Genetic analyses suggest separate introductions of the pine pathogen Lecanosticta acicola into Europe

Lecanosticta acicola is a heterothallic ascomycete that causes brown spot needle blight on native and nonnative Pinus spp. in many regions of the world. In this study we investigated the origin of European L. acicola populations and estimated the level of random mating of the pathogen in affected areas. Part of the elongation factor 1-α gene was sequenced, 11 microsatellite regions were screened, and the mating type idiomorphs were determined for 201 isolates of L. acicola collected from three continents and 17 host species. The isolates from Mexico and Guatemala were unique, highly diverse and could represent cryptic species of Lecanosticta. The isolates from East Asia formed a uniform and discrete group. Two distinct populations were identified in both North America and Europe. Approximate Bayesian computation analyses strongly suggest independent introductions of two populations from North America into Europe. Microsatellite data and mating type distributions indicated random recombination in the populations of North America and Europe. Its intercontinental introduction can most likely be explained as a consequence of the movement of infected plant material. In contrast, the spread of L. acicola within Europe appears to be primarily due to conidial dispersion and probably also ascospore dissemination.The project was supported financially by COST CZ LD12031 (DIAROD), the FPS COST Action FP1102 (DIAROD), Project indicators of trees vitality Reg. No. CZ.1.07/2.3.00/20.0265 co-financed by the European Social Fund and the state budget of the Czech Republic, the Scholarship Foundation of the Republic of Austria (OeAD-GmbH, Austria) for J. Janoušek. The research was supported with funding from the Austrian Science Fund FWF and the European Union Seventh Framework Programme FP7 2007–2013 (KBBE 2009-3) under grant agreement 245268 ISEFOR.http://apsjournals.apsnet.org/loi/phytohj2017Forestry and Agricultural Biotechnology Institute (FABI)Genetic

Country-Level Modeling of Forest Fires in Austria and the Czech Republic: Insights from Open-Source Data

Forest fires are becoming a serious concern in Central European countries such as Austria (AT) and the Czech Republic (CZ). Mapping fire ignition probabilities across countries can be a useful tool for fire risk mitigation. This study was conducted to: (i) evaluate the contribution of the variables obtained from open-source datasets (i.e., MODIS, OpenStreetMap, and WorldClim) for modeling fire ignition probability at the country level; and (ii) investigate how well the Random Forest (RF) method performs from one country to another. The importance of the predictors was evaluated using the Gini impurity method, and RF was evaluated using the ROC-AUC and confusion matrix. The most important variables were the topographic wetness index in the AT model and slope in the CZ model. The AUC values in the validation sets were 0.848 (AT model) and 0.717 (CZ model). When the respective models were applied to the entire dataset, they achieved 82.5% (AT model) and 66.4% (CZ model) accuracy. Cross-comparison revealed that the CZ model may be successfully applied to the AT dataset (AUC = 0.808, Acc = 82.5%), while the AT model showed poor explanatory power when applied to the CZ dataset (AUC = 0.582, Acc = 13.6%). Our study provides insights into the effect of the accuracy and completeness of open-source data on the reliability of national-level forest fire probability assessment

The Protection of Ash Trees Against Ash Dieback by Tree Injections

Ash dieback caused by a non-native pathogenic fungus Hymenoscyphus fraxineus has been decimating populations of European Fraxinus species for over 30 years. Nevertheless, there is still a considerable amount of valuable ashes of this species in European cities and landscapes. Although it has been shown in many studies that the effect of H. fraxineus on adult and senescent trees tends to be rather chronic, the infection by this fungus also causes a substantial decrease in the lifespan of these trees. This research is dealing with the control of ashes using the tree injection technology. It is focused on the development of bark necroses, as this symptom results in the highest damage to a tree. Trees were first inoculated with two different strains of H. fraxineus. Trees with proven positive inoculation were injected with six different fungicides. Subsequently, over the course of nine months, the area of developing bark necroses was measured using image analysis methods. After the field part of the experiment was finished, the extent of the infection by H. fraxineus in tissues was determined and confirmed by PCR. Three out of six tested variants (Tr. 1: 7.1% propiconazole, Tr. 3: 7% propamocarb and 2.7% fosetyl, and Tr. 6: 0.015% sodium selenite) displayed significant deceleration of the growth of bark necroses compared to control. Tr. 3 demonstrated the highest effectiveness with only a very small increment of the necrosis area during the first three months after the injection treatment and a follow-up complete cessation of growth. Reisolations confirmed high mortality of H. fraxineus after this treatment. Hence the presented study can contribute to substantial prolongation of the lifespan of ashes in Europe.Preprin

