scholarly journals Suppression of Grapevine Powdery Mildew by a Mycophagous Mite

Plant Disease ◽  
2005 ◽  
Vol 89 (12) ◽  
pp. 1331-1338 ◽  
Author(s):  
Heather S. Melidossian ◽  
Robert C. Seem ◽  
Greg English-Loeb ◽  
Wayne F. Wilcox ◽  
David M. Gadoury
Keyword(s):  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Uncinula Necator ◽  
Laboratory Studies ◽  
Rapid Loss ◽  
Infection Efficiency ◽  
Grapevine Powdery Mildew ◽  
Grape Powdery Mildew

Orthotydeus lambi reduced the severity of grape powdery mildew (Uncinula necator) on fruit and foliage of Vitis vinifera ‘Chardonnay’ and ‘Riesling’ in repeated field and laboratory trials. Vines were infested with O. lambi at two densities (5 or 30 mites per leaf) at each of two times (2 to 3 weeks prebloom and 1 week postbloom). Overall, powdery mildew on the berries and foliage was suppressed by early (prebloom) mite releases at both densities, but only by the higher density in late (postbloom) releases. In a separate trial, when foliage was infested at 30 mites per leaf but mites were excluded from certain fruit clusters, severity of powdery mildew was significantly reduced on the mite-free clusters of mite-infested shoots. Thus, O. lambi may suppress powdery mildew on the fruit by reducing inoculum from foliar infections. In laboratory studies, both immature and mature mites reduced infection efficiency, colony expansion, and sporulation of the mildew colonies; but immature mites were more voracious feeders, consuming more pathogen biomass per unit of mite biomass. Mites tore at the mycelium and conidia with their palps during feeding, leading to leakage, rapid loss of hyphal turgor, and collapse of hyphae.

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.

Uncinula necator. [Descriptions of Fungi and Bacteria].

1967 ◽  
Author(s):  
J. N. Kapoor
Keyword(s):  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Geographical Distribution ◽  
World Wide ◽  
Uncinula Necator

Abstract A description is provided for Uncinula necator. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Vitis spp., chiefly Vitis vinifera; also on Parthenocissus spp., Ampelopsis spp. DISEASE: Powdery mildew of vine. GEOGRAPHICAL DISTRIBUTION: World-wide. TRANSMISSION: Conidia and mycelium overwinter in diseased buds, fallen berries or on overwintered stems. Cleistothecia, when formed, are capable of overwintering (Blumer, 1967).

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 Efficacy of Biopesticides and Leaf Removal in Grapevine Powdery Mildew Management

2016 ◽  
Vol 17 (2) ◽  
pp. 84-91
Author(s):  
Michelle M. Moyer ◽  
Jensena M. Newhouse ◽  
Gary G. Grove
Keyword(s):  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Disease Control ◽  
Fungicide Resistance ◽  
Cultural Practices ◽  
Resistance Management ◽  
Leaf Removal ◽  
Control Programs ◽  
Bloom Period ◽  
Grapevine Powdery Mildew

Integrating biological-based fungicides into conventional spray programs may help with fungicide resistance management. However, little is known about how to best integrate these products while still maintaining maximum disease control. Programs with as few as one synthetic fungicide or as many as three synthetic fungicides added to a biopesticide-based rotation during the bloom period of Vitis vinifera had significantly better disease control than a biopesticide-only-based program. When integrated with different timings of fruit-zone leaf removal, specific combinations of biopesticide programs and fruit-zone leaf removal enhanced the efficacy of that program to be on par with disease control seen in a program entirely based on synthetic fungicides. This suggests that when designing a fungicide program using biopesticides as a base, the addition of a synthetic fungicide during the window of ontogenic susceptibility in clusters and the adoption of cultural practices such as leaf removal can significantly improve the efficacy of that program. Accepted for publication 11 April 2016. Published 20 April 2016.

scholarly journals Distributions of Sensitivities to Three Sterol Demethylation Inhibitor Fungicides Among Populations of Uncinula necator Sensitive and Resistant to Triadimefon

1997 ◽  
Vol 87 (8) ◽  
pp. 784-791 ◽  
Author(s):  
Eugene O. Erickson ◽  
Wayne F. Wilcox
Keyword(s):  
Powdery Mildew ◽  
Active Form ◽  
Correlation Coefficients ◽  
The Other ◽  
Cross Resistance ◽  
Uncinula Necator ◽  
Previous Exposure ◽  
Grapevine Powdery Mildew ◽  
Dmi Fungicides ◽  
Demethylation Inhibitor

Single-conidial isolates of Uncinula necator from (i) a population representing two vineyards with no previous exposure to sterol demethylation inhibitor (DMI) fungicides (“unexposed,” n = 77) and (ii) a population representing two vineyards in which powdery mildew was poorly controlled by triadimefon after prolonged DMI use (“selected,” n = 82) were assayed to determine distributions of sensitivities to the DMI fungicides triadimenol (the active form of triadimefon), myclobutanil, and fenarimol. Median 50% effective dose (ED50) values (micrograms per milliliter) in the selected versus unexposed populations were 0.06 versus 1.9 for triadimenol, 0.03 versus 0.23 for myclobutanil, and 0.03 versus 0.07 for fenarimol, respectively. Isolates were grouped into sensitivity classes according to their ED50 values, and those from the selected population were categorized as resistant if the frequency of their sensitivity class had increased significantly relative to levels found in the unexposed population (ED50 values exceeding 0.56, 0.18, and 0.18 μg/ml for triadimenol, myclobutanil, and fenarimol, respectively). Of the 76 isolates defined as resistant to triadimenol, 64% were classified as cross-resistant to myclobutanil, 18% were classified as cross-resistant to fenarimol, and 17% were classified as resistant to all three fungicides; 25% of the isolates classified as resistant to myclobutanil also were classified as resistant to fenarimol. Similar cross-resistance relationships were revealed when all isolates were examined by regressing log ED50 values for each fungicide against those for the remaining two fungicides to determine the correlation coefficients (e.g., r = 0.85 for triadimenol versus myclobutanil and 0.56 for triadimenol versus fenarimol). The restricted levels of cross-resistance indicated by these data, particularly between fenarimol and the other two fungicides, is in sharp contrast to the high levels of cross-resistance among DMIs reported for some other pathogens and has significant implications with respect to programs for managing grapevine powdery mildew and DMI resistance.

Application of laminarin and calcium oxide for the control of grape powdery mildew on Vitis vinifera cv. Moscato

2018 ◽  
Vol 125 (5) ◽  
pp. 477-482 ◽  
Author(s):  
Massimo Pugliese ◽  
Matteo Monchiero ◽  
Maria Lodovica Gullino ◽  
Angelo Garibaldi
Keyword(s):  
Powdery Mildew ◽  
Vitis Vinifera ◽  
Calcium Oxide ◽  
Cv Moscato ◽  
Grape Powdery Mildew

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.

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