scholarly journals Incidence of lettuce downy mildew (Bremia lactucae) and powdery mildew (Golovinomyces cichoracearum) in natural populations of prickly lettuce (Lactuca serriola)

2013 ◽  
Vol 49 (Special Issue) ◽  
pp. S24-S32 ◽  
Author(s):  
B. Mieslerová ◽  
A. Lebeda ◽  
I. Petrželová ◽  
P. Korbelová
Keyword(s):  
Czech Republic ◽  
Powdery Mildew ◽  
Downy Mildew ◽  
Natural Infection ◽  
Bremia Lactucae ◽  
The Czech Republic ◽  
Lettuce Downy Mildew ◽  
Lactuca Serriola ◽  
Golovinomyces Cichoracearum ◽  
Prickly Lettuce

The study was focused on the wild pathosystem Lactuca serriola–lettuce downy mildew (Bremia lactucae) and lettuce powdery mildew (Golovinomyces cichoracearum). Observations were focused mainly on recording natural infection of prickly lettuce (Lactuca serriola) by downy and powdery mildews in the East Bohemia and Moravia (the Czech Republic) in the May–September period of 2007–2011, and on the influence of environmental conditions on disease incidence. Only data for July and August were used for the detailed comparisons of occurrence of both pathogens, because intensity of disease in this period was the highest. Data were linked with the average monthly temperature and rainfall rate in the Czech Republic. G. cichoracearum prefers rather low levels of precipitation and temperatures around 20°C, therefore significantly higher incidence of this pathogen was recorded in August 2007. On the other hand in July 2009 and 2010, when the intensities of precipitation were higher, incidence of Bremia lactucae prevailed. In August 2010 and 2011 incidence of both pathogens were more or less similar at all locations. Our observations showed that climatic conditions influence the incidence and prevalence of both pathogens in weedy growing populations of Lactuca serriola.

scholarly journals The First Report of Downy Mildew Caused by Peronospora belbahrii on Sweet Basil in Greenhouses in the Czech Republic

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1579-1579 ◽  
Author(s):  
I. Šafránková ◽  
L. Holková
Keyword(s):  
Czech Republic ◽  
Downy Mildew ◽  
Width Ratio ◽  
Specific Sequence ◽  
The Czech Republic ◽  
First Report ◽  
Sweet Basil ◽  
Potted Plants ◽  
Length Width ◽  
Necrotic Spots

Sweet basil (Ocimum basilicum L.) is an aromatic plant that is cultivated as a pot plant in greenhouses or in fields in the Czech Republic. The plants are intended for direct consumption or for drying. In April of 2012, the first large chlorotic from the middle necrotic spots occurred gradually on leaves of pot plants O. basilicum cv. Genovese in greenhouses in Central Bohemia. The characteristic gray to brown furry growth of downy mildew appeared on abaxial surfaces of leaves in the place of chlorotic spots within 3 to 4 days. The infested leaves fell off in the late stages of pathogenesis. The infestation gradually manifested itself in ever-younger plants and in July, cotyledons and possibly the first true leaves were already heavily infected and damaged and these plants rapidly died. The plant damage reached 80 to 100%, so it was necessary to stop growing the plants in the greenhouse at the end of July. The causal agent was isolated and identified as Peronospora belbahrii Thines by means of morphological and molecular characters (2,3). Conidiophores were hyaline, straight, monopodial, 280 to 460 μm, branched three to five times, ended with two slightly curved branchlets with a single conidia on each branchled tip. The longer branchlets measured 13 to 24 μm (average 18.2 μm), the shorter one 4 to 15 μm (average 9.7 μm). Conidia were rounded or slightly ovoid, from brownish to dark brownish, measured 22 to 31 × 20 to 28 μm (length/width ratio 1.2). A pathogen-specific sequence was detected with the help of the pathogen ITS rDNA specific primers in symptomatic leaves (1). DNA from plant tissues was isolated using the DNeasy plant Mini Kit (Qiagen, Germany) following the standard protocol. PCR was performed using KAPA2G Robust HotStar kit (Kapa Biosystems, United States) according to the conditions recommended in Belbahri et al. (1). The specific products were visualized by electrophoresis through 1.5% agarose gels. Leaves of 20-day-old potted plants O. basilicum ‘Genovese’ were inoculated by spraying with 5 × 105 conidia/ml of the pathogen. Each pot contained 10 plants. Sterilized distilled water was applied to control plants. Plants were covered with polyethylene bags during the entire incubation period to maintain high humidity, and kept at a temperature of 22 to 24°C. Typical disease symptoms appeared on leaves 5 to 9 days after inoculation. Control plants were symptomless. P. belbahrii was re-isolated from the lesions of inoculated plants, thus fulfilling Koch's postulates. Downy mildew on sweet basil was reported in countries in Africa, Europe, and South and North America (4). To our knowledge, this is the first report of downy mildew on sweet basil in the Czech Republic. References: (1) L. Belbahri et al. Mycol. Res. 109:1276, 2005. (2) Y.-J. Choi et al. Mycol. Res. 113:1340, 2009. (3) M. Thines et al. Mycol. Res. 113:532, 2009. (4) C. A. Wyenandt et al. HortScience 45:1416, 2010.