Occurrence and pathogenicity of Corinectria spp. - an emerging canker disease of Abies sibirica in Central Siberia

During recent years, a new disease of Siberian fir (A. sibirica) emerged in Central Siberia, exhibiting symptoms of stem/branch deformation, cambium necrosis, and dieback of branches and twigs, the causal agent remaining unknown. The aim was to identify agent of the disease and to investigate its pathogenicity to A. sibirica and Norway spruce (Picea abies). Symptomatic tissues of fir were subjected to pure culture isolation of anticipated pathogen(s). Obtained isolates were subjected to molecular identification, phylogenetic analyses, and pathogenicity tests with A. sibirica saplings, and seeds and seedlings of A. sibirica and P. abies. The study demonstrated that, (i) most commonly isolated fungus from canker wounds of A. sibirica exhibited Acremonium-like anamorphs; (ii) phylogeny demonstrated that investigated fungi belong to genus Corinectria, but are genetically well separated from other worldwide known Corinectria spp.; (iii) one species of isolated fungi has the capacity to cause the disease and kill A. sibirica saplings and seedlings, but also seedlings of P. abies. Guidelines for future research were defined in order to generate needed information on species description, its origin and ecology, and estimation of potential risks upon the eventual invasion of the pathogen to new geographic areas, in particular of Europe

Growth Rates of Lymantria dispar Larvae and Quercus robur Seedlings at Elevated CO2 Concentration and Phytophthora plurivora Infection

Interactions between plants, insects and pathogens are complex and not sufficiently understood in the context of climate change. In this study, the impact of a root pathogen on a leaf-eating insect hosted by a tree species at elevated CO2 concentration is reported for the first time. The combined and isolated effects of CO2 and infection by the root pathogen Phytophthora plurivora on English oak (Quercus robur) seedlings were used to assess growth rates of plants and of gypsy moth (Lymantria dispar) larvae. For this purpose, two Q. robur provenances (Belgrade and Sombor) were used. At ambient CO2 concentration, the relative growth rates of larvae consuming leaves of plants infected by P. plurivora was higher than those consuming non-infected plants. However, at elevated CO2 concentration (1000 ppm) higher relative growth rates were detected in the larvae consuming the leaves of non-infected plants. At ambient CO2 concentration, lower growth rates were recorded in L. dispar larvae hosted in Q. robur from Belgrade in comparison to larvae hosted in Q. robur from Sombor. However, at elevated CO2 concentration, similar growth rates irrespective of the provenance were observed. Defoliation by the gypsy moth did not influence the growth of plants while P. plurivora infection significantly reduced tree height in seedlings from Belgrade. The results confirm that a rise of CO2 concentration in the atmosphere modifies the existing interactions between P. plurivora, Q. robur, and L. dispar. Moreover, the influence of the tree provenances on both herbivore and plant performance at elevated CO2 concentrations suggests a potential for increasing forest resilience through breeding

Suitability of Turkey Oak, European Beech, and Hornbeam to Gypsy Moth Feeding

Pest resistance of trees should be taken into account in future forest strategy planning and predicting risks of defoliation. The gypsy moth (GM) (Lymantria dispar L.) is a serious forest pest with outbreaking population dynamics. To estimate defoliation risk of the most widely distributed tree species in Balkan Peninsula and Europe (Turkey oak Quercus cerris L., European beech Fagus sylvatica L. and hornbeam Carpinus betulus L.), we carried out laboratory feeding trials and investigated their acceptability and suitability for GM development. We determined morphological and chemical attributes of these hosts as well as larval host preference, growth and nutritional indices. Preference, growth, and efficiency of food conversion into biomass were ranked in the order: Turkey oak ˃ European beech ˃ hornbeam. Hornbeam was the most avoided and showed the lowest conversion efficiency although, comparing to optimal oak host, its leaves were less tough, contained more water and exhibited similar values of nitrogen (index of protein content) and C/N ratio (index of investment into carbon based plant defense). We suggest that hornbeam and beech leaf chemical profiles should be further studied to reveal specific compounds that impose high metabolic cost to GM larvae. Moreover, additional research are needed to understand how intermediate hosts in natural populations affect GM outbreaks

