scholarly journals Production of Pycnidia and Conidia by Guignardia bidwellii, the Causal Agent of Grape Black Rot, as Affected by Temperature and Humidity

2017 ◽  
Vol 107 (2) ◽  
pp. 173-183 ◽  
Author(s):  
G. Onesti ◽  
E. González-Domínguez ◽  
V. Rossi
Keyword(s):  
Field Experiments ◽  
Growth Parameters ◽  
Effect Of Temperature ◽  
Black Rot ◽  
High Humidity ◽  
Guignardia Bidwellii ◽  
Leaf Lesion ◽  
Grape Black Rot ◽  
Effects Of Temperature ◽  
Grape Leaf

Black rot, caused by the fungus Guignardia bidwellii, is a polycyclic disease affecting grape leaves and berries. In environmentally controlled experiments and in a 3-year field study, the effects of temperature and relative humidity (RH) were assessed on the following growth parameters of G. bidwellii: (i) formation of pycnidia and cirri in grape leaf lesions, (ii) production and germination of conidia, and (iii) length of the period between lesion appearance and pycnidia production. Pycnidia were produced between 5 and 35°C and at 90 to 100% RH but more pycnidia were produced between 20 and 30°C. No pycnidia were produced at RH < 90%. The first pycnidia were produced in approximately 2 days after lesion appearance at ≥20°C and in 8 days at 5°C; pycnidia continued to be produced on the same lesion for 5 to 16 days after lesion appearance, depending on the temperature. Models were developed to describe the effect of temperature and RH on pycnidia production, accounting for 95 and 97% of variability, respectively. Cirri were extruded only between 15 and 35°C and mainly at 100% RH. Field experiments confirmed that pycnidia are produced for several days on a leaf lesion and that the length of the period between lesion appearance and pycnidia production depends on temperature. Overall, the findings showed that production of conidia requires high humidity; under field conditions, some hours at high humidity, which usually occur at nighttime, rather than constant high humidity may be sufficient.

scholarly journals THE EFFECT OF POST PLANT SOIL SOLARIZATION ON BLACK ROT OF 'CARLOS' MUSCADINE GRAPE

HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1169f-1169
Author(s):  
C. Stevens ◽  
V. A. Khan ◽  
J. Y. Lu ◽  
M. A. Wilson ◽  
Z. Haung ◽  
...  
Keyword(s):  
Growth Response ◽  
Lesion Size ◽  
Soil Solarization ◽  
Black Rot ◽  
Plastic Mulch ◽  
Vitis Rotundifolia ◽  
Guignardia Bidwellii ◽  
Plant Soil ◽  
Leaf Lesion ◽  
High Soil Temperature

In 1988 and 1989 a muscadine vineyard at Tuskegeee, Alabama was treated by post plant soil solarization (PSS) (covering of moist soil around 'Carlos' muscadine plants (Vitis rotundifolia Michx.) with clear polyethylene plastic mulch to achieve high soil temperature for 30 and 75 days, respectively during PSS. Grape plants grown in solarized soils showed increases in growth response such as increased yield. Foliage of grape plants was evaluated for reaction to black rot incited by Guignardia bidwellii. A significant reduction of the foliage disease black rot was observed. The number of lesions per leaf, lesion size and percent leaves with lesions were significantly reduced by as much as 56% up to three years after solarization.

scholarly journals A Cumulative Degree-Day-Based Model to Calculate the Duration of the Incubation Period of Guignardia bidwellii

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1054-1059 ◽  
Author(s):  
Daniel Molitor ◽  
Cathleen Fruehauf ◽  
Ottmar Baus ◽  
Beate Berkelmann-Loehnertz
Keyword(s):  
Incubation Period ◽  
Present Model ◽  
Developmental Stages ◽  
Black Rot ◽  
Phenological Stage ◽  
Degree Days ◽  
Fungal Development ◽  
Guignardia Bidwellii ◽  
Degree Day ◽  
Grape Black Rot

The duration of the incubation period of Guignardia bidwellii on leaves and clusters of Vitis vinifera strongly correlates to temperature. To describe this relationship mathematically, a new, cumulative degreeday- based model was developed. According to this model, first symptoms on leaves appear after reaching a threshold of 175 cumulative degree-days (calculated as the sum of average daily temperatures between 6 and 24°C starting on the day after the infection). On clusters, the duration of the incubation period is additionally affected by their respective developmental stages. For ‘Riesling’, the duration of the incubation period on clusters corresponds to the duration on leaves until reaching the phenological stage “berries beginning to touch“ but extends continuously with ongoing phenological development. Therefore, a correction factor recognizing cluster phenology was derived to calculate the cumulative degree-day thresholds for the occurrence of first symptoms on clusters after reaching “majority of berries touching”. Hence, this present model allows the estimation of fungal development and forecasts the appearance of new symptoms on leaves as well as on clusters, enabling growers to more precisely schedule curative as well as protective fungicide applications against grape black rot.

scholarly journals Factors Influencing the Efficacy of Myclobutanil and Azoxystrobin for Control of Grape Black Rot

