scholarly journals Overwintering form of Erysiphe necator, the causal agent of grapevine powdery mildew in southern Syria

2017 ◽  
Vol 57 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Nujoud Alimad ◽  
Walid Naffaa ◽  
Fawaz Azmeh
Keyword(s):  
Powdery Mildew ◽  
Winter Season ◽  
Causal Agent ◽  
Bud Break ◽  
Erysiphe Necator ◽  
First Report ◽  
Primary Inoculum ◽  
Grapevine Powdery Mildew ◽  
Histopathological Studies ◽  
Grapevine Buds

AbstractThe main aims of this study were to determine the overwintering form and the primary inoculum ofErysiphe necator,the causal agent of grapevine powdery mildew in southern Syria. Eleven vineyards located at five different geographical sites were visited every week from March to November in 2014 and 2015. The results of field and histopathological studies showed thatE. necatorsurvived as mycelium in dormant grapevine buds during the winter season. The first flag shoots were observed shortly after bud break in spring. The number of flag shoots varied greatly according to vineyards, cultivars and years, being present on 27.4 to 61.9% of the grapevines in 2014, and on 5.2 to 40% of the grapevines in 2015. The percentage of flag shoots on the same grapevine also varied according to the year, cultivar and location. It was between 4.3 to 9.4% in 2014, and 2.1 to 3.6% in 2015. The disease was observed only on Balady and Black cultivars. Conidia were released from the second week of May to early September. The first conidia were trapped around mid-May, and the first secondary symptoms were observed on leaves from mid-May to early June according to the site. Chasmothecia were observed on leaves in 45.5% of the studied vineyards. The first observation of chasmothecia on leaves was in July, and their numbers varied greatly between vineyards and years. Chasmothecia were not detected on bark, nor were ascospores trapped at the beginning of the season. These results confirmed that the ascospores did not have any role in the initiation of spring infection. To the best of our knowledge, this is the first report of the overwintering form ofE. necatorin Syria.

scholarly journals Initiation and development of Erysiphe necator chasmothecia and their role in the epidemiology of grapevine powdery mildew in southern Syria

2016 ◽  
Vol 51 (2) ◽  
Author(s):  
Nujoud Alimad ◽  
Walid Naffaa ◽  
Fawaz Azmeh
Keyword(s):  
Powdery Mildew ◽  
Microscopic Examination ◽  
Fungal Disease ◽  
Erysiphe Necator ◽  
Initial Development ◽  
First Report ◽  
Primary Inoculum ◽  
Grapevine Powdery Mildew ◽  
Sudden Reduction

Powdery mildew caused by <em>Erysiphe necator</em> is the most important fungal disease of grapevine in southern Syria. The purpose of this study was to determine the development of chasmothecia and their role as a primary inoculum in spring. Leaves and/or branches were examined by a stereo binocular from July to December 2014 and 2015. The number of chasmothecia was estimated on both surfaces of the leaves, and their viability was estimated by microscopic examination. During 2 years of survey chasmothecia were detected in 45.5% of vineyards. The initial development of chasmothecia on infected leaves was observed in the second half of July. Their numbers increased from July to October, and the sudden reduction at the beginning of November was noted. Chasmothecia were formed on 38.7% of infected leaves, with 12.5%, 18.4%, and 7.5% on the upper, under and on both surfaces of infected leaves respectively. Chasmothecia were more frequent on the leaf under side (0.6 / leaf) than on the leaf upper side (0.4 / leaf), but their occurrence on both sides together was relatively low (0.2 / leaf), and their numbers were highly variable between vineyards and years. Microscopic examination showed that chasmothecia contained 1–5 (usually three) asci with 1–4 (usually three) ascospores in each asci, and 65.6% of chasmothecia were empty. Their viability decreased between December and February, with an average viability of 1.2% and 0.2% in March and April, respectively. Chasmothecia were not detected on bark and ascospores were not trapped at the beginning of the season. These results indicate that the ascospores have no or little role in the initiation of spring infection. To the best of our knowledge, this is the first report of <em>E. necator</em> chasmothecia development and their role in the initiating infection on grapevine in Syria.