Biodiverzita a cílový management ohrožených a chráněných druhů organismů v nízkých a středních lesích v soustavě Natura 2000:TARMAG 2000

Cílem projektu je zhodnotit stav biodiverzity populací evropsky významných druhů rostlin a živočichů v biotopech nízkých a středních lesů a lužních lesů v ČR a navrhnout management těchto biotopů v zájmu cílů soustavy Natura 2000. Bude provedena analýza významu lesů výmladkového původu, včetně lesů nízkých, středních a lužních lesů z hlediska biodiverzity a návrh hospodářských postupů v těchto ekosystémech. Cílový management vybraných druhů organismů bude vyjádřen modelem hospodaření v konkrétních ekosystémech. Projekt je členěn na 8 úkolů. Úkoly 1 – 3 shrnují problematiku nízkých a středních lesů z hlediska biodiverzity, jejich současného stavu a významu z pohledu hospodaření v podmínkách střední Evropy. Úkoly 4 – 7 analyticky hodnotí vazby jednotlivých skupin organismů na nízké a střední lesy, hodnotí jejich biodiverzitu a zpracovávají znalosti o biologii, ekologii, rozšíření a ohrožení druhů vybraných pro cílový management a zásad pro aplikaci cílového managementu. Úkol 8 pak syntetizuje získané poznatky v modelech managementu a návrzích pěstebních opatření pro konkrétní nízké a střední lesy. Biogeografické a geobiocenologické rámce zavádění cílového managementu vzácných druhů organismů v lesích výmladkového původu. 2. Zhodnocení stavu a rozšíření biotopů nízkých a středních lesů (včetně lesů lužních) z hlediska ekologické stability a funkcí krajiny a zachování biodiverzity evropsky významných druhů rostlin a živočichů v soustavě Natura 2000. 3. Historický vývoj a zhodnocení významnosti hospodářských postupů obhospodařujících nízké a střední lesy. 4. - 7. Biodiverzita a cílový management biotopů středních a nízkých lesů z hlediska ochrany vybraných druhů rostlin, hub, hmyzu a obratlovců včetně studia jejich biologie, ekologie a rozšíření. 8. Model managementu biotopů středních a nízkých lesů z hlediska soustavy Natura 2000 a návrh pěstebních opatření a metodika převodů vysokého lesa na nízký a střední včetně ekonomických souvislostí z hlediska vlastníky lesa

Antifeeding, Toxic, and Growth-Reducing Activity of <i>trans</i>-Anethole and <i>S</i>-(+)-Carvone against Larvae of the Gypsy Moth <i>Lymantria dispar</i> (L.)

Botanicals, such as essential oils (EO) and their compounds, are considered a viable eco-friendly alternative to synthetic insecticides, which threaten human health and ecosystem functioning. In the present study, we explored the potential use of two EO compounds, trans-anethole (phenylpropanoid) and S-(+)-carvone (monoterpene ketone), against gypsy moth larvae (GML), a serious pest of deciduous forests and orchards. GML feeding, survival, molting, and nutritional physiology were assessed at different compound concentrations and compared with the effects of the commercial botanical product NeemAzal®-T/S (neem). The impact of botanicals on GML feeding was assessed by the leaf-dipping method and showed the highest antifeeding activity of neem in the no-choice assay. GML that were offered a choice were deterred by anethole and attracted by low concentrations of carvone and neem. Ingestion of botanicals was more effective in inducing mortality and reducing molting than residual contact exposure. Anethole and carvone were better toxicants but worse growth regulators than neem. Assessing nutritional indices revealed reduced growth, consumption, and food utilization in larvae fed on botanical-supplemented diets. The highest metabolic cost of food processing was recorded in carvone-fed larvae, which exhibited a negative growth rate. The results suggest that anethole and carvone might be used as control agents against GML