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 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 Effect of Temperature on the Incubation Period and Leaf Colonization in Bacterial Blight of Anthurium

1999 ◽  
Vol 89 (11) ◽  
pp. 1007-1014 ◽  
Author(s):  
R. Fukui ◽  
H. Fukui ◽  
A. M. Alvarez
Keyword(s):  
Linear Relationship ◽  
Leaf Area ◽  
Incubation Period ◽  
Xanthomonas Campestris ◽  
Resistant Cultivar ◽  
Effect Of Temperature ◽  
Susceptible Cultivar ◽  
Degree Days ◽  
Degree Day ◽  
Leaf Tissues

Effect of temperature on leaf colonization in anthurium blight was studied using a bioluminescent strain of Xanthomonas campestris pv. dieffenbachiae. In a susceptible cultivar, colonization of leaf tissues (monitored by detection of bioluminescence) and symptom development (assessed visually) advanced rapidly at higher temperatures. For a susceptible cultivar, there was a linear relationship between degree-days and percent leaf area colonized by the pathogen, indicating that leaf colonization in a susceptible cultivar was a direct function of the cumulative effect of temperature. The degree-day intercept of the regression line represented the time from inoculation to detection of bioluminescence, and the slope indicated the increase of leaf colonization per degree-day. There also was a linear relationship between the logarithm of degree-days and the logarithm of percent leaf area showing visible symptoms in a susceptible cultivar. The degree-day intercept of this relationship represented the incubation period (about 500 degree-days). The degree-days required to detect bioluminescence was not considerably different between susceptible and resistant cultivars. However, the subsequent rates of leaf colonization were significantly lower for a resistant cultivar than for a susceptible cultivar in all temperature regimes. The results suggest that multiplication of the pathogen in the leaf tissues is optimized in the susceptible cultivar. In contrast, in the resistant cultivar, the defense mechanisms overshadow the temperature effect. The differential response to temperatures may be an additional indicator of cultivar susceptibility.

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 Improving the Prediction of Processing Bean Maturity Based on the Growing-degree Day Approach

HortScience ◽  
2000 ◽  
Vol 35 (7) ◽  
pp. 1234-1237 ◽  
Author(s):  
Sylvie Jenni ◽  
Gaétan Bourgeois ◽  
Hélène Laurence ◽  
Geneviève Roy ◽  
Nicolas Tremblay
Keyword(s):  
Phaseolus Vulgaris ◽  
Prediction Model ◽  
Coefficient Of Variation ◽  
Developmental Stages ◽  
Growing Degree Days ◽  
Base Temperature ◽  
Degree Days ◽  
Snap Bean ◽  
Degree Day ◽  
Common Base

Four snap bean (Phaseolus vulgaris L.) cultivars, Goldrush, Teseo, Labrador, and Flevoro, were grown in irrigated fields of southern Quebec between 1985 and 1998. Data on phenology collected from these fields were used to determine which base temperature would best predict time from sowing to maturity. The optimal base temperature was 0 °C for `Goldrush', `Teseo', and `Labrador' and 6.7 °C for `Flevoro'. Adjusting different base temperatures for intermediate developmental stages (emergence, flowering) did not improve the prediction model. All years for a given cultivar were then used to determine the base temperature with the lowest coefficient of variation (CV) for predicting the time from sowing to maturity. A common base temperature of 0 °C was selected for all cultivars, since `Flevoro' was not very sensitive to changes in base temperature. This method improved the prediction of maturity compared with the conventional computation growing-degree days (GDD) with a base of 10 °C. For the years and cultivars used in this study, calculating GDD with a base of 0 °C gave an overall prediction of maturity of 1.7, 1.5, 2.0, and 1.4 days based on average absolute differences, for `Flevoro', `Goldrush', `Teseo', and `Labrador', respectively.

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 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.

Phenology of the sugar beet weevil, Bothynoderes punctiventris Germar (Coleoptera: Curculionidae), in Croatia

2018 ◽  
Vol 109 (4) ◽  
pp. 518-527
Author(s):  
Z. Drmić ◽  
M. Čačija ◽  
H. Virić Gašparić ◽  
D. Lemić ◽  
R. Bažok
Keyword(s):  
Sugar Beet ◽  
Dynamic Models ◽  
Developmental Stages ◽  
Adult Population ◽  
Regional Scale ◽  
Adult Emergence ◽  
Soil Samples ◽  
Population Characteristics ◽  
Degree Day ◽  
Development Threshold

AbstractThe sugar beet weevil (SBW), Bothynoderes punctiventris Germar, 1824, is a significant pest in most of Eastern Europe. Here, the SBW is described and its seasonal activity characterized, in terms of its different developmental stages in relation to Julian days (JDs), degree-day accumulations (DDAs), and precipitation, as a key to improving monitoring and forecasting of the pest. The phenology and population characteristics of SBW were investigated in sugar beet fields in eastern Croatia over a 4-year period (2012–2015). By using the degree-day model (lower development threshold of 5°C, no upper development threshold, biofix 1 January), the first emergence of overwintering adults was determined as becoming established when the DDA reached 20. The adult emergence was completed when the DDA reached 428. SBW males emerged first, following which the females dominated the adult population. Overwintering adults were present in the field until early July. In August, adults of the offspring generation began to appear. The eggs laid by the overwintering generation required, on average, 10–15 days to develop into larvae; however, eggs were found in soil samples over a period of 102 days (between JDs 112 and 214). Larvae were present in the soil samples over a period of a maximum of 143 days (the first larvae were established on JD 122 and the last one on JD 265), and pupae were established in the soil over a period of 102 days (between JDs 143 and 245). This study provides important data for understanding SBW population dynamics and developing potential population dynamic models for pest forecasting on a regional scale.

scholarly journals Pengaruh Suhu terhadap Perkembangan Pradewasa Parasitoid Eriborus argenteopilosus Cameron (Hymenoptera: Ichneumonidae)

2012 ◽  
Vol 13 (3) ◽  
pp. 250
Author(s):  
Novri Nelly ◽  
Trimurti Habazar ◽  
Rahmat Syahni ◽  
Damayanti Buchori
Keyword(s):  
Survival Rate ◽  
Temperature Effect ◽  
Development Time ◽  
Degree Days ◽  
Degree Day ◽  
Adult Parasitoid ◽  
Different Temperatures ◽  
Lepidoptera Pyralidae

Temperature effect on development time of the preadult parasitoid Eriborus argenteopilosus Cameron(Hymenoptera: Ichneumonidae) were studied to know development time, degree days and survival rate.Crocidolomia pavonana (Fabricius)(Lepidoptera: Pyralidae) larvae was exposed to E. argenteopilosus female andreared at four different temperatures i.e 160C, 200C, 250C and 300C. Data were analyzed using anova and linearregression to calculate degree day. At 200C E. argenteopilosus showed the highest degree day and survival rate(18.67 %), while at 300C nothing adult parasitoid emergenced. Degree day to development time of parasitoid attemperature 200C i.e fase egg-adult: 300.05; egg-pupae 173.35; pupae-adult 171.

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