceptible hybrids, Minneola and Orlando tangelos, than on the less susceptible Murcott tangor. At 74% relative humidity, conidial production on leaf lesions was low, but it was abundant at 85, 92.5, 96, and 100%. Application of QoI or copper fungicides, but not ferbam, suppressed sporulation on leaf lesions for about 14 to 21 days after application. Additional applications did not appear to be more effective than a single spray in reducing inoculum production.

scholarly journals Sensitivity to Protectant Fungicides and Pathogenic Fitness of Clonal Lineages of Phytophthora infestans in the United States

1997 ◽  
Vol 87 (9) ◽  
pp. 973-978 ◽  
Author(s):  
Masayasu Kato ◽  
Eduardo S. Mizubuti ◽  
Stephen B. Goodwin ◽  
William E. Fry
Keyword(s):  
United States ◽  
Latent Period ◽  
Phytophthora Infestans ◽  
Potato Cultivar ◽  
The United States ◽  
Clonal Lineage ◽  
Fitness Components ◽  
Lesion Area ◽  
Simulation Experiments ◽  
The Us

Since 1991, dramatic changes have occurred in the genetic composition of populations of Phytophthora infestans in the United States. Clonal lineages recently introduced into the United States (US-7 and US-8) are more common now than the previously dominant lineage (US-1). To help determine why these changes occurred, four clonal lineages of P. in-festans common during the early 1990s in the United States and Canada were evaluated for sensitivity to the protectant fungicides mancozeb and chlorothalonil using amended agar assays for isolates collected from 1990 to 1994. No isolate or lineage was resistant to either mancozeb or chlorothalonil. There were significant differences among isolates for degree of sensitivity to one fungicide individually, but there were no significant (P = 0.05) differences among the US-1, US-6, US-7, and US-8 clonal lineages for degree of sensitivity to both fungicides. Therefore, resistance to protectant fungicides cannot explain the rapid increase in frequency of the US-7 and US-8 clonal lineages. Three components of pathogenic fitness (latent period, lesion area, and sporulation after 96 h) were tested for the three clonal lineages that were detected most commonly during 1994 (US-1, US-7, and US-8). All but one of the isolates in this analysis were collected during 1994 and evaluated within 10 months of collection by inoculating detached leaflets of the susceptible potato cultivar Norchip. There were significant differences between the US-1 and US-8 clonal lineages for lesion area and sporulation, and between US-1 and US-7 for latent period. The US-6 clonal lineage was excluded from the pathogenic fitness experiments, because no isolates of this lineage were collected during 1994. Compared with US-7 and US-8, US-1 had the longest latent period and the smallest lesions with the least sporulation. Incorporation of the differences between US-1 and US-8 in computer simulation experiments revealed that significantly more protectant fungicide (e.g., 25%) would be required to suppress epidemics caused by the US-8 clonal lineage compared with US-1. These differences in pathogenic fitness components probably contribute to the general predominance of the “new” clonal lineages (especially US-8) relative to the “old” US-1 lineage.

Variation in Aggressiveness and Virulence Among Isolates of Cercospora arachidicola

1999 ◽  
Vol 26 (2) ◽  
pp. 95-98
Author(s):  
J. C. Tuggle ◽  
O. D. Smith ◽  
J. L. Starr
Keyword(s):  
North Carolina ◽  
Latent Period ◽  
Incubation Period ◽  
Leaf Spot ◽  
Cercospora Arachidicola ◽  
Host Genotype ◽  
Breeding Lines ◽  
Lesion Diameter ◽  
Sporulation Rate ◽  
Greenhouse Tests

Abstract Forty-three isolates of Cercospora arachidicola, incitant of early leaf spot of peanut, were collected from peanut fields in Florida, Georgia, North Carolina, and Texas. Variation in aggressiveness among these isolates using the susceptible peanut cultivar Spanco was examined in greenhouse tests. Variation (P ≤ 0.05) among the isolates was observed for the parameters of incubation period (IP), the reciprocal of the latent period (an estimate of sporulation rate), and number of lesions per leaflet (LN). Additionally, as a group, the isolates from Texas were more aggressive in terms of having a shorter latent period and greater number of lesions per leaflet than isolates from other states. When a subset of eight isolates, which differed in aggressiveness based on IP and LN, were tested on Spanco and three early leaf spotresistant breeding lines (TX957910–5, TX957910–27, TX957910–68), the breeding lines were resistant to all isolates and, except for lesion diameter, no host genotype-by-isolate interaction was detected (P > 0.05). These observations suggest that success of efforts to identify resistance to early leaf spot can be affected by the aggressiveness of the pathogen isolate. Additionally, the resistance of the breeding lines tested is likely to be effective against a wide array of isolates of C. arachidicola.

Components of quantitative resistance to anthracnose (Colletotrichum gloeosporioides) in tetraploid accessions of the pasture legume Stylosanthes hamata

1993 ◽  
Vol 33 (7) ◽  
pp. 855 ◽  
Author(s):  
N Iamsupasit ◽  
S Chakraborty ◽  
DF Cameron ◽  
SW Adkins
Keyword(s):  
Latent Period ◽  
Incubation Period ◽  
Infection Type ◽  
Quantitative Resistance ◽  
Quantitative Relationship ◽  
Spore Production ◽  
Stylosanthes Hamata ◽  
Severity Scores ◽  
Similar Disease ◽  
Pasture Legume

Partial resistance to the anthracnose pathogen Colletotriclzum gloeosporioides was characterised in 6 tetraploid accessions and cv. Verano of the tropical pasture legume Stylosanthes hamata. Four components of resistance (incubation period, latent period, spore production, weighted infection type) were determined and compared with those of the susceptible S. scabra cv. Fitzroy. There were significant differences between the accessions for all resistance components. The mechanisms of resistance in the 3 most resistant accessions appeared to be different, with accession 55830 having a longer incubation period but higher sporulation per day than either 92715 or 92412. Spore production, weighted infection type, and latent period were significantly (P<0.05) correlated with resistance of adult plants in the field (ADPC). The weighted infection type was useful in discriminating between accessions that had similar disease severity scores. A quantitative relationship was established between 2 components, latent period and spore production per day, and the ADPC, using a multiple regression analysis (r2 = 0.9). If verified using a large number of accessions, such analysis may be used to obtain an index of resistance that may predict resistance levels in the field based on the components.

scholarly journals Components of Resistance to Late Leafspot in Peanut. II. Correlations Among Components and Their Significance in Breeding for Resistance1

1988 ◽  
Vol 15 (2) ◽  
pp. 76-81 ◽  
Author(s):  
Z. A. Chiteka ◽  
D. W. Gorbet ◽  
D. A. Knauft ◽  
F. M. Shokes ◽  
T. A. Kucharek
Keyword(s):  
Latent Period ◽  
Field Studies ◽  
Lesion Size ◽  
Spore Production ◽  
Necrotic Area ◽  
The Third ◽  
Lesion Diameter ◽  
Arachis Hypogaea L ◽  
Lesion Number ◽  
Highly Correlated

Abstract A total of 116 peanut (Arachis hypogaea L.) genotypes, which included all market types, were evaluated for resistance to late leafspot (Cercosporidium personatum Berk, and Curt. (Deighton)) in three tests during 1986. Two tests were conducted in greenhouses at Gainesville and Quincy, Florida. The third test was conducted in the field near Marianna, Florida. Lesion number per leaf, percent leaf necrotic area, lesion diameter, spore production, and latent period were evaluated. Correlations were calculated between greenhouse and field studies. Contributions of each component of resistance to an overall plant appearance score was also determined. Amount of sporulation, lesion size, and latent period were highly correlated with each other and with percent leaf necrotic area within tests. The rank of genotypes in the field was significantly correlated with the rank in the greenhouse for latent period (r = 0.57), lesion diameter (r = 0.46), and sporulation (r = 0.59). Sporulation, lesion size, and latent period were the most important components contributing to visual plant appearance score. Sporulation accounted for most of the variability in the score.

scholarly journals Crop Fertilization Impacts Epidemics and Optimal Latent Period of Biotrophic Fungal Pathogens

2017 ◽  
Vol 107 (10) ◽  
pp. 1256-1267 ◽  
Author(s):  
Pierre-Antoine Précigout ◽  
David Claessen ◽  
Corinne Robert
Keyword(s):  
Life History ◽  
Latent Period ◽  
Fungal Pathogens ◽  
Negative Relationship ◽  
Agricultural Practices ◽  
Life History Evolution ◽  
Critical Issue ◽  
Spore Production ◽  
Life History Trait ◽  
Fertilization Level

Crop pathogens are known to rapidly adapt to agricultural practices. Although cultivar resistance breakdown and resistance to pesticides have been broadly studied, little is known about the adaptation of crop pathogens to fertilization regimes and no epidemiological model has addressed that question. However, this is a critical issue for developing sustainable low-input agriculture. In this article, we use a model of life history evolution of biotrophic wheat fungal pathogens in order to understand how they could adapt to changes in fertilization practices. We focus on a single pathogen life history trait, the latent period, which directly determines the amount of resources allocated to growth and reproduction along with the speed of canopy colonization. We implemented three fertilization scenarios, corresponding to major effects of increased nitrogen fertilization on crops: (i) increase in nutrient concentration in leaves, (ii) increase of leaf lifespan, and (iii) increase of leaf number (tillering) and size that leads to a bigger canopy size. For every scenario, we used two different fitness measures to identify putative evolutionary responses of latent period to changes in fertilization level. We observed that annual spore production increases with fertilization, because it results in more resources available to the pathogens. Thus, diminishing the use of fertilizers could reduce biotrophic fungal epidemics. We found a positive relationship between the optimal latent period and fertilization when maximizing total spore production over an entire season. In contrast, we found a negative relationship between the optimal latent period and fertilization when maximizing the within-season exponential growth rate of the pathogen. These contrasting results were consistent over the three tested fertilization scenarios. They suggest that between-strain diversity in the latent period, as has been observed in the field, may be due to diversifying selection in different cultural environments.

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