scholarly journals Evaluation of gooseberry cultivars resistance to the American gooseberry powdery mildew Sphaerotheca mors uvae Schwein and its chemical control

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 583-587
Author(s):  
M. Vaverka ◽  
S. Vaverka
Keyword(s):  
Biological Activity ◽  
Czech Republic ◽  
Powdery Mildew ◽  
Chemical Control ◽  
Biological Effect ◽  
Field Trials ◽  
The Czech Republic ◽  
Biological Efficacy ◽  
Extensive Field ◽  
Susceptibility Evaluation

In the course of 1993–2001 extensive field trials were carried out to evaluate the resistance (susceptibility) level of 34 gooseberry cultivars to the American gooseberry powdery mildew Sphaerotheca mors uvae Schwein. Cultivars originated from the Czech Republic and from other European countries. Each tested cultivar had 7 trees (5–10 years old). Beside the resistance (susceptibility) evaluation, biological efficacy of 9 fungicides using EPPO methods has been checked at the same number of cultivars and at the same number of gooseberry trees. Highly significant differences of resistance or susceptibility were observed among gooseberry varieties. Analogical results (differences in biological activity of fungicides) have been attained in the course of chemical treatment. 18 cultivars has been classified as low resistant, 12 cultivars as moderate resistant and 4 cultivars as high resistant. None of the tested fungicides proved perfect biological efficacy (100% healthy berries). 4 of them proved high biological effect (more than 90% healthy berries), 3 proved low biological activity (less than 75% healthy berries) and 2 proved moderate biological activity (75–90% healthy berries).

scholarly journals Host interactors of effector proteins of the lettuce downy mildew Bremia lactucae obtained by yeast two-hybrid screening

PLoS ONE ◽  
2020 ◽  
Vol 15 (5) ◽  
pp. e0226540 ◽  
Author(s):  
Alexandra J. E. Pelgrom ◽  
Claudia-Nicole Meisrimler ◽  
Joyce Elberse ◽  
Thijs Koorman ◽  
Mike Boxem ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Effector Proteins ◽  
Bremia Lactucae ◽  
Yeast Two Hybrid ◽  
Lettuce Downy Mildew ◽  
Two Hybrid ◽  
Hybrid Screening

scholarly journals Long-lasting changes in the species spectrum of cucurbit powdery mildew in the Czech Republic – influence of air temperature changes or random effect?

2010 ◽  
Vol 45 (Special Issue) ◽  
pp. S41-S47 ◽  
Author(s):  
A. Lebeda ◽  
B. Sedláková ◽  
E. Křístková ◽  
M. Vysoudil
Keyword(s):  
Czech Republic ◽  
Powdery Mildew ◽  
Air Temperature ◽  
Mixed Infection ◽  
Random Effect ◽  
Morphological Characteristics ◽  
Infection Prevalence ◽  
The Czech Republic ◽  
Field Crops ◽  
Influence Spreading

Two ectoparasite powdery mildew species <i>Golovinomyces cichoracearum</i> (<i>Gc</i>) and <i>Podosphaera xanthii</i> (<i>Px</i>) occurring on cucurbits differ, besides other characteristics, by specific ecologic requirements. While <i>Px</i> is common in subtropical and tropical areas and greenhouse crops, <i>Gc</i> occurs more frequently in temperate and cooler areas under field conditions. Their presence on cucurbit field crops (<i>Cucurbita pepo</i>, <i>C. maxima</i>, <i>Cucumis sativus</i>) was monitored in the Czechoslovakia (1979–1980) and in the Czech Republic (1995–2007). Their identification was carried out by microscopic observation of the morphological characteristics of the dry conidia on 1527 leaf samples. Data on air temperature in 1979–2007 were provided by the Czech Hydrometeorological Institute. In 1979–1980 <i>Gc</i> was identified in 86.0% of samples, <i>Px</i> in 14.0% samples, there was no mixed infection; prevalence of <i>Px</i> was recorded in South Slovakia and South Moravia, and on crops under cover. Since 1995 species <i>Px</i> was recorded each year on field crops in different locations of Bohemia and Moravia, usually in mixed infection with <i>Gc</i>. The average year temperature of 8.1°C for period 1992–2007 was higher than corresponding value of 7.4°C in 1979–1983. Similarly, average temperature in vegetation season of 16.2°C in 1992–2007 was higher than corresponding value of 15.7°C in 1979–1983. The higher air temperature can positively influence spreading of <i>Px</i> in the Czech Republic. Climate variability and effect of their changes are discussed in relationship to the geographic distribution and geographic patterns of cucurbit powdery mildews.

scholarly journals Insensitivity to the Fungicide Fosetyl-Aluminum in California Isolates of the Lettuce Downy Mildew Pathogen, Bremia lactucae

Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 502-508 ◽  
Author(s):  
Sarah Brown ◽  
Steven T. Koike ◽  
Oswaldo E. Ochoa ◽  
Frank Laemmlen ◽  
Richard W. Michelmore
Keyword(s):  
Quantitative Analysis ◽  
Downy Mildew ◽  
Mating Type ◽  
Control Measures ◽  
Bremia Lactucae ◽  
Widespread Occurrence ◽  
Lettuce Downy Mildew ◽  
Normal Field ◽  
Growth Room ◽  
Disease Pressure

Lettuce downy mildew, caused by Bremia lactucae, is the most important foliar disease of lettuce in California. In recent years, there were apparent failures of fungicides containing fosetyl-aluminum (Aliette) to control downy mildew in commercial lettuce fields in California. Consequently, we characterized 134 isolates collected over 2 years from throughout the coastal growing areas of California for insensitivity to the fungicides fosetyl-aluminum and maneb, pathotype, and mating type. Tests using seedlings in controlled growth room conditions demonstrated the widespread occurrence of insensitivity to fosetyl-aluminum in California populations of B. lactucae. Fifty percent of the isolates assayed sporulated profusely in the presence of fosetyl-aluminum applied at rates twice the normal field dosage, and an additional 40% showed moderate sporulation at this rate. Fosetyl-aluminum-insensitive isolates were detected from all regions sampled. Insensitivity was also observed in multiple pathotypes. Insensitivity was not complete, however, because quantitative analysis of the number of lesions on older plants revealed that applications of fosetyl-aluminum could reduce the levels of disease by 50%. Therefore, while fosetyl-aluminum may have utility under low disease pressure in the field, other control measures are required to provide control under conditions favorable to the disease.

First record of powdery mildew on Homalocladium platycladum in the Czech Republic

2007 ◽  
Vol 56 (4) ◽  
pp. 722-722 ◽  
Author(s):  
A. Lebeda ◽  
B. Mieslerová ◽  
V. Rybka ◽  
M. Sedlářová ◽  
I. Petrželová
Keyword(s):  
Czech Republic ◽  
Powdery Mildew ◽  
First Record ◽  
The Czech Republic

scholarly journals Severity of powdery mildew on winter barley in the Czech Republic in 1976–2005

2008 ◽  
Vol 43 (No. 3) ◽  
pp. 77-85 ◽  
Author(s):  
A. Dreiseitl
Keyword(s):  
Czech Republic ◽  
Powdery Mildew ◽  
Disease Severity ◽  
Field Trials ◽  
Winter Barley ◽  
Sources Of Resistance ◽  
The Czech Republic ◽  
High Infection ◽  
High Disease Severity ◽  
Important Disease

Results of scoring the reaction to powdery mildew of 240 winter barley varieties that were gradually included in 392 Czech Official Trials conducted at 21 locations were analysed. The reaction of the varieties was determined on the basis of the level of infection by the disease. Therefore, the data can also be used to assess the disease severity in years and at locations. Several characteristics indicative of disease severity were considered, including the disease severity coefficient (= average infection of susceptible varieties in trials with a high disease severity/the proportion of such trials). The value of the coefficient is inversely proportional to disease severity. The highest powdery mildew severity was found in 1976, and the years 1988, 1990 and 2003 were characterised by high infection of the examined varieties. In contrast, the disease was practically absent in 1979 and 1982, and its severity was also low in 1978, 1981, 1985, 1991 and 1998. Very low disease severity was found for the period 1977–1982 when insufficient disease severity was found on average in 78% of the trials and high disease severity in only 6% of the trials. The highest disease severity was found at locations Trutnov, Horažďovice and Chrastava. The analysis of data from a large number of field trials conducted at various locations for a period of 30 years confirmed that powdery mildew is an important disease of winter barley in the Czech Republic. Known genetic sources of resistance and current methods, such as marker assisted selection, enable breeders to solve this problem.

scholarly journals Fabian two-row winter barley

2013 ◽  
Vol 49 (No. 4) ◽  
pp. 175-177
Author(s):  
Z. Nesvadba ◽  
J. Špunar ◽  
M. Kadlíková
Keyword(s):  
Czech Republic ◽  
Powdery Mildew ◽  
Plant Height ◽  
Cold Hardiness ◽  
Medium Density ◽  
The Czech Republic ◽  
Variety Trials ◽  
Growing Conditions ◽  
Moderate Resistance ◽  
Very High

Fabian is a medium-late two-row feedin barley of winter habit developed at Agrotest Fyto, Ltd., Kroměř&iacute;ž, Czech Republic (breeders&rsquo; rights holder) and registered in the Czech Republic in 2011. In the Official Variety Trials it showed high grain yields under intensive growing conditions (104.5%) and medium yields under low input conditions (101.1%). Fabian has the highest cold hardiness of the registered two-row winter barleys and regenerates very well in the spring. Its resistance to powdery mildew is very high (score 8.2 on a 1&ndash;9 scale). It has medium plant height, moderate resistance to lodging and large yellow kernel. The spike is long and of medium density.

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