scholarly journals Occurrence of abnormal form of conidia of onion downy mildew [Peronospora destructor (Berkeley) Caspary].

1991 ◽  
Vol 33 (0) ◽  
pp. 73-74
Author(s):  
Takashi TANAKA ◽  
Kazumi IRIE ◽  
Hideyuki UEDA
Keyword(s):  
Downy Mildew ◽  
Peronospora Destructor ◽  
Abnormal Form ◽  
Onion Downy Mildew

Control of onion downy mildew in the presence of phenylamide-resistant strains of Peronospora destructor (Berk.) Caspary

1992 ◽  
Vol 32 (5) ◽  
pp. 669 ◽  
Author(s):  
RG O'Brien
Keyword(s):  
Downy Mildew ◽  
Disease Severity ◽  
Field Trials ◽  
Copper Hydroxide ◽  
Peronospora Destructor ◽  
Phenylamide Fungicides ◽  
Resistant Strains ◽  
Onion Downy Mildew ◽  
Reduce Disease Severity

Two isolates of Peronospora destructor differed in their sensitivities to phenylamide fungicides. An isolate (3014) from the Lockyer Valley did not respond to increasing concentrations of metalaxyl, benalaxyl and oxadixyl between 0.1 and 200 mg a.i./L. An isolate (2967) from Bundaberg was sensitive to these fungicides, with EC50 values (concentrations which reduce disease severity by 50%) of 1.6, 6.0 and 12.1 mg a.i./L, respectively. Isolates 3014 and 2967 were both sensitive to dimethomorph, with EC50 values of 4.3 and 1.4 mg a.i./L, respectively. Field trials compared the efficacy of fungicides for the control of onion downy mildew in the Lockyer Valley in 1989 and 1990. In both trials, treatments containing mancozeb gave the best control, resulting in yield increases of 60% in 1990. There was no difference from the check treatment in either disease severity or yield when metalaxyl was applied, suggesting that phenylamide-resistant strains were prevalent. Other fungicide treatments which did not significantly reduce the severity of downy mildew in the 1990 trial included copper hydroxide, chlorothalonil, fosetyl-Al, and propamocarb. The experimental compound dimethomorph, although less effective than mancozeb, significantly reduced disease severity and increased yield by 24%.

scholarly journals Factors Influencing the Occurrence of Onion Downy Mildew (Peronospora destructor) Epidemics: Trends from 31 Years of Observational Data

Agronomy ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 738 ◽  
Author(s):  
Hervé Van der Heyden ◽  
Pierre Dutilleul ◽  
Jean-Benoît Charron ◽  
Guillaume J. Bilodeau ◽  
Odile Carisse
Keyword(s):  
Downy Mildew ◽  
Observational Data ◽  
Disease Incidence ◽  
Principal Component ◽  
Precipitation Regime ◽  
Peronospora Destructor ◽  
Northern Latitudes ◽  
Regional Basis ◽  
Regional Disease ◽  
Onion Downy Mildew

Onion downy mildew (ODM) caused by Peronospora destructor has been increasing annually in south-western Québec since the early 2000s, reaching 33% of affected onion fields in 2014. Using observational data collected over a period of 31 consecutive years, this study aimed to investigate the variations in ODM incidence and epidemic onset and identify the meteorological variables that influence its polyetic development. A logistic model was fitted to each ODM epidemic to estimate and compare the onset of epidemics on a regional basis. Results of this analysis showed that the first observation date, 10% epidemic onset (b10) and mid-time (b) were, on average, 30.4, 15.1 and 11.3 days earlier in 2007–2017 than in 1987–1996. Results of a principal component analysis suggested that regional disease incidence was mostly influenced by the precipitation regime, the final regional disease incidence the previous year, and warmer temperature during the harvest period the previous fall. Subsequently, the data were divided in three periods of 10, 10 and 11 years, and a discriminant analysis was performed to classify each year in the correct period. Using a sufficient subset of five discriminating variables (temperature and rainfall at harvest the previous fall, winter coldness, solar radiation, and disease incidence the previous year), it was possible to classify 93.5% of the ODM epidemics in the period where they belong. These results suggest that P. destructor may overwinter under northern latitudes and help to highlight the need for more research on overwintering and for the development of molecular-based tools enabling the monitoring of initial and secondary inoculum.