scholarly journals Genetic Structure and Aggressiveness of Erysiphe necator Populations during Grapevine Powdery Mildew Epidemics

2008 ◽  
Vol 74 (20) ◽  
pp. 6327-6332 ◽  
Author(s):  
Josselin Montarry ◽  
Philippe Cartolaro ◽  
François Delmotte ◽  
Jérôme Jolivet ◽  
Laetitia Willocquet
Keyword(s):  
Powdery Mildew ◽  
Latency Period ◽  
Growing Season ◽  
Spore Production ◽  
Erysiphe Necator ◽  
Genetic Groups ◽  
Grapevine Powdery Mildew ◽  
Temporal Differentiation ◽  
Group A ◽  
Group B

ABSTRACT Isolates of the causal ascomycete of grapevine powdery mildew, Erysiphe necator, correspond to two genetically differentiated groups (A and B) that coexist on the same host. This coexistence was analyzed by investigating temporal changes in the genetic and phenotypic structures of E. necator populations during three epidemics. Group A was present only at the start of the growing season, whereas group B was present throughout all three epidemics. Group A was less aggressive in terms of germination and infection efficiency but was more aggressive than group B in terms of the latency period, lesion diameter, and spore production. Our results are consistent with a temporal differentiation of niches, preventing recombination, and suggest an association between the disease level and the frequencies of genetic groups.

First Report of Powdery Mildew of Coreopsis Species Caused by Golovinomyces cichoracearum in the Pacific Northwest

2006 ◽  
Vol 7 (1) ◽  
pp. 57
Author(s):  
Dean A. Glawe ◽  
Gary G. Grove ◽  
Mark Nelson
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Causal Agent ◽  
Diagnostic Features ◽  
First Report ◽  
The Pacific ◽  
Powdery Mildew Disease ◽  
Golovinomyces Cichoracearum

In 2005, the authors encountered a previously unreported powdery mildew disease of Coreopsis verticillata L. (whorled tickseed) ‘Zagreb’ and C. auriculata L. (lobed tickseed) ‘Nana’ in central Washington and determined the causal agent to be Golovinomyces cichoracearum (DC.) VP Gelyuta. This report documents the occurrence of G. cichoracearum on Coreopsis species in the Pacific Northwest, and describes diagnostic features of the disease and causal agent. Accepted for publication 2 March 2006. Published 5 April 2006.

First Report of Powdery Mildew on Dipsacus sylvestris Caused by Sphaerotheca dipsacearum in North America

2006 ◽  
Vol 7 (1) ◽  
pp. 54
Author(s):  
Frank M. Dugan ◽  
Dean A. Glawe
Keyword(s):  
North America ◽  
Powdery Mildew ◽  
Causal Agent ◽  
European Species ◽  
First Report ◽  
Dipsacus Sylvestris ◽  
Noxious Weed

Common teasel (Dipsacus sylvestris) is a European species introduced into North America, and is now widely established and regarded as a noxious weed. In October 2005, a powdery mildew was observed on D. sylvestris in two locations in Pullman, Whitman Co., WA. Examination of diseased material confirmed that the causal agent was S. dipsacearum. This report provides the first documentation of S. dipsacearum on D. sylvestris in North America. Accepted for publication 20 April 2006. Published 7 June 2006.

scholarly journals First report of powdery mildew on Cissus rhombifolia caused by Erysiphe necator in the Czech Republic

2012 ◽  
Vol 7 (1) ◽  
pp. 43-45
Author(s):  
Sung-Eun Cho ◽  
Ji-Hyun Park ◽  
Libor Jankovský ◽  
Hyeon-Dong Shin
Keyword(s):  
Czech Republic ◽  
Powdery Mildew ◽  
Erysiphe Necator ◽  
The Czech Republic ◽  
First Report

scholarly journals No Indication of Strict Host Associations in a Widespread Mycoparasite: Grapevine Powdery Mildew (Erysiphe necator) Is Attacked by Phylogenetically Distant Ampelomyces Strains in the Field

