Effect of weather factors on the release of ascospores of Uncinula necator, the cause of grape powdery mildew, in the Bordeaux region

1999 ◽  
Vol 77 (7) ◽  
pp. 1044-1051 ◽  
Author(s):  
F Jailloux ◽  
L Willocquet ◽  
L Chapuis ◽  
G Froidefond
Keyword(s):  
Powdery Mildew ◽  
Disease Severity ◽  
Weather Conditions ◽  
Vitis Vinifera L ◽  
Uncinula Necator ◽  
Good Growth ◽  
Bud Burst ◽  
Weather Factors ◽  
Average Temperature ◽  
Ascospore Release

During a 5-year period (1993-1997), the release of Uncinula necator (Schweiniz) Burrill ascospores was monitored under natural conditions in the Bordeaux region. Ascospore release always began after bud burst and generally ended before blossoming. The release periods of ascospores were always associated with a rainfall higher than 2 mm, a wetting duration greater than 2.5 h, an average temperature generally above 11°C and a daily mean temperature sum from November 1 to the first ascospore release above 1100°C. There was no relation between earliness, number of ascospores released, and disease severity on grapes (Vitis vinifera L. cv. Merlot). The primary infection did not appear to be important for the increase of the powdery mildew population; on the other hand, the weather conditions of April (rainfall and temperature) seemed to strongly influence disease severity on berries by enabling good growth of the pathogen on leaves. These findings could be used to determine the optimal dates of the first fungicide treatments for powdery mildew according to the weather conditions.Key words: cleistothecia, ascospores, release, weather conditions, powdery mildew, Uncinula necator, grapevine.

scholarly journals Powdery mildew infection dependent on weather factors in vineyards near Keszthely in 2008

2010 ◽  
Vol 16 (2) ◽  
Author(s):  
P. Taksony ◽  
E. Tarczal ◽  
K. Maráczi ◽  
I. J. Holb ◽  
L. Kocsis
Keyword(s):  
High Temperature ◽  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Meteorological Data ◽  
Weather Conditions ◽  
Vitis Vinifera L ◽  
Weather Factors ◽  
Vegetative Period ◽  
Favorable Conditions ◽  
Powdery Mildew Infection

Weather conditions are extremely influential on grapevine productivity and quality. High temperature and humidity makes favorable conditions for powdery mildew infection respectively. The meteorological data around Keszthely, Hungary show the vegetative period is dryer and warmer than it was closely hundred years ago. We examined the development of powdery mildew infection  on  two variet ies Vitis vinifera L. cv Italian Riesling and cv Merlot in relation with meteorological data. No primer infections were appeared in the vineyard. The year of 2008 was quite ideal for the accumulation of Erysiphe necator in the experimental vineyard. Although the dry summer can lower the infection, but if the high temperature is coupling with rainfall, the possibilities of powdery mildew infection is going to grow higher during the upcoming years.

Release, germination, and pathogenicity of ascospores of Uncinula necator under controlled conditions

1998 ◽  
Vol 76 (5) ◽  
pp. 777-781 ◽  
Author(s):  
F Jailloux ◽  
T Thind ◽  
M Clerjeau
Keyword(s):  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Storage Conditions ◽  
Vitis Vinifera L ◽  
Uncinula Necator ◽  
Grapevine Powdery Mildew ◽  
Germination Ability ◽  
Ascospore Release ◽  
Probable Role ◽  
Leaf Disks

A laboratory technique was standardized for studying the release, maturation, germination, and pathogenicity of ascospores of Uncinula necator (Schw.) Burr. Surface disinfestation and wetting of grape (Vitis vinifera L.) leaf disks bearing cleistothecia collected in the vineyard before incubation in a humid chamber for 48 h at 20°C were found essential for obtaining the release of ascospores (8 ascospores/cm2). Storage conditions involving periodic wetting treatments of cleistothecia at 5°C during 110 days were necessary to induce both ascospore release (80 ascospores/cm2) and germination ability (62%). The matured ascospores were pathogenic on healthy leaf disks at 20°C indicating their probable role as a primary inoculum source. This technique can be helpful in studying the inheritance of characteristics such as pathogenicity and fungicidal resistance.Key words: cleistothecia, ascospores, maturation, germination, pathogenicity, Uncinula necator, grapevine, powdery mildew.

scholarly journals Perennation of Uncinula necator in Vineyards of Eastern Washington

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 242-247 ◽  
Author(s):  
G. G. Grove
Keyword(s):  
Powdery Mildew ◽  
Uncinula Necator ◽  
Bud Burst ◽  
Primary Inoculum ◽  
Dormant Stage ◽  
Ascospore Release ◽  
Rain Events ◽  
Eastern Washington ◽  
Senesced Leaves ◽  
Symptoms And Signs

