scholarly journals The Behaviour of Some Grapevine Varieties to the Guignardia bidwellii Fungus Attack

2020 ◽  
Vol 77 (1) ◽  
pp. 122
Author(s):  
Liliana TOMOIAGA ◽  
Veronica Sanda CHEDEA
Keyword(s):  
Climatic Conditions ◽  
Black Rot ◽  
Guignardia Bidwellii ◽  
Tolerance Testing

Guignardia bidwellii or black rot of vine is one of the most dangerous diseases that occur in vineyards in the center of Transylvania. The objective of this work was the tolerance testing of varieties and clones homologated at SCDVV Blaj to the Guignardia bidwellii attack. The behavior of vine varieties to the Guignardia bidwellii fungus attack was characterized by the analysis of the severity of the symptoms according to a scale in function of the attack degree (AD). The results obtained revealed the tolerance of the tested varieties: ‘Rubin’ (AD=0.13%), ‘Amurg’ (AD=0.25%), ‘Brumariu’ (AD=0.78%), ‘Radames’ (AD=0.96%) and ‘Blasius’ (AD=0.97%), a medium tolerance presented ‘Selena’ (AD=9.28%) variety and ‘Neuburger-10 Bl’ (AD=5.04%), ‘Iordana 9-1 Bl’ (AD=6.40%), ‘Riesling de Rhin 7-2’ (AD=7.2%), ‘Sauvignon-9 Bl’ (AD=9.28%), ‘Traminer roz-60 B’ clones (AD=17.5%) and susceptibility for ‘Astra’ variety (AD=25.56%) and ‘Riesling italian-3 Bl’ (AD=22.4%), ‘Pinot gris-34 Bl’ (AD=30.60%), ‘Feteasca regala-21 Bl’ (AD=31.50%), ‘Muscat Ottonel-12Bl’ (AD=35.30%), ‘Feteasca alba-29 Bl’ clones (AD=38.40%). The results obtained regarding the behavior of grapevine in the climatic conditions specific to the studied area for the 2016-2018 period, show that the lowest values of AD were registered for the ‘Rubin’ (AD=0.13%), ‘Amurg’ (AD=0.25%), ‘Brumariu’ (AD=0.78%), ‘Radames’ (AD=0.96%) and ‘Blasius’ (AD=0.97%) varieties homologated at SCDVV Blaj.

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 Development of a method for phenotyping Black Rot (Guignardia bidwellii) resistance on grapevine (Vitis_ spp.)

2011 ◽  
Author(s):  
Friederike Rex ◽  
Iris Fechter ◽  
Ludger Hausmann ◽  
Reinhard Töpfer
Keyword(s):  
Black Rot ◽  
Guignardia Bidwellii

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 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 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.

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