2012 ◽  
Vol 102 (7) ◽  
pp. 707-716 ◽  
Author(s):  
Alexandra Pintye ◽  
Zsolt Bereczky ◽  
Gábor M. Kovács ◽  
László G. Nagy ◽  
Xiangming Xu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Environmental Fate ◽  
Phylogenetic Analyses ◽  
Inter Simple Sequence Repeat ◽  
Issr Markers ◽  
Genetic Distances ◽  
Nuclear Ribosomal Dna ◽  
Erysiphe Necator ◽  
Grapevine Powdery Mildew ◽  
Powdery Mildew Fungi

Pycnidial fungi belonging to the genus Ampelomyces are common intracellular mycoparasites of powdery mildews worldwide. Some strains have already been developed as commercial biocontrol agents (BCAs) of Erysiphe necator and other powdery mildew species infecting important crops. One of the basic, and still debated, questions concerning the tritrophic relationships between host plants, powdery mildew fungi, and Ampelomyces mycoparasites is whether Ampelomyces strains isolated from certain species of the Erysiphales are narrowly specialized to their original mycohosts or are generalist mycoparasites of many powdery mildew fungi. This is also important for the use of Ampelomyces strains as BCAs. To understand this relationship, the nuclear ribosomal DNA internal transcribed spacer (ITS) and partial actin gene (act1) sequences of 55 Ampelomyces strains from E. necator were analyzed together with those of 47 strains isolated from other powdery mildew species. These phylogenetic analyses distinguished five major clades and strains from E. necator that were present in all but one clade. This work was supplemented with the selection of nine inter-simple sequence repeat (ISSR) markers for strain-specific identification of Ampelomyces mycoparasites to monitor the environmental fate of strains applied as BCAs. The genetic distances among strains calculated based on ISSR patterns have also highlighted the genetic diversity of Ampelomyces mycoparasites naturally occurring in grapevine powdery mildew. Overall, this work showed that Ampelomyces strains isolated from E. necator are genetically diverse and there is no indication of strict mycohost associations in these strains. However, these results cannot rule out a certain degree of quantitative association between at least some of the Ampelomyces lineages identified in this work and their original mycohosts.

First Report of Powdery Mildew on Caragana arborescens in Minnesota and North Dakota Caused by Microsphaera (Erysiphe) palczewskii

2006 ◽  
Vol 7 (1) ◽  
pp. 59
Author(s):  
Dean A. Glawe ◽  
Robert W. Stack ◽  
James A. Walla
Keyword(s):  
North America ◽  
Powdery Mildew ◽  
North Dakota ◽  
Rocky Mountains ◽  
Causal Agent ◽  
First Report ◽  
Powdery Mildew Disease ◽  
Caragana Arborescens ◽  
First Time

In North Dakota and Minnesota, the authors encountered a powdery mildew disease of Caragana arborescens Lam. (Siberian pea tree) previously unreported from these states. The causal agent was determined to be Microsphaera palczewskii Jacz. This report documents for the first time the presence of M. palczewskii in North America east of the Rocky Mountains and includes information on the morphology, classification, and distribution of this species. Accepted for publication 4 January 2006. Published 17 January 2006.

First Report of Podosphaera alpina f. alpina on Tolmiea menziesii in Washington State and British Columbia

2009 ◽  
Vol 10 (1) ◽  
pp. 42
Author(s):  
Lydia S. Putnicki ◽  
Dean A. Glawe
Keyword(s):  
British Columbia ◽  
Powdery Mildew ◽  
Washington State ◽  
Causal Agent ◽  
Understory Species ◽  
First Report

Tolmiea menziesii (Pursh) Torr. & A. Gray (Saxifragaceae, piggyback plant) is an understory species typically sold as an ornamental houseplant. We recently made several collections of T. menzii in Washington and British Columbia with powdery mildew symptoms and determined the causal agent to be Podosphaera alpina f. alpina (U. Braun) U. Braun & S. Takam. This is the first report of this fungus on T. menziesii in Washington and British Columbia. Accepted for publication 5 June 2009. Published 10 August 2009.

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