Variance in leaf spot susceptibility in chestnut trees of different species and hybrids

Journal of Plant Diseases and Protection - Prior to the first occurrence of chestnut blight in 1976, leaf spot caused by Cylindrosporium castaneae was one of the most important diseases of European...     

The hosts and geographic range of Dothistroma needle blight in Slovakia

The occurrence and distribution of Dothistroma needle blight (DNB) were studied in 2014–2017 around Slovakia. A total of 84 localities, both native and planted, were investigated, and the presence of DNB was confirmed in 73 of them. In all positive locations, symptoms typical of DNB were observed and the Dothistroma species was confirmed using species‐specific primers either from fungal cultures or directly from needles. Both Dothistroma species—D. septosporum and D. pini—were identified. Both species occurred together in 29 locations, only D. septosporum in 42 and only D. pini in two locations. The host range of D. septosporum included 10 pine species and two spruce species. The host range of D. pini comprised the same number of pine hosts but only one spruce species. Five pine hosts, P. aristata, P. coulteri, P. densiflora, P. jeffreyi, P. × schwerinii, and one spruce host P. abies are new hosts species of D. pini. P. densiflora and Picea pungens have earlier been reported to be susceptible for DNB. In this study, D. septosporum was found from both tree species.     

Soil Monitoring System as a Basic Tool for Protection of Soils and Sustainable Land Use in Slovakia

The purpose of soil monitoring system in Slovakia is better to protect the soils with regard to sustainable land use. The main objective is the observation of soil properties concerning the main threats to soil： soil contamination, salinisation and sodification, decline in soil organic matter （SOM）, soil compaction and erosion. Soil monitoring system in Slovakia is consistently running since 1993. Its importance consists of providing the information on changing spatial and temporal variations of soil parameters as well as the evolution of soil quality in topsoil and subsoil. Soil monitoring network in Slovakia is constructed using ecological principles, taking into account all main soil types and subtypes, SOM, climatic regions, emission regions, polluted and non-polluted regions as well as various land use. The results of soil monitoring of 318 sites on agricultural land in Slovakia have been presented. Soil properties are evaluated according to the main threats to soil relating to European Commission recommendation for European soil monitoring performance as follows： soil contamination, soil salinization and sodification, decline in SOM, soil compaction and erosion. The most significant change has been determined in physical properties of soils. The physical degradation was especially manifested in compacted and the eroded soils. About 50% of agricultural land is potentially affected by soil erosion in Slovakia. In addition, decline in SOM and available nutrients indicate the serious facts on evaluation and extension of soil degradation processes during the last period in Slovakia. Obtained measured data and required outputs are reported to Joint Research Centre （JRC） in lspra （Italy） and European Environmental Agency （EEA） in Copenhagen （Denmark）. Finally, soil monitoring system thus becomes a basic tool for protection of soils and sustainable land use as well as for the creation of legislatives not only in Slovakia, but in EU, too.     

Tree Injection in the Management of Horse-Chestnut Leaf Miner. Cameraria ohridella (Lepidoptera: Gracillariidae)

Insect and disease problems often occur suddenly, and frequently represent a crisis that demands immediate attention. There are some problems with tree health care because application of sprays to shade trees in urban areas requires specialized, expensive equipment. Microinjection is a type of trunk injection where small amounts of therapeutic chemicals are introduced directly into a tree without any contact with the environment. We applied microinjection technology by using VIVID^®II (Tree Tech Microinjection Systems, Morriston, FL, USA) insecticide to solve the problem with horse-chestnut leaf miner (Cameraria ohridella Deschka et Dimic) on horse chestnut tree (Aesculus hippocastanum L.) in urban greenery in Slovakia. In 2006 were treated 230 host trees in 12 localities, 337 trees in 15 localities were treated in 2007. Mean efficiency of control measures was above 95%. The presence of insecticide residues were analyzed in pollen. 0.145 mg/kg of residues was detected in pollen one day after treatment. It decreased rapidly 8 days after treatment and 16 days after treatment was not detectable. In spite of these results the treatment after blossom is recommended.     

Predicting heavy metal transfer from soil to plant: potential use of Freundlich‐type functions

Soil‐plant transfer of metals is a nonlinear process. We therefore aimed at evaluating the potential of Freundlich‐type functions (c_Plant = b × c_Soil^a) to predict Cd, Cu, Pb, and Zn concentrations in wheat (Triticum aestivum L.) grain and leaf (c_Plant) from soil concentrations (c_Soil). Wheat plants and soil A horizons, mainly developed from Holocene sediments, were sampled at 54 agricultural sites in Slovakia. Metals were extracted from soils with 0.025 M EDTA at pH 4.6 and concentrated HNO₃/HClO₄ (3:1); plant samples were digested with concentrated HNO₃. Total metal concentrations of soil samples were 0.07—25 mg Cd kg^—1, 9.3—220 mg Cu kg^—1, 14—1827 mg Pb kg^—1, and 34—1454 mg Zn kg^—1. On average, between 20 % (Zn) and 80 % (Cd) of the total concentrations were EDTA‐extractable. The total metal concentrations of grain samples were < 0.01—1.3 mg Cd kg^—1, 1.3—6.6 mg Cu kg^—1, < 0.05—0.30 mg Pb kg^—1, and 8—104 mg Zn kg^—1. The leaves contained up to 3.2 mg Cd kg^—1, 111 mg Cu kg^—1, 4.3 mg Pb kg^—1, and 177 mg Zn kg^—1. Linear regression without data transformation was precluded because of the nonnormal data distribution. The Freundlich‐type function was suitable to predict Cd (grain: r = 0.71, leaf: 0.86 for the log‐transformed data) and Zn concentrations (grain: 0.69, leaf: 0.68) in wheat grain and leaf from the EDTA‐extractable metal concentrations. The prediction of Cu and Pb concentrations in grain (Cu: r = 0.44, Pb: 0.41) was poorer and in leaf only possible for Pb (0.50). We suggest to use the Freundlich‐type function for defining threshold values instead of linear regression because it is more appropriate to simulate the nonlinear uptake processes and because it offers interpretation potential. The results suggest that the coefficient b of the Freundlich‐type function depends on the intensity of metal uptake, while the coefficient a reflects the plants' capability to control the heavy metal uptake. The latter is also sensitive to metal translocation in plants and atmospheric deposition.<?show $6#>     

Characteristics of the Cryphonectria parasitica isolated from Quercus in Slovakia

The occurrence of chestnut blight (Cryphonectria parasitica) on oaks in mixed chestnut‐oak forests was studied in 2003–2008 in Slovakia. Infections on living Quercus trees were found at four of seven localities. The disease incidence on oaks ranged from 1.3% to 15.8%. The symptoms on infected oaks were similar to those on chestnut, but less conspicuous. Cankers of C. parasitica were found only on Quercus robur and Q. petraea. A total of 22 isolates of C. parasitica, all virulent, were isolated. Each site yielded only a single vc type (EU12 or EU13). Field inoculation experiments on chestnuts with seven strains of C. parasitica from oaks and an isolate from Castanea sativa showed no differences in virulence. On Quercus robur stems, the cankered area was significantly smaller than on C. sativa and the cankers developed very slowly.     

Concentrations and forms of heavy metals in Slovak soils

The risk assessment of heavy‐metal contamination in soils requires knowledge of the controls of metal concentrations and speciation. We tested the relationship between soil properties (pH, CEC, C_org, oxide concentrations, texture) and land use (forest, grassland, arable) and the partitioning of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn among the seven fractions of a sequential extraction procedure in 146 A horizons from Slovakia. Using a cluster analysis, we identified 92 soils as representing background metal concentrations while the remaining 54 soils showed anthropogenic contamination. Among the background soils, forest soils had the lowest heavy‐metal concentrations except for Pb (highest), because of the shielding effect of the organic layer. Arable soils had the highest Cr, Cu, and Ni concentrations suggesting metal input with agrochemