Karel Černý

• Ph.D.
• Head of Department at Landscape Research Institute

Non-native pests, climate change, and their interactions are likely to alter relationships between trees and tree-associated organisms with consequences for forest health. To understand and predict such changes, factors structuring tree-associated communities need to be determined. Here, we analysed the data consisting of records of insects and fun...

Non-native pests, climate change, and their interactions are likely to alter relationships between trees and tree-associated organisms with consequences for forest health. To understand and predict such changes, factors structuring tree-associated communities need to be determined. Here, we analysed the data consisting of records of insects and fun...

In Nov 2011, and then recurrently since Sep 2020, an extensive decline has been recorded in boxwood (Buxus sempervirens), sometimes with several dozens of damaged individuals planted in private gardens and public areas and purchased in amateur markets in the Czech Republic. The leaves of the plants first showed orange-bronze discoloration, then dri...

International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm gene...

International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm gene...

The atlas contains maps for 11 plant pathogens: Colletotrichum salicis (anthracnose and shoot blight of willow), Cryptostroma corticale (sooty bark disease of maple), Dothistroma septosporum (Dothistroma needle blight), Eutypella parasitica (Eutypella canker of maple), Hymenoscyphus fraxineus (ash dieback), Melampsoridium hiratsukanum (alder rust),...

The number of described species of the oomycete genus Phytophthora is growing rapidly, highlighting the need for low-cost, rapid tools for species identification. Here, a collection of 24 Phytophthora species (42 samples) from natural as well as anthropogenic habitats were genetically identified using the internal transcribed spacer (ITS) and cytoc...

In pathogenic fungi and oomycetes, interspecific hybridization may lead to the formation of new species having a greater impact on natural ecosystems than the parental species. From the early 1990s, a severe alder (Alnus spp.) decline due to an unknown Phytophthora species was observed in several European countries. Genetic analyses revealed that t...

A recent outbreak of Phytophthora diseases in fruit orchards was identified in the Czech Republic. The diseased trees showed characteristic symptoms including yellowing, wilting and sparse foliage, decreased yields, root and collar rot, and withering and dying of trees. In some orchards up to 10-15, and rarely up to 55%, of trees died. In total, 38...

Ash dieback, caused by the ascomycete fungus Hymenoscyphus fraxineus, has been rapidly expanding across Europe during the last two decades, posing a considerable threat to native ash populations. In this study, we applied regression-based models trained by field data, in conjunction with geographic information systems, to produce spatial prediction...

Nová kombinace je navržena pro druh Zythia nepenthis, opakovaně zaznamenaný na různých rostlinách rodu Nepenthes ve skleníku v Praze a úspěšně izolovaný jak z hniloby stonku, tak z konidiálních kupek. Fenotypická data spolu s vazbou na Nepenthes jsou v souladu s popisem druhu Z. nepenthis. Na základě sekvencí ITS rDNA a genu pro β-tubulin byl tento...

A new combination is provided for Zythia nepenthis, a fungus repeatedly recorded on various Nepenthes plants in a greenhouse in Prague and successfully isolated from stem rot and conidial ten-drils. Phenotypic data including host specificity matches the description of Z. nepenthis. Based on sequences of ITS rDNA and the gene for b-tubulin, this spe...

Extensive investigation of the impact of ash dieback in forest stands in the Czech Republic was conducted in 2013. Data on the defoliation of ash trees were collected from 1169 forest stands within the entire area of the Czech Republic. A set of 37 variables acquired from different databases (State Forests, GIS, Digital Terrain Model) describing si...

The population of European ash (Fraxinus excelsior) in Europe is severely affected by ash dieback disease caused by Hymen-oscyphus fraxineus. Endophytic fungi are known to influence tree fitness and there are efforts to use them directly or indirectly in the biological control of tree pathogens. To assess possible variation in the fungal community...

Sooty bark disease (SBD) caused by the pathogen Cryptostroma corticale is currently one of the risks to the population of Acer pseudoplatanus in Europe. After a number of records of symptomatic and dead trees in Prague, assessment of the latent non-symptomatic stage of SBD was questioned as a means to forecast the health risk of the A. pseudoplatan...

