Temporal disease dynamics and relative importance of sexual and asexual reproduction of grape downy mildew ( Plasmopara viticola ) in an isolated vineyard in the North Georgia Mountains, USA

2020 ◽  
Vol 69 (9) ◽  
pp. 1721-1730
Author(s):  
Cheng‐Fang Hong ◽  
Marin T. Brewer ◽  
Phillip M. Brannen ◽  
Harald Scherm
Keyword(s):  
Downy Mildew ◽  
Asexual Reproduction ◽  
Plasmopara Viticola ◽  
Relative Importance ◽  
Disease Dynamics ◽  
The North ◽  
Sexual And Asexual Reproduction ◽  
Grape Downy Mildew

scholarly journals Evaluation of a Disease Warning System for Downy Mildew of Grapes

Plant Disease ◽  
2000 ◽  
Vol 84 (5) ◽  
pp. 549-554 ◽  
Author(s):  
L. V. Madden ◽  
M. A. Ellis ◽  
N. Lalancette ◽  
G. Hughes ◽  
L. L. Wilson
Keyword(s):  
Linear Model ◽  
Downy Mildew ◽  
Environmental Conditions ◽  
Generalized Linear Model ◽  
Disease Incidence ◽  
Warning System ◽  
Plasmopara Viticola ◽  
Effective Control ◽  
Subsequent Infection ◽  
Grape Downy Mildew

An electronic warning system for grape downy mildew— based on models for the infection of leaves of Vitis lambrusca, production of sporangia by Plasmopara viticola in lesions, and sporangial survival—was tested over 7 years in Ohio. Grapevines were sprayed with metalaxyl plus mancozeb (Ridomil MZ58) when the warning system indicated that environmental conditions were favorable for sporulation and subsequent infection. Over the 7 years, plots were sprayed from one to four times according to the warning system, and from four to 10 times according to the standard calendar-based schedule (depending on the date of the initiation of the experiment). The warning system resulted in yearly reductions of one to six sprays (with median of three sprays). Disease incidence (i.e., proportion of leaves with symptoms) in unsprayed plots at the end of the season ranged from 0 to 86%, with a median of 68%. Incidence generally was very similar for the warning-system and standard-schedule treatments (median of 7% of the leaves with symptoms), and both of these incidence values were significantly lower (P < 0.05) than that found for the unsprayed control, based on a generalized-linear-model analysis. Simplifications of the disease warning system, where sprays were applied based only on the infection or sporulation components of the system, were also effective in controlling the disease, although more fungicide applications sometimes were applied. Effective control of downy mildew, therefore, can be achieved with the use of the warning system with fewer sprays than a with a standard schedule.

scholarly journals Geographic Distribution of Cryptic Species of Plasmopara viticola Causing Downy Mildew on Wild and Cultivated Grape in Eastern North America

2014 ◽  
Vol 104 (7) ◽  
pp. 692-701 ◽  
Author(s):  
Mélanie Rouxel ◽  
Pere Mestre ◽  
Anton Baudoin ◽  
Odile Carisse ◽  
Laurent Delière ◽  
...  
Keyword(s):  
North America ◽  
Cryptic Species ◽  
Downy Mildew ◽  
Geographic Distribution ◽  
Host Species ◽  
Large Scale ◽  
Plasmopara Viticola ◽  
Eastern North America ◽  
Grape Downy Mildew ◽  
Parthenocissus Quinquefolia

The putative center of origin of Plasmopara viticola, the causal agent of grape downy mildew, is eastern North America, where it has been described on several members of the family Vitaceae (e.g., Vitis spp., Parthenocissus spp., and Ampelopsis spp.). We have completed the first large-scale sampling of P. viticola isolates across a range of wild and cultivated host species distributed throughout the above region. Sequencing results of four partial genes indicated the presence of a new P. viticola species on Vitis vulpina in Virginia, adding to the four cryptic species of P. viticola recently recorded. The phylogenetic analysis also indicated that the P. viticola species found on Parthenocissus quinquefolia in North America is identical to Plasmopara muralis in Europe. The geographic distribution and host range of five pathogen species was determined through analysis of the internal transcribed spacer polymorphism of 896 isolates of P. viticola. Among three P. viticola species found on cultivated grape, one was restricted to Vitis interspecific hybrids within the northern part of eastern North America. A second species was recovered from V. vinifera and V. labrusca, and was distributed across most of the sampled region. A third species, although less abundant, was distributed across a larger geographical range, including the southern part of eastern North America. P. viticola clade aestivalis predominated (83% of isolates) in vineyards of the European winegrape V. vinifera within the sampled area, indicating that a single pathogen species may represent the primary threat to the European host species within eastern North America.

scholarly journals First Report of Carboxylic Acid Amide Fungicide Resistance in Plasmopara viticola (Grapevine Downy Mildew) in North America

