Components of Resistance to Late Leafspot in Peanut. I. Levels and Variability - Implications for Selection1

1988 ◽  
Vol 15 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Z. A. Chiteka ◽  
D. W. Gorbet ◽  
F. M. Shokes ◽  
T. A. Kucharek ◽  
D. A. Knauft
Keyword(s):  
Latent Period ◽  
Incubation Period ◽  
Lesion Size ◽  
Necrotic Area ◽  
Cercosporidium Personatum ◽  
Components Of Resistance ◽  
Lesion Diameter ◽  
Lesion Number ◽  
Resistant Genotypes

Abstract Components of resistance to late leafspot (Cercosporidium personatum (Berk. & Curt.) Deighton) in peanut were evaluated for 116 genotypes in three tests during 1986. The tests were conducted in greenhouses at Gainesville and Quincy, Florida and in the field near Marianna, Florida. The components of resistance evaluated were spore incubation period, latent period, lesion number per leaf, percent leaf necrotic area, lesion size, and amount of sporulation. Significant differences were observed in at least one test for each component. The greatest variability among genotypes was observed for lesion diameter and latent period. Resistant genotypes had smaller lesions, longer latent periods, and reducded sporulation. Among the most resistant genotypes were UF81206-1, UF81206-2. 72×32B-3-2-2-2-2-l-b3-B, and US 29-b3-B (85701).

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 Components of Resistance to Colletotrichum acutatum in Strawberry (Fragaria ×ananassa Duch.)

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 605E-605
Author(s):  
Gustavo Gimenez ◽  
James R. Ballington ◽  
Robert D. Milholland
Keyword(s):  
Latent Period ◽  
Incubation Period ◽  
Colletotrichum Acutatum ◽  
Disease Development ◽  
Infection Frequency ◽  
Fragaria Ananassa ◽  
Components Of Resistance ◽  
Significant Difference ◽  
Lesion Number ◽  
High Level

Two experiments were designed to study components of resistance to Colletotrichum acutatum on runners of three strawberry cultivars: incubation period, latent period, length of the lesion and spore production, and infection frequency with three levels of inoculum density (104, 105, 106 spores/cc) were considered. Rate of disease development was also determined. There were significant differences in all the components among the resistant and susceptible cultivars. Both 'Chandler' and 'Sweet Charlie' expressed susceptible reactions. The length of the lesion, number of spores/cm of the lesion, incubation period, latent period, and rate of anthracnose development were statistically similar in 'Chandler' and 'Sweet Charlie'. The only significant difference among them was found in infection frequency. 'Chandler' had a greater number of infection sites with all three concentrations of spores included. The cultivar Pelican showed a high level of partial resistance associated with longer incubation and latent periods, lower number of spores/cm of lesion, shorter lesion, smaller number of infection sites, and lower rate of disease development.

scholarly journals Heritability and Components of Resistance to Cercospora zeae-maydis Derived from Maize Inbred VO613Y

2006 ◽  
Vol 96 (6) ◽  
pp. 593-598 ◽  
Author(s):  
Stuart G. Gordon ◽  
Patrick E. Lipps ◽  
Richard C. Pratt
Keyword(s):  
Incubation Period ◽  
Gray Leaf Spot ◽  
Lesion Length ◽  
Host Genotype ◽  
Components Of Resistance ◽  
Cercospora Zeae Maydis ◽  
Lesion Number ◽  
Heritability Estimates ◽  
High Level ◽  
Resistant Genotypes

Gray leaf spot (GLS), caused by the fungus Cercospora zeae-maydis, is one of the most important foliar diseases of maize. This study was undertaken to estimate heritability of C. zeae-maydis resistance and examine the relationship between previously identified resistance loci and certain components of resistance including incubation period, lesion number, and maximum lesion length. Partially inbred progenies arising from hybridization between maize inbred lines VO613Y (high level of partial resistance) and Pa405 (susceptible) were examined in Ohio and South Africa. Heritability estimates of resistance were calculated based on severity and incubation period values. The range of heritability estimates based on severity was broad, with values ranging from approximately 0.46 to 0.81 (mean = 0.59). Estimates of mean heritability for incubation period were lowest (0.18), indicating that this component would likely be unsuitable for selection of germ plasm intended for deployment in diverse regions. Length of GLS lesions was significantly affected by host genotype, with resistant genotypes having shorter lesions from one site in Ohio during two seasons. Genotype also had a significant effect on incubation period and lesion number; the lower values for these components also were associated with resistant genotypes. The combined action of these resistance components resulted in lower overall disease severity.