Plant Disease ◽  
2003 ◽  
Vol 87 (3) ◽  
pp. 273-281 ◽  
Author(s):  
Lisa Emele Hoffman ◽  
Wayne F. Wilcox
Keyword(s):  
Black Rot ◽  
Alternative Respiration ◽  
Complete Control ◽  
Guignardia Bidwellii ◽  
Factors Influencing ◽  
Grape Black Rot ◽  
History Of ◽  
Commercial Vineyard ◽  
Strobilurin Fungicide

We studied several factors influencing the efficacy of the demethylation inhibitor (DMI) fungicide myclobutanil and the strobilurin fungicide azoxystrobin for control of grape black rot, caused by the pathogen Guignardia bidwellii (anamorph Phyllosticta ampelicida). The distribution of sensitivities to myclobutanil among G. bidwellii isolates from an “organic” vineyard (no previous exposure to synthetic fungicides, n = 50) and from a commercial vineyard with a history of DMI applications (n = 60) was determined in vitro. There was little difference between the two populations, and the range of sensitivities was narrow; for the composite population of 110 isolates, the value of the mean effective dose for 50% inhibition (ED50) was 0.04 mg/liter, and the most- and least-sensitive isolates were separated by a factor of 16. When applied from 2 to 6 days after inoculating grape seedlings with a suspension containing either 2 × 104 or 1 × 106 conidia per ml, myclobutanil (60 mg/liter) provided complete control of lesion development. When applied beyond 6 days after inoculation but prior to lesion appearance (9 to 11 days after inoculation, depending on temperature), it provided complete control of pycnidium production in those lesions that developed subsequently. In contrast, when applied 2 to 10 days after inoculation with 2 × 104 conidia per ml, azoxystrobin (128 mg/liter) provided only 78 to 63% control of lesion formation and erratic control of pycnidium formation, although conidium production was reduced by 85 to 68% across this range of treatments. Relatively little control was provided by azoxystrobin treatments following inoculation with 1 × 106 conidia per ml. On leaf disks treated with azoxystrobin at 20 mg/liter prior to inoculation, 8 to 43% of conidia from five G. bidwellii isolates germinated, and 4 to 19% formed appressoria. However, these processes were completely to near-completely inhibited when salicylhydroxamic acid (SHAM), which inhibits an alternative respiration pathway utilized to circumvent the activity of strobilurin fungicides, was added to the inoculum at 100 mg/liter. Thus, alternative respiration apparently allowed the conidia to germinate and form appressoria on azoxystrobin-treated leaves. When grape seedlings were sprayed with commercially formulated azoxystrobin at 200 mg/liter and inoculated the next day with G. bidwellii conidia, little or no disease was evident 4 weeks later. However, G. bidwellii pycnidia formed on up to 50% of the leaves from such plants when they were killed with paraquat 1 to 7 days after inoculation. These results suggest that latent infections became established on azoxystrobin-treated leaves and became active after the plants were killed with paraquat.

scholarly journals Influence of Grape Berry Age on Susceptibility to Guignardia bidwellii and Its Incubation Period Length

2002 ◽  
Vol 92 (10) ◽  
pp. 1068-1076 ◽  
Author(s):  
Lisa Emele Hoffman ◽  
Wayne F. Wilcox ◽  
David M. Gadoury ◽  
Robert C. Seem
Keyword(s):  
Incubation Period ◽  
Epidemiological Studies ◽  
Grape Berry ◽  
Period Length ◽  
Black Rot ◽  
Variable Effect ◽  
Guignardia Bidwellii ◽  
Age Related ◽  
Vitis Labruscana ◽  
Grape Black Rot

The period of fruit susceptibility to Guignardia bidwellii (anamorph Phyllosticta ampelicida), the causal agent of grape black rot, was determined in the field. Intact fruit were inoculated weekly from bloom until 8 weeks later with a suspension containing 2 × 105 conidia per ml. Disease progress was monitored approximately every 2 days until 3 to 5 weeks after inoculation, depending on the year and variety. Fruit of Vitis × labruscana ‘Concord’ exhibited a period of maximum susceptibility from midbloom until 2 to 4 weeks later, although some berries became symptomatic when inoculated 4 to 5 weeks postbloom. Fruit of V. vinifera ‘Chardonnay’ and ‘Riesling’ exhibited a period of maximum susceptibility from midbloom until 3 to 5 weeks later, although some berries retained their susceptibility until 6 to 7 weeks postbloom. These susceptible periods were approximately 2 to 4 weeks shorter than previously assumed. Fruit age at the time of inoculation affected the length of the incubation period (time from inoculation until symptom appearance). When the incubation period was defined in terms of degree hours (base = 0°C) accumulated after inoculation, DH50 values (the number of degree hours required to reach 50% of final disease severity) increased by at least 50% as berries neared the end of their susceptible period. Newly symptomatic berries continued to appear for over 1 month after inoculation of older fruit. Thus, age-related or ontogenic, host resistance was manifested as both a decline in susceptibility and a significant increase in incubation period length. The control of black rot is likely to be improved by tailoring the intensity of fungicidal protection to the abbreviated period of fruit susceptibility defined in this study. Furthermore, the efficacy of management programs and the results of epidemiological studies are likely to be misinterpreted unless the variable effect of fruit age on incubation period length is recognized.