In 2015 and 2016, the North American maple tree pathogen Eutypella parasitica was identified in Bohemian and Polish Silesia. To date, the pathogen has been recorded in 35 locations over an area of approximately 400 km2. It has been found primarily in natural stands in Silesia in several types of ravine and alluvial forests, in other natural or comm...

Twenty-six commercial formulations of fungicides at six concentrations were evaluated in vitro for their efficacy on mycelial growth of Hymenoscyphus fraxineus (anamorph Chalara fraxinea). The results are presented as EC50, EC90 and minimal inhibitory concentration values; the comparisons with the recommended application concentrations showed that...

The impact of ash dieback caused by Hymenoscyphus fraxineus on 17 provenances of Fraxinus excelsior and one provenance of Fraxinus angustifolia was studied in an extensive field trial established in the Czech Republic prior to the H. fraxineus invasion in 1999. A difference in the level of resistance to ash dieback between the species was found: F....

Phytophthora alni is an invasive organism that causes root and collar rot in alders, which significantly damages the forest and riparian vegetation of alder trees in Central and Western Europe. In the Czech Republic, this pathogen was first confirmed in 2001, and since then it has been gradually spreading from the west to the east. Here, we applied...

The impact of ash dieback caused by Hymenoscyphus fraxineus on 17 provenances of Fraxinus excelsior and one provenance of Fraxinus angustifolia was studied in an extensive field trial established in the Czech Republic prior to the H. fraxineus invasion in 1999. A difference in the level of resistance to ash dieback between the species was found: F....

Due to its high tolerance to acid rain, the North American Colorado blue spruce (Picea pungens) has been among the most frequent substitute tree species used in reforestation programs in spruce mountain forests in the Ore and Sudeten Mts. in the Czech Republic after destruction by sulfur dioxide pollution in the second half of the last century. Thi...

Variation in natural susceptibility of the black alder population to Phytophthora xalni (PA), the oomycete pathogen causing a devastating disease of alder, and its possible relationship to geographic origin, was studied in vitro using branch inoculation tests. Ninety black alder genotypes from different regions of the Czech Republic and two isolate...

An extensive research of distribution of phytophthora disease of alders (primarily caused by Phytophthora alni) was carried out in more than 800 forest plantations in the Czech Republic in 2013. The disease was identified in more than 50% of forest alder plantations, the average damage of alder stands was about 10%. The impact of the disease was mo...

From 2010 to 2012, Phytophthora isolates were obtained from brownish diffusion leaf lesions usually up to 2 to 3 cm in diameter of Rhododendron caucasicum ‘Cheer,’ from withered twigs of Rhododendron sp. with blackish elongated lesions up to ~5 cm in length, and from rotten feeder roots of 2-year-old, chlorotic, wilting seedlings of Fagus sylvatica...

The anamorphic fungus Cryptostroma corticale (Xylariaceae) causing sooty bark disease (SBD) of Acer pseudoplatanus has been reported within the past decade in several European countries. In the last decade, severe drought conditions during summer also resulted in an outbreak of SBD in park areas in Prague (Czech Republic). Trees with the typical sy...

In the Czech Republic, Phytophthora alni was first confirmed in 2001 and the pathogen has been quickly spreading and occupying almost the whole area of the country. The pathogen attacks Alnus glutinosa or A. incana to a lesser extent and causes considerable losses of alder trees along hundreds of kilometres of riverbanks. The aim of our work was to...

Beginning in 2006, a survey of two related Phytophthora species, P. multivora and P. plurivora, was performed in the Czech Republic. Both pathogens were distributed throughout a broad range of environments including forest and riparian stands and probably became naturalised in the country. The two species differed in their frequency and elevational...

The aim of the article is the investigation of potential importance of air humidity in ash dieback epidemiology. The investigation linked up to the previous investigation of the disease impact in different types of ash vegetation in the Lusatian Mountains Protected Landscape Area, Czech Republic. The sensors Datalogger Minikin THi (EMS Brno) measur...

The winter survival of the invasive pathogen Phytophthora alni subsp. alni in black alder stems was studied in the bankside alder stand of the Moravská Dyje River in southern Bohemia after two very different winter seasons: cold in 2008/2009, with the average temperature of –1.96°C, and extremely mild in 2006/2007, with the average temperature of 2...

Limits on the survival of P. alni subsp. alni (PAA) due to low temperature can be expected based on previously published laboratory and field studies. This study presents a laboratory experiment to test the influence of low temperature and frost duration on PAA viability. Ten PAA isolates were incubated at different temperatures (–0.1, –2.5,–5.0, –...

Phytophthora alni is responsible for a devastating disease in alder and changes in the environment of riparian and alder carr ecosystems. One of the main approaches to solve this problem is to find naturally resistant genotypes using a series of artificial inoculation experiments, to preserve and use them in programmes for resistance breeding. Howe...

Ornamental nurseries, garden centres, public gardens and urban greenery in the Czech Republic were surveyed in 2006–2009 for the presence of Phytophthora spp. and the diseases they cause on ericaceous plants. Diseased plants such as Rhododendron spp., Pieris floribunda, Vaccinium sp., and Azalea sp. showed various symptoms including leaf spot, shoo...

This study evaluates the effect of the identified pathogenic races E1, E2 and E3 of the leaf rust Melamp-sora larici-populina on some growth traits and biomass yield in the species Populus nigra. A field trial was conducted with 8 clones of P. nigra using fungicide-sprayed and unsprayed treatments in 3 replications of 4 plants. In the course of thr...

Issues concerning Phytophthora diseases in woody plants and Phytophthora diversity were overlooked in the Czech Republic until 2000. The investigation of a number of important problems concerning Phytophthora diseases of woody plants was initiated in the past decade, including problems related to alder decline caused by Phytophthora alni, the ident...

London plane (Platanus hispanica Mill.) is considered as very tolerant to pollution and other stresses and in the Czech Republic it has been unaffected by important pathogens until now. However, in recent years the health status of London plane has been significantly deteriorating. During an 11-year survey it was found out that development of Londo...

Phytophthora decline of riparian alder populations has recently become an important problem in many European countries, including the Czech Republic. The causal agent, Phytophthora alni, has spread quickly in the Czech Republic. Hundreds of kilometres of riparian alder stands, especially in the western part of the country, have been severely affect...

The three experiments relating to the pathogenicity of Phytophthora cactorum to beech and other forest tree species were carried out. The experiments were aimed to confirm pathogenicity of the pathogen, to compare its pathogenicity with the other Phytophthora species isolated from woody plants in the Czech Republic (P. gonapodyides, P. cambivora, P...

From 2006 to 2008, several similar Phytophthora isolates were obtained from roots of mature Quercus robur and other tree species (Acer platanoides, Fraxinus excelsior, Q. rubra, and Tilia cordata) in forests and parks in several areas in the Czech Republic. The trees were characterized by chlorotic and reduced foliage, crown dieback, and reduced ro...

The influences of long-term flooding and Phytophthora alni subsp. alni infection on the growth and de - velopment of 4-year-old Alnus glutinosa (black alder) saplings were investigated. The black alder saplings were divided into four groups and then subjected to combinations of both factors - flooded and inoculated with pathogen, flooded non-inocul...

During 2007 and the spring of 2008, a disease of poplars (Populus spp.) resembling the Dothichiza canker was found in plantations of fast-growing trees in central Bohemia and in southern Moravia where it was more abundant. The yellowish brown-to-brown, round or elongated cankers occurred on damaged shoots and twigs. Tissues directly under the bark...

Sweet chestnut ( Castanea sativa ) is a non-autochthonous but commonly planted ornamental tree in the Czech Republic. However, this species is sensitive to some Phytophthora infections causing socalled ink disease. The disease usually occurs in warmer regions in Europe. In the Czech Republic it had not been detected until the nineties of the 20th c...

During the summer and autumn of 2006, a disease of rhododendron plants (Ericaceae) was found in nurseries and public gardens in several areas of the Czech Republic. Leaves of damaged plants showed dark brown-to-black lesions extending along the mid-rib and commonly spreading to petioles and shoots. The infected shoots turned black and died. The can...