scholarly journals The Influence of Silicon on Components of Resistance to Blast in Susceptible, Partially Resistant, and Resistant Cultivars of Rice

2001 ◽  
Vol 91 (1) ◽  
pp. 63-69 ◽  
Author(s):  
K. W. Seebold ◽  
T. A. Kucharek ◽  
L. E. Datnoff ◽  
F. J. Correa-Victoria ◽  
M. A. Marchetti
Keyword(s):  
Leaf Area ◽  
Incubation Period ◽  
Calcium Silicate ◽  
Magnaporthe Grisea ◽  
Upland Rice ◽  
Lesion Size ◽  
Diseased Leaf ◽  
Infection Efficiency ◽  
Components Of Resistance ◽  
Diseased Leaf Area

The application of silicon (Si) fertilizers reduces the severity of blast, caused by Magnaporthe grisea, in irrigated and upland rice; however, little research has been conducted to examine the epidemiological and etiological components of this reduction. Four cultivars of rice with differential susceptibilities to race IB-49 of M. grisea were fertilized with three rates of a calcium silicate fertilizer and inoculated with the pathogen to test the effects of Si on the following components of resistance to blast: incubation period, latent period, infection efficiency, lesion size, rate of lesion expansion, sporulation per lesion, and diseased leaf area. For each cultivar, the incubation period was lengthened by increased rates of Si, and the numbers of sporulating lesions, lesion size, rate of lesion expansion, diseased leaf area, and number of spores per lesion were reduced. Lesion size and sporulation per lesion were lowered by 30 to 45%, and the number of sporulating lesions per leaf and diseased leaf area were significantly reduced at the highest rate of Si. The net effect of Si on these components of resistance is an overall reduction in the production of conidia on plants infected with M. grisea, thereby slowing the epidemic rate of blast.

scholarly journals FIELD STUDIES TO QUANTIFY POLYGENIC RESISTANCE IN SPINACH TO WHITE RUST AND DOWNY MILDEW.

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1122G-1123
Author(s):  
L.P. Brandenberger ◽  
T.E. Morelock ◽  
J.C. Correll
Keyword(s):  
Latent Period ◽  
Downy Mildew ◽  
Field Studies ◽  
Lesion Size ◽  
Field Observations ◽  
Breeding Line ◽  
Spore Concentration ◽  
Polygenic Resistance ◽  
White Rust ◽  
Lesion Number

Field observations indicate that polygenic resistance to downy mildew (Peronospora farinosa f. sp. spinaciae) was observed during the course of a breeding program to develop polygenic resistance to white rust (Albugo occidentalis). Field studies were initiated using five cultivars and one breeding line to quantify the level of resistance to downy mildew and white rust. Separate plots were inoculated with each pathogen at a specific spore concentration and then subjected to a minimum dew period of 12h. Infection was quantified by measuring latent period, lesion number, lesion size, sporulation and percent leaf area infected.

scholarly journals FIELD STUDIES TO QUANTIFY POLYGENIC RESISTANCE IN SPINACH TO WHITE RUST AND DOWNY MILDEW.

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1122g-1123
Author(s):  
L.P. Brandenberger ◽  
T.E. Morelock ◽  
J.C. Correll
Keyword(s):  
Latent Period ◽  
Downy Mildew ◽  
Field Studies ◽  
Lesion Size ◽  
Field Observations ◽  
Breeding Line ◽  
Spore Concentration ◽  
Polygenic Resistance ◽  
White Rust ◽  
Lesion Number

Field observations indicate that polygenic resistance to downy mildew (Peronospora farinosa f. sp. spinaciae) was observed during the course of a breeding program to develop polygenic resistance to white rust (Albugo occidentalis). Field studies were initiated using five cultivars and one breeding line to quantify the level of resistance to downy mildew and white rust. Separate plots were inoculated with each pathogen at a specific spore concentration and then subjected to a minimum dew period of 12h. Infection was quantified by measuring latent period, lesion number, lesion size, sporulation and percent leaf area infected.

