Taxonomy of the Pecan Scab Fungus Cladosporium caryigenum

Mycologia ◽  
1982 ◽  
Vol 74 (3) ◽  
pp. 382 ◽  
Author(s):  
T. R. Gottwald
Keyword(s):  
Pecan Scab ◽  
Cladosporium Caryigenum

scholarly journals Sensitivity of Cladosporium caryigenum to Propiconazole and Fenbuconazole

Plant Disease ◽  
1997 ◽  
Vol 81 (2) ◽  
pp. 163-166 ◽  
Author(s):  
Katherine L. Reynolds ◽  
Timothy B. Brenneman ◽  
Paul F. Bertrand
Keyword(s):  
Previous History ◽  
Cross Resistance ◽  
Relative Growth ◽  
Colony Diameter ◽  
Pecan Scab ◽  
History Of ◽  
Dmi Fungicides ◽  
Cladosporium Caryigenum ◽  
Positive Correlations ◽  
Two Populations

Monoconidial isolates of the pecan scab fungus, Cladosporium caryigenum, were obtained in 1993 and 1994 from one pecan orchard each in Jeff Davis and Troup counties in Georgia, counties with no previous history of exposure to demethylation-inhibiting (DMI) fungicides. Isolates were grown on potato dextrose agar (PDA) amended with propiconazole or fenbuconazole at 0,0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0, or 5.0 µg ml-1. After 4 to 5 weeks at 25°C, the diameter of each colony was measured. Relative growth was expressed as the colony diameter for each fungicide concentration as a percentage of the diameter on unamended PDA. (ED)50 values for both fungicides in all years and locations were lognormally distributed. Mean (ED)50 values ranged from 0.19 to 0.30 µg ml-1 for fenbuconazole and 0.12 to 0.17 µg ml-1 for propiconazole. There were highly significant positive correlations between sensitivity to propiconazole and sensitivity to fenbuconazole at all locations and years, indicating significant potential for development of cross-resistance to these compounds. A discriminatory concentration of 0.2 µg ml-1 propiconazole was selected for further monitoring of DMI sensitivity. With this discriminatory concentration, a sample size of 50 isolates was estimated to be sufficient to detect a difference of 8.3% in mean relative growth between two populations.

scholarly journals A Detached Leaf Technique for Studying Race-specific Resistance to Cladosporium caryigenum in Pecan

2002 ◽  
Vol 127 (5) ◽  
pp. 781-785 ◽  
Author(s):  
Patrick J. Conner
Keyword(s):  
High Frequency ◽  
Specific Resistance ◽  
Fungal Growth ◽  
Carya Illinoinensis ◽  
Detached Leaf ◽  
Pecan Scab ◽  
Detached Leaves ◽  
Cladosporium Caryigenum ◽  
Cape Fear ◽  
High Degree

A detached leaf screening technique was developed for studying specific interactions between pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars and isolates of the pecan scab fungus, Cladosporium caryigenum. Monoconidial isolates were obtained from leaf scab lesions on `Wichita', `Desirable', `Cape Fear', and `Elliot'. Each isolate was then inoculated onto detached leaves of each of the four cultivars and fungal growth was observed under the microscope after eight days. `Wichita', `Desirable', and `Cape Fear' isolates produced subcuticular hyphae at a much higher frequency when inoculated back onto the cultivar from which they were isolated in comparison to the other cultivars. The `Elliot' isolate was able to produce a high frequency of subcuticular hyphae when inoculated onto `Elliot' and `Cape Fear', but not when inoculated onto `Desirable' and `Wichita'. Field inoculations conducted with the `Wichita' and `Desirable' isolates validated the detached leaf protocol. The results obtained indicate that pecan scab is composed of multiple races with a high degree of specificity for host cultivars. A rapid whole-leaf staining system is presented which appears to have wide applicability to assessing fungal growth in leaves.

scholarly journals Microrganismos associados a frutos de diferentes cultivares de noz Pecan

2008 ◽  
Vol 32 (2) ◽  
pp. 659-662 ◽  
Author(s):  
Nádia Izumi Terabe ◽  
Cristiane Moreno Martins ◽  
Martin Homechin
Keyword(s):  
Penicillium Sp ◽  
Fusarium Sp ◽  
Cladosporium Caryigenum ◽  
Aspergillus Sp

O conhecimento do comportamento natural da nogueira Pecan às principais doenças é de suma importância para o estabelecimento do planejamento da implantação da cultura. O controle fitossanitário e tratos culturais devem ser realizados de modo a não comprometerem a qualidade do produto final, as amêndoas. Foram avaliadas nozes produzidas na safra de 2005 e oriundas de Uraí-PR, pelas cultivares Burkett, Frotscher e Moneymaker, para identificar e quantificar os microrganismos associados à amêndoas e cascas dos frutos, bem como observar diferenças entre organismos colonizadores das cultivares. Os frutos foram avaliados na pós-colheita, aos trinta dias de armazenamento em ambiente, através da metodologia do papel de filtro, sendo submetidos ou não à assepsia superficial. O fungo Cladosporium caryigenum, promotor da rancificação das amêndoas foi observado, em amêndoas e cascas, nas cultivares Burkett, Frotscher e Moneymaker; Fusarium sp., foi encontrado em porcentuais elevados, tanto em amêndoas quanto em cascas das três cultivares estudadas; Cephalothecium roseum, causador do mofo róseo em amêndoas, na cultivar Frotscher. Aspergillus sp. e Penicillium sp., causadores de emboloramento e produtores de aflotoxinas foram observados em porcentuais representativos, em amêndoas da cultivar Frotscher e em amêndoas e cascas das cultivares Frotscher, Burkett e Moneymaker, respectivamente. Os maiores porcentuais de perda do rendimento foram observados na cultivar Burkett, por causa da incidência de Colletotrichum sp., causador da antracnose em amêndoas, que acarreta escurecimento e deterioração do produto final, levando-o ao descarte.