scholarly journals Integrated Control of Grape Black Rot: Influence of Host Phenology, Inoculum Availability, Sanitation, and Spray Timing

2004 ◽  
Vol 94 (6) ◽  
pp. 641-650 ◽  
Author(s):  
Lisa Emele Hoffman ◽  
Wayne F. Wilcox ◽  
David M. Gadoury ◽  
Robert C. Seem ◽  
Duane G. Riegel
Keyword(s):  
Integrated Control ◽  
Black Rot ◽  
Complete Control ◽  
Guignardia Bidwellii ◽  
Grape Black Rot ◽  
Host Phenology ◽  
Spray Timing ◽  
Spray Regimes ◽  
Disease Pressure ◽  
And Control

The epidemiology and control of black rot (Guignardia bidwellii) was studied from 1995 to 1999 in vineyards in Dresden and Naples, NY, where disease pressure was moderate and extreme, respectively. The efficacy of serial applications of myclobutanil, provided at 2-week intervals and varied with respect to their number and time of initiation, was examined within the context of host phenology, inoculum availability, and sanitation. At Dresden, sprays applied over 4 weeks through the immediate prebloom stage provided only 13 to 91% control of diseased clusters, despite the release of 95% of the season's ascosporic inoculum during the period of fungicidal protection. However, applications immediately prior to bloom plus 2 and 4 weeks later, which afforded protection while fruit are highly susceptible to infection, provided virtually complete control. At Naples, where mummified berries were retained in the canopy after mechanical pruning, this same regime provided only approximately 80% disease control, but applying a fourth spray 2 weeks prebloom generally improved control. Hand-pruning mummies to the ground in selected plots significantly (P ≤ 0.05) improved control in some spray regimes. Although this sanitation practice did not affect inoculum dynamics through bloom, very few spores were recovered thereafter from mummies collected from the ground, whereas abundant ascospores and conidia were recovered from mummies in the trellis for an additional 6 to 8 weeks.

Effect of temperature during the synthesis process of CdSe nanoparticles using the colloidal technique

MRS Advances ◽  
2020 ◽  
Vol 5 (63) ◽  
pp. 3389-3395
Author(s):  
R. González-Díaz ◽  
D. Fernández-Sánchez ◽  
P. Rosendo-Francisco ◽  
G. Sánchez-Legorreta
Keyword(s):  
Scanning Tunneling Microscope ◽  
Electron Cloud ◽  
Cdse Nanoparticles ◽  
Effect Of Temperature ◽  
Synthesis Process ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
First Results ◽  
Effects Of Temperature ◽  
Scanning Electron

AbstractIn this work, the first results of the effects of temperature during the production of Se2- ions and the effect during the interaction of Cd2+ and Se2- ions in the synthesis process of CdSe nanoparticles are presented. The synthesis of CdSe was carried out by the colloidal technique, in the first one we used a temperature of 63 °C to produce Se2- ions and in the second one an interaction temperature of 49 °C. The samples were characterized using a Scanning Electron Microscope (SEM) and a Scanning Tunneling Microscope (STM). From the SEM micrographs it was possible to identify the thorns formation and irregular islands. STM micrographs reveal elliptical shapes with a regular electron cloud profile.

scholarly journals Quantitative Characterization of Geotrichum candidum Growth in Milk

2021 ◽  
Vol 11 (10) ◽  
pp. 4619
Author(s):  
Petra Šipošová ◽  
Martina Koňuchová ◽  
Ľubomír Valík ◽  
Monika Trebichavská ◽  
Alžbeta Medveďová
Keyword(s):  
Growth Parameters ◽  
Mechanistic Model ◽  
Geotrichum Candidum ◽  
Activity Level ◽  
Effect Of Temperature ◽  
Operational Parameters ◽  
Quantitative Characterization ◽  
Essential Knowledge ◽  
Cardinal Temperatures

The study of microbial growth in relation to food environments provides essential knowledge for food quality control. With respect to its significance in the dairy industry, the growth of Geotrichum candidum isolate J in milk without and with 1% NaCl was investigated under isothermal conditions ranging from 6 to 37 °C. The mechanistic model by Baranyi and Roberts was used to fit the fungal counts over time and to estimate the growth parameters of the isolate. The effect of temperature on the growth of G. candidum in milk was modelled with the cardinal models, and the cardinal temperatures were calculated as Tmin = −3.8–0.0 °C, Topt = 28.0–34.6 °C, and Tmax = 35.2–37.2 °C. The growth of G. candidum J was slightly faster in milk with 1% NaCl and in temperature regions under 21 °C. However, in a temperature range that was close to the optimum, its growth was slightly inhibited by the lowered water activity level. The present study provides useful cultivation data for understanding the behaviour of G. candidum in milk and can serve as an effective tool for assessing the risk of fungal spoilage, predicting the shelf life of dairy products, or assessing the optimal conditions for its growth in relation to the operational parameters in dairy practices.

Sign in / Sign up

Export Citation Format

Share Document