Studies on the mode of perennation of Uncinula necator in Eastern Washington were conducted over a 4-year period. Evidence of perennation of U. necator in infected dormant buds was not evident during vineyard surveys conducted over the period. Cleistothecia retrieved from bark fissures and senesced leaves contained viable ascospores at bud burst and later. The proportion of cleistothecia retrieved from bark that contained viable ascospores at bud burst ranged from 0.19 to 0.48, 0.09 to 0.72, 0.18 to 0.22, and 0.48 to 0.67 in 1998, 1999, 2000, and 2001, respectively. Viability of cleistothecia retrieved from senesced leaves in two vineyards at bud burst was 0.41 and 0.40 in 1998 and was 0.5 and 0.4 in 1999. Ascospore release in lab studies occurred from the late-dormant stage through the prebloom and (in some cases) the bloom stages. The initial ascosporic infection of Chardonnay leaves began at the late-dormant stage; colony numbers then declined through the prebloom and bloom stages. In vineyard studies, ascospores were trapped as late as 70 days after bud burst during rain events of 3.9 to 9.6 mm. Detection of ascospores in vineyard air preceded the initial occurrence of powdery mildew symptoms and signs and the occurrence of conidia in volumetric spore traps by several days. Cleistothecia are the only known source of primary inoculum in the grape-production regions of Eastern Washington.

Influence of sowing dates on the incidence of powdery mildew of chilli

2017 ◽  
Vol 4 (2) ◽  
Author(s):  
SUDHEENDRA A. ASHTAPUTRE
Keyword(s):  
Powdery Mildew ◽  
Field Experiment ◽  
Disease Severity ◽  
Agricultural Research ◽  
Time Interval ◽  
Research Station ◽  
Inoculum Potential ◽  
Weather Factors ◽  
Agricultural Research Station ◽  
Sowing Dates

A field experiment was conducted during kharif, 2005 at Agricultural Research station, Devihosur, Haveri, Karnataka to assess the progress of powdery mildew at different time interval of sowing dates. Totally 20 different dates of sowings were imposed in the experiment at an interval of 10 days. The crop sown on last week of May to mid of June recorded minimum disease severity compared to rest of the date of sowings. This clearly indicated that crop sown during this period suffers less, which may be due to low inoculum potential, whereas late sown crop suffers more because of the readily available inoculum in the early sown crops. Low disease severity in last week of May to mid of June sowing may be attributed to the non-congenial weather factors for the development of the disease.

RELATIONSHIP BETWEEN WEATHER FACTORS AND DOLLAR SPOT OF CREEPING BENTGRASS

1984 ◽  
Vol 64 (1) ◽  
pp. 167-174 ◽  
Author(s):  
ROBERT HALL
Keyword(s):  
Disease Control ◽  
Creeping Bentgrass ◽  
Weather Conditions ◽  
Acceptable Level ◽  
Sclerotinia Homoeocarpa ◽  
Agrostis Palustris ◽  
Dollar Spot ◽  
Weather Factors ◽  
Average Temperature

In 1981 and 1982 epidemics of dollar spot of creeping bentgrass, caused by Sclerotinia homoeocarpa, proceeded in a series of steps. Each step began at a point where a decline in the epidemic rate was followed by an increase in the epidemic rate and continued until a new step began. A step in the epidemic occurred after two consecutive wet days if the average temperature for the period was at or above 22 °C or after three or more consecutive wet days if the average temperature for the period was 15 °C or greater. These weather conditions were referred to as "infection periods." In 1982, an application of Tersan 1991 (benomyl) 1 and 2 days after two infection periods provided an acceptable level of disease control as effective as that obtained from a regular preventive schedule of seven sprays.Key words: Agrostis palustris, disease control, Sclerotinia homoeocarpa, weather-timed spray

Development of SCAR markers linked to powdery mildew (Uncinula necator) resistance in grapevine (Vitis vinifera L. and Vitis sp.)

2006 ◽  
Vol 19 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Murat Akkurt ◽  
Leocir Welter ◽  
Erika Maul ◽  
Reinhard Töpfer ◽  
Eva Zyprian
Keyword(s):  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Vitis Vinifera L ◽  
Uncinula Necator ◽  
Scar Markers ◽  
Vitis Sp

scholarly journals Foliar Sprays of Clay Reduce the Severity of Powdery Mildew on Long English Cucumber and Wine Grapes

HortScience ◽  
2001 ◽  
Vol 36 (5) ◽  
pp. 934-936 ◽  
Author(s):  
David L. Ehret ◽  
Carol Koch ◽  
Jim Menzies ◽  
Peter Sholberg ◽  
Tim Garland
Keyword(s):  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Cucumis Sativus ◽  
Disease Severity ◽  
Fruit Quality ◽  
Leaf Surface ◽  
Uncinula Necator ◽  
Sphaerotheca Fuliginea ◽  
Wine Grapes ◽  
Foliar Sprays