A rapid method to monitor fungicide sensitivity in the pecan scab pathogen, Fusicladium effusum

2010 ◽  
Vol 29 (11) ◽  
pp. 1257-1263 ◽  
Author(s):  
Murat Seyran ◽  
Timothy B. Brenneman ◽  
Katherine L. Stevenson
Keyword(s):  
Rapid Method ◽  
Fungicide Sensitivity ◽  
Pecan Scab

scholarly journals Evidence for Sexual Reproduction: Identification, Frequency, and Spatial Distribution of Venturia effusa (Pecan Scab) Mating Type Idiomorphs

2018 ◽  
Vol 108 (7) ◽  
pp. 837-846 ◽  
Author(s):  
Carolyn A. Young ◽  
Clive H. Bock ◽  
Nikki D. Charlton ◽  
Chakradhar Mattupalli ◽  
Nick Krom ◽  
...  
Keyword(s):  
United States ◽  
Mating Type ◽  
Spatial Scales ◽  
Southeastern United States ◽  
Draft Genome ◽  
Apple Scab ◽  
Hypothetical Protein ◽  
Sexual Stage ◽  
Pecan Scab ◽  
Conserved Genes

Venturia effusa (syn. Fusicladium effusum), causal agent of pecan scab, is the most prevalent pathogen of pecan (Carya illinoinensis), causing severe yield losses in the southeastern United States. V. effusa is currently known only by its asexual (conidial) stage. However, the degree and distribution of genetic diversity observed within and among populations of V. effusa are typical of a sexually reproducing fungal pathogen, and comparable with other dothideomycetes with a known sexual stage, including the closely related apple scab pathogen, V. inaequalis. Using the mating type (MAT) idiomorphs from V. inaequalis, we identified a single MAT gene, MAT1-1-1, in a draft genome of V. effusa. The MAT1-1-1 locus is flanked by two conserved genes encoding a DNA lyase (APN2) and a hypothetical protein. The MAT locus spanning the flanking genes was amplified and sequenced from a subset of 14 isolates, of which 7 contained MAT1-1-1 and the remaining samples contained MAT1-2-1. A multiplex polymerase chain reaction screen was developed to amplify MAT1-1-1, MAT1-2-1, and a conserved reference gene encoding β-tubulin, and used to screen 784 monoconidial isolates of V. effusa collected from 11 populations of pecan across the southeastern United States. A hierarchical sampling protocol representing region, orchard, and tree allowed for analysis of MAT structure at different spatial scales. Analysis of this collection revealed the frequency of the MAT idiomorphs is in a 1:1 equilibrium of MAT1-1:MAT1-2. The apparent equilibrium of the MAT idiomorphs provides impetus for a renewed effort to search for the sexual stage of V. effusa. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Development and Evaluation of Two Pecan Scab Prediction Models

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1358-1364 ◽  
Author(s):  
A. F. Payne ◽  
D. L. Smith
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Disease Severity ◽  
Model Building ◽  
Prediction Models ◽  
Correlated Data ◽  
Dew Point ◽  
Total Solar Radiation ◽  
Rain Event ◽  
Pecan Scab

Fusicladium effusum (syn. Cladosporium caryigenum), causal agent of pecan scab, is the most economically important pathogen of pecan (Carya illinoinensis). A weather-based advisory is currently used in Oklahoma to assess the need for fungicide application and requires the accumulation of scab hours. A scab hour is defined as an hour with average temperature ≥21.1°C and relative humidity ≥90%. To assess the validity of the thresholds in the advisory, repeated ratings of disease severity were taken on fruit at five locations during the 1994–96 and 2009–10 growing seasons, resulting in a total of eight site years. Hourly weather variables were also examined, including temperature, relative humidity, dew point, dew point depression, total solar radiation, and total rainfall. Rain and disease severity were converted to binomial variables where a rain event (≥2.5 mm) and disease severity (≥25%) were coded as 1 and all other events as 0. Logistic regression models adjusted for correlated data were developed using generalized estimating equations. Two models were developed: a temperature/relative humidity model and a dew point/dew point depression model. For the temperature/relative humidity model, the best fitting model included all main effects. Using this model, validation exercises assuming no rain and total solar radiation of 22.5 MJ m–2 resulted in a 0.45 probability of pecan scab development when the temperature was 21°C and relative humidity was 90%. Findings of this model were further validated during field studies that evaluated different combinations of temperature and relative humidity thresholds for scheduling fungicide applications. These analyses indicated that the current thresholds of temperature and relative humidity are viable, but a modification of the relative humidity component should be considered. For the dew point/dew point depression model, a reduced model, including dew point, dew point depression, and the binomial rain variable, was considered adequate for explaining scab events, which suggests that future model building to describe pecan scab epidemics should include dew point, dew point depression, rain, and total solar radiation as independent variables. This article originally appeared in the January issue, Volume 96, pages 117-123. It was changed to correct errors in a measurement conversion that appeared throughout.

Sign in / Sign up

Export Citation Format

Share Document