An Epidemic of Downy Mildew caused by Peronospora destructor on Vidalia Sweet Onions in Georgia in 2012

2013 ◽  
Vol 14 (1) ◽  
pp. 54
Author(s):  
Venkatesan Parkunan ◽  
Ronald D. Gitaitis ◽  
Bhabesh Dutta ◽  
David B. Langston ◽  
Pingsheng Ji
Keyword(s):  
Downy Mildew ◽  
Peronospora Destructor ◽  
Recent Outbreak ◽  
The Impact ◽  
Onion Downy Mildew

The first reported occurrence of onion downy mildew (ODM) on Vidalia sweet onions in Georgia was in 1999. Although the disease is not common every year, two epidemics have occurred since 1999. The authors report here on the impact of a recent outbreak of ODM on the $100-million Vidalia onion crop in 2012. Accepted for publication 29 January 2013. Published 28 March 2013.

Peronospora destructor. [Descriptions of Fungi and Bacteria].

1975 ◽  
Author(s):  
K. G. Mukerji
Keyword(s):  
South Africa ◽  
New Zealand ◽  
East Asia ◽  
Downy Mildew ◽  
Geographical Distribution ◽  
Wild Species ◽  
Peronospora Destructor ◽  
North East

Abstract A description is provided for Peronospora destructor. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Affects species of Allium; common on A. cepa, rarer on A. ascalonicum, A. fistulosum, A. porrum, A. sativum, A. schoenoprasum, and a few wild species. DISEASE: Downy mildew (mildiou, falscher Mehitau) of onion. GEOGRAPHICAL DISTRIBUTION: On onion in all parts of Europe and America; north, east and south Africa, west, south and east Asia, Australia, New Zealand; and Tasmania. On other Allium crops in a few countries in Europe and on other continents (CMI Map 76. ed. 3, 1969).

scholarly journals High-Quality Genome Assembly of Peronospora destructor, the Causal Agent of Onion Downy Mildew

2020 ◽  
Vol 33 (5) ◽  
pp. 718-720
Author(s):  
Karthi Natesan ◽  
Ji Yeon Park ◽  
Cheol-Woo Kim ◽  
Dong Suk Park ◽  
Young-Seok Kwon ◽  
...  
Keyword(s):  
Downy Mildew ◽  
De Novo ◽  
Gc Content ◽  
Comparative Genomic ◽  
High Quality ◽  
Sequencing Platform ◽  
Peronospora Destructor ◽  
Genomic Studies ◽  
Genome Assemblies ◽  
High Quality Genome

Peronospora destructor is an obligate biotrophic oomycete that causes downy mildew on onion (Allium cepa). Onion is an important crop worldwide, but its production is affected by this pathogen. We sequenced the genome of P. destructor using the PacBio sequencing platform, and de novo assembly resulted in 74 contigs with a total contig size of 29.3 Mb and 48.48% GC content. Here, we report the first high-quality genome sequence of P. destructor and its comparison with the genome assemblies of other oomycetes. The genome is a very useful resource to serve as a reference for analysis of P. destructor isolates and for comparative genomic studies of the biotrophic oomycetes.

scholarly journals The Power of Genomic in situ Hybridization (GISH) in Interspecific Breeding of Bulb Onion (Allium cepa L.) Resistant to Downy Mildew (Peronospora destructor [Berk.] Casp.)

Plants ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 36 ◽  
Author(s):  
Ludmila Khrustaleva ◽  
Majd Mardini ◽  
Natalia Kudryavtseva ◽  
Rada Alizhanova ◽  
Dmitry Romanov ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Downy Mildew ◽  
Allium Cepa ◽  
Genomic In Situ Hybridization ◽  
Lethal Gene ◽  
Peronospora Destructor ◽  
Bulb Onion ◽  
Allium Cepa L ◽  
Interspecific Breeding

We exploited the advantages of genomic in situ hybridization (GISH) to monitor the introgression process at the chromosome level using a simple and robust molecular marker in the interspecific breeding of bulb onion (Allium cepa L.) that is resistant to downy mildew. Downy mildew (Peronospora destructor [Berk.] Casp.) is the most destructive fungal disease for bulb onions. With the application of genomic in situ hybridization (GISH) and previously developed DMR1 marker, homozygous introgression lines that are resistant to downy mildew were successfully produced in a rather short breeding time. Considering that the bulb onion is a biennial plant, it took seven years from the F1 hybrid production to the creation of S2BC2 homozygous lines that are resistant to downy mildew. Using GISH, it was shown that three progeny plants of S2BC2 possessed an A. roylei homozygous fragment in the distal region of the long arm of chromosomes 3 in an A. cepa genetic background. Previously, it was hypothesized that a lethal gene(s) was linked to the downy mildew resistance gene. With the molecular cytogenetic approach, we physically mapped more precisely the lethal gene(s) using the homozygous introgression lines that differed in the size of the A. roylei fragments on chromosome 3.

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