Foliar sprays of a nonswelling chlorite mica clay were applied to leaves of greenhouse-grown long English cucumber (Cucumis sativus L.) plants, either before or after an artificial inoculation with powdery mildew [Sphaerotheca fuliginea (Schlech.:Fr.) Poll.] and to field-grown wine grapes (Vitis vinifera L.) before natural inoculation with powdery mildew [Uncinula necator (Schwein.) Burrill]. In all cases, the clay sprays did not eradicate the pathogen, but resulted in significant reductions in disease severity. In cucumber, a single spray of 0.5% clay reduced colony numbers on leaves by up to 60%. Spraying after inoculation was generally more effective than spraying before inoculation. In grapes, repeated sprays of either 2% or 4% clay were applied through the season to `Reisling' and `Chancellor' vines. Four percent clay reduced the amount of leaf surface covered by mildew by 22% in `Reisling' and 51% in `Chancellor'. Both concentrations reduced the incidence of mildew on clusters and canes. No treatment effects were observed on fruit quality. Our results demonstrate that foliar sprays of clay can reduce the severity of Sphaerotheca fuliginea and Uncinula necator on cucumbers and grapes, respectively.

scholarly journals The dynamics of powdery mildew development on pumpkins

2019 ◽  
pp. 111-123
Author(s):  
S. Mykhailenko ◽  
O. Melnyk
Keyword(s):  
Powdery Mildew ◽  
Disease Severity ◽  
Weather Conditions ◽  
Disease Spread ◽  
Forest Steppe ◽  
Erysiphe Cichoracearum ◽  
Significant Difference ◽  
Severity Of The Disease ◽  
The Right ◽  
Powdery Mildew Infection

Goal. To determine the spread and development of powdery mildew on pumpkins in the Forest-Steppe of Ukraine. Methods of investigation. The experiments were carried out in 2016—2018 biennium in the Right-Bank Forest Steppe of Ukraine (Khmelnytsky region) on the following varieties: common pumpkins — Ukrainskyi bahatoplidnyi, hull-less — Shtyriiskyi. Assessment of severity and spread of powdery mildew was carried out by conventional methods. The records were taken by visual method at 51, 73 and 89 stages (BBCH scale). Ten plants per plot were selected and spread and severity of the disease in percentage were determined. Results of investigation. During the period of investigation, powdery mildew was observed on the pumpkins of both varieties annually. Its first sympthoms were noted at the 15—17 stage. According to the morphological and biometric features, the pathogen identified as Erysiphe cichoracearum (DC.) V.P. Heluta. In the varieties studied, powdery mildew was found with a non-significant difference in severity and spread. In 2016, the severity of powdery mildew on pumpkins of variety Ukrainskyi bahatoplidnyi varied in the range of 15.4—19.5%, disease spread — 45.1—49.6%, on variety Shtyriiskyi development was 13.3—17.5%, distribution — 46.2—48.1%. In 2017, we obtained the following results: the disease severity for common pumpkins was in the range 13.2—17.4%, disease spread — 42.8—46.7%, for hull-less pumpkins disease severity was 12.2—16.8%, disease spread — 41.7—45.3%. In 2018, severity of powdery mildew was higher than in previous years, accounting for 21.2—26.7% with spread 50.4—55.2% on common pumpkins, and 19.4—25.3% with spread 48.8—54.2% on hull-less pumpkins. The correlation analysis of the data showed that the closest correlation between the spread and the development of the disease was observed with the precipitation and GTC in June. Conclusions. Dynamics of severity of powdery mildew during 2016—2018 years on common and hull-less pumpkins were studied. At stage of full ripening, the maximum rates of spread and severity of the disease were noted, which averaged 49.2—50.5% and 19.9—21.2% over the three years, respectively. No significant difference in the powdery mildew infection between common pumpkins (variety Ukrainskyi bahatoplidnyi) and hull-less pumpkins (variety Shtyriiskyi) was found. The defining conditions for the development of powdery mildew on pumpkins are the weather conditions in June, most notably the presence of increased moisture during this period.

scholarly journals Disease–Weather Relationships for Powdery Mildew and Yellow Rust on Winter Wheat

2008 ◽  
Vol 98 (5) ◽  
pp. 609-617 ◽  
Author(s):  
D. E. Te Beest ◽  
N. D. Paveley ◽  
M. W. Shaw ◽  
F. van den Bosch
Keyword(s):  
Powdery Mildew ◽  
Winter Wheat ◽  
Disease Severity ◽  
Field Experiments ◽  
Yellow Rust ◽  
Influential Factor ◽  
Weather Factors ◽  
Initial Inoculum ◽  
Qualitative Models ◽  
The Uk

Key weather factors determining the occurrence and severity of powdery mildew and yellow rust epidemics on winter wheat were identified. Empirical models were formulated to qualitatively predict a damaging epidemic (>5% severity) and quantitatively predict the disease severity given a damaging epidemic occurred. The disease data used was from field experiments at 12 locations in the UK covering the period from 1994 to 2002 with matching data from weather stations within a 5 km range. Wind in December to February was the most influential factor for a damaging epidemic of powdery mildew. Disease severity was best identified by a model with temperature, humidity, and rain in April to June. For yellow rust, the temperature in February to June was the most influential factor for a damaging epidemic as well as for disease severity. The qualitative models identified favorable circumstances for damaging epidemics, but damaging epidemics did not always occur in such circumstances, probably due to other factors such as the availability of initial inoculum and cultivar resistance.

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