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.

scholarly journals Development parameters of the latent period as a response of rubber tree resistance to South American leaf blight

2021 ◽  
Vol 47 (2) ◽  
pp. 103-109
Author(s):  
João Alberto Zago Bevenuto ◽  
José Raimundo de Souza Passos ◽  
Edson Luiz Furtado
Keyword(s):  
Latent Period ◽  
Rubber Tree ◽  
Leaf Blight ◽  
Slight Variation ◽  
South American ◽  
Infection Frequency ◽  
Breeding Programs ◽  
Lesion Diameter ◽  
Complete Resistance ◽  
Traditional Breeding

ABSTRACT The major phytosanitary problem for rubber tree cultivation in Brazil is the disease known as South American leaf blight, caused by the fungus Microcyclus ulei. Its symptoms manifest in young leaves and cause intense defoliation, resulting in reduced latex production and even the death of susceptible plants. Thus, this disease consists in a constant threat to East Asian plantations. As worldwide traditional breeding programs have evolved, interspecific hybrid clones have currently been used for planting. They are more productive and show better resistance to pathogens. However, traditional breeding programs have not led to significant progress in resistance to South American leaf blight since the selection is directed to clones with complete resistance. In this pathosystem, horizontal or partial resistance (HR) and vertical or complete resistance (VR) can act simultaneously, evidencing their complexity and difficult quantification. This study aimed to: characterize the foliar lesion type in Hevea sp. X M. ulei pathosystem; verify the clonal susceptibility to pathogens; analyze the infection frequency for resistance quantification in Hevea sp. x M. ulei pathosystem, and recommend differentiating rubber tree clones to quantify M. ulei races in Brazil. The monocyclic parameters (latent period and lesion diameter) are applicable for resistance quantification in Hevea sp. x M. ulei pathosystem. Latent period had slight variation among clones. Lesion diameter had wide variation among clones and was a discriminating parameter for horizontal resistance and vertical resistance.

Factors Associated with Resistance to Puccinia arachidis

1982 ◽  
Vol 9 (2) ◽  
pp. 96-97 ◽  
Author(s):  
S. S. Sokhi ◽  
J. S. Jhooty
Keyword(s):  
Latent Period ◽  
Incubation Period ◽  
Infection Frequency ◽  
Rust Infection ◽  
Factors Associated ◽  
Puccinia Arachidis ◽  
Lower Infection

Abstract Peanut rust infection frequency, uredial size, incubation period and latent period was studied on 47 genotypes. Seventeen genotypes namely NCAC 17133-RF, PI,259747, PI,393643, PI,381622, PI,390593, PI,390595, PI,393517, PI,405132, J-11, Jh-352, 39–2, J1–24, 2704, US-74 and MK-374 showed a lower infection frequency and smaller uredosori, longer incubation and latent periods.

scholarly journals Resistance to Rust and Late Leafspot Diseases in Some Genotypes of Arachis hypogaea1

1982 ◽  
Vol 9 (1) ◽  
pp. 6-10 ◽  
Author(s):  
P. Subrahmanyam ◽  
D. McDonald ◽  
R. W. Gibbons ◽  
S. N. Nigam ◽  
D. J. Nevill
Keyword(s):  
Disease Resistance ◽  
Breeding Program ◽  
Field Conditions ◽  
Cercosporidium Personatum ◽  
Puccinia Arachidis ◽  
Lesion Diameter ◽  
Multiple Disease Resistance

Abstract Resistance to rust (Puccinia arachidis Speg.) and late leafspot (Cercosporidium personatum (Berk. & Curt.) Deighton) in some peanut genotypes was studied under field conditions. Late leafspot development was also assessed in the glasshouse and the parameters lesion diameter, defoliation percentage and sporulation gave highly significant correlations with the field disease scores. Several genotypes were found to be resistant to both rust and late leafspot and should be useful sources of multiple disease-resistance in a breeding program.

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