2018 ◽  
Vol 19 (2) ◽  
pp. 139-139 ◽  
Author(s):  
Xuewen Feng ◽  
Anton Baudoin
Keyword(s):  
North Carolina ◽  
Carboxylic Acid ◽  
North America ◽  
Downy Mildew ◽  
Acid Amide ◽  
Plasmopara Viticola ◽  
Carboxylic Acid Amide ◽  
Grapevine Downy Mildew ◽  
Grape Downy Mildew ◽  
Caa Fungicides

This report documents the first known occurrence in North America of resistance in grape downy mildew (Plasmopara viticola) to the carboxylic acid amide (CAA) fungicides mandipropamid and dimethomorph. These fungicides (FRAC group 40) have been an important component of downy mildew management programs for the past decade. Resistant isolates were obtained at three locations in Virginia and one in North Carolina, at considerable distances from each other. Resistance was documented by bioassay and the presence of the G1105S mutation, which has been associated with CAA resistance of P. viticola in other areas. Further survey is needed to determine the geographic extent of this resistance.

Differences in zoospore germination and host penetration in response to temperature among Western Australian isolates of Plasmopara viticola

2007 ◽  
Vol 58 (7) ◽  
pp. 702 ◽  
Author(s):  
M. G. Williams ◽  
P. A. Magarey ◽  
K. Sivasithamparam
Keyword(s):  
Downy Mildew ◽  
Plasmopara Viticola ◽  
Early Infection ◽  
Diverse Range ◽  
Climate Zones ◽  
Host Penetration ◽  
Different Temperatures ◽  
Grape Downy Mildew ◽  
Response To Temperature ◽  
Western Australian

Plasmopara viticola, causal agent of grape downy mildew, was first detected in Western Australia (WA) in widespread commercial viticulture in the Swan Valley (–31.85 S, 116.02 E) in 1998. It has since been found in all viticultural areas in WA, which extend from the far north (–15.75 S, 128.74 E) to the far south (–35.02 S, 117.80 E) of the state across a diverse range of climate zones. Not all of these zones are considered conducive for the development of grape downy mildew. The early infection behaviour of P. viticola isolates, obtained from climatically different grape-growing locations, was examined under different temperatures of incubation (10, 20, and 30°C). Variation in early infection behaviour was used to discern ecotypes of the pathogen. Ten isolates were obtained from WA and 8 of these responded similarly. Three isolates obtained from the east of Australia and used as comparisons in the study behaved similarly to most of the WA isolates. Zoospore germination and host penetration occurred at 10 and 20°C for all isolates. None of the isolates penetrated the host at 30°C. Only 2 isolates, from WA, germinated at 30°C. The early infection behaviour of most of the P. viticola isolates examined in this study appears to be reasonably analogous, despite the influence of varied local environmental conditions. The capacity of certain isolates to germinate under a wider spectrum of temperatures could be indicative of ecotypic specialisation. Such behaviour could confer advantage for the pathogen in viticultural regions that experience high temperatures throughout the growing season.

scholarly journals Climatic risk of grape downy mildew (Plasmopara viticola) for the State of São Paulo, Brazil

2008 ◽  
Vol 65 (spe) ◽  
pp. 60-64 ◽  
Author(s):  
Emília Hamada ◽  
Raquel Ghini ◽  
Paulo Rossi ◽  
Mário José Pedro Júnior ◽  
Jeferson Lobato Fernandes
Keyword(s):  
Relative Humidity ◽  
Downy Mildew ◽  
Plasmopara Viticola ◽  
Sao Paulo ◽  
The State ◽  
Geographical Information ◽  
Weather Data ◽  
Climatic Data ◽  
São Paulo ◽  
Grape Downy Mildew

Viticulture in Brazil has been growing in importance in recent years. In the State of São Paulo, a significant percentage of the production is basically destined to in natura consumption and, more recently, much effort has been made by institutions to revitalize the viticulture in the State. Among fungal diseases, the downy mildew (Plasmopara viticola) is one of the main diseases affecting this crop in Brazil, with extreme damage effects on its production. The objective of this study was to estimate the incidence of the downy mildew on grape under the climatic conditions of the State of São Paulo, based on a mathematical model and using Geographical Information System - GIS tools. The study considered the months from September to April, a period in which the downy mildew can affect grapevines under development. Mean temperature and relative humidity were the basic weather data entered in the GIS database. Leaf wetness duration was estimated from relative humidity measurements. Climatic data entered in the GIS were used to calculate and produce maps depicting the severity of the grape downy mildew, through the application of a disease model. Three cities were evaluated (Jales, Jundiaí, and São Miguel Arcanjo), since they represent the main vineyard centers in the State. The adopted methodology permitted quantifying the severity of the grape downy mildew not only in spatial terms, identifying the variability among the different regions of the State, but also in temporal terms, along the months, making an adequate distinction of the studied cities.

scholarly journals Absence of Oospores of Downy Mildew of Grape Caused by Plasmopara viticola as the Source of Primary Inoculum in Most Western Australian Vineyards

Plant Disease ◽  
2005 ◽  
Vol 89 (7) ◽  
pp. 777-777 ◽  
Author(s):  
B. X. Killigrew ◽  
K. Sivasithamparam ◽  
E. S. Scott
Keyword(s):  
Downy Mildew ◽  
Secondary Infection ◽  
Plasmopara Viticola ◽  
The State ◽  
Annual Rainfall ◽  
Infected Leaf ◽  
Wine Grape ◽  
Primary Inoculum ◽  
The North ◽  
Plant Pathol

Grapevine downy mildew, caused by the obligate, oomycete pathogen, Plasmopara viticola, was first recorded in Western Australia (W.A.) in 1998 (2) and has subsequently been observed in most viticultural regions of the state. Heterothallism in P. viticola was established by Wong et al. (3), whereby more than one mating type of the pathogen is required for sexual reproduction to occur. Oospores are considered to be the source of primary inoculum for this disease with further, secondary infection being advanced by asexual inoculum. However, recent research in European vineyards suggests that the majority of infection throughout the growing season arises via sexually derived (oosporic) inoculum (1). Since downy mildew is relatively new to W.A., few surveys have been conducted to study populations of the pathogen within the state. It is also noteworthy that the incidence of oospores in Australian vineyards has not been reported. The objective of this research was to assess the occurrence and type of inoculum of P. viticola in W.A. vineyards. A total of 1,266 P. viticola-infected leaf discs (LD) from eight wine-grape (775 LD), five table-grape (450 LD), and seven unknown (41 LD) cultivars grown in 16 vineyards in 10 geographically separate regions of W.A. were collected in the growing seasons of 2001-2003. These regions range from Chittering in the north to Albany in the south and received 700 to 1,200 mm annual rainfall, mostly in winter. Each LD was cleared in 1 M KOH at 60°C for 12 to 24 h and then was assessed for the presence of oospores with light microscopy. Leaves showing “mosaic”-type lesions (older infection) late in the season were collected where possible to ensure colony maturity and an increased likelihood of oospore formation. All LD from all regions were negative for the presence of oospores except for samples from a single vineyard (approximately 1,200 mm annual rainfall), where all 140 LD from six wine-grape cultivars contained oospores. The discovery that oospores were present in only one of 16 sampled vineyards provides a rare opportunity to study gene flow in field populations of the pathogen with time and to determine sources of primary inoculum where overwintering of P. viticola may not involve oospores. References: (1) S. McKirdy et al. Plant Dis. 83:301, 1999. (2) A. Rumbou et al. Eur. J. Plant Pathol. 110:379, 2004. (3) F. P. Wong et al. Plant Pathol. 50:427, 2001.

scholarly journals Marker-assisted pyramiding of resistance loci to grape downy mildew

2018 ◽  
Vol 53 (5) ◽  
pp. 602-610 ◽  
Author(s):  
Luciano Saifert ◽  
Fernando David Sánchez-Mora ◽  
Wilson Taybar Assumpção ◽  
Jean Alberto Zanghelini ◽  
Renan Giacometti ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Genetic Material ◽  
Leaf Disc ◽  
Plasmopara Viticola ◽  
Mean Value ◽  
Phenotypic Analysis ◽  
Resistance Level ◽  
High Throughput Method ◽  
Grape Downy Mildew ◽  
Selection For

Abstract: The objective of this work was to use a marker-assisted selection for pyramiding the resistance loci Rpv1 and Rpv3.1 in grapevine (Vitis vinifera), and to evaluate their conferred resistance against Brazilian downy mildew (Plasmopara viticola) isolates. A progeny of 23 plants, segregating for the two resistance loci, was obtained by the cross between the Gf 2000-305-122 and Gf.Ga-52-42 genotypes. The progeny was genotyped with four microsatellite markers and phenotyped for resistance to P. viticola using a bioassay with leaf discs. Six plants containing the Rpv1 and Rpv3.1 pyramided loci were identified by the molecular analysis. Plants harboring the Rpv1 + Rpv3.1, Rpv3.1, and Rpv1 loci showed 12.8, 30.0, and 33.1 sporangiophores per leaf disc, respectively. Plants with no resistance loci showed a dense sporulation. The phenotypic analysis of the expression of the two pyramided loci was only confirmed for four plants that showed the highest resistance level, i.e., mean value of 1.8 sporangiophores. A high-throughput method for pyramiding the Rpv1 and Rpv3.1 loci was developed, which confirmed the increased resistance to P. viticola. The selected elite genetic material shows a high resistance to downy mildew and elevated enological potential for grapevine breeding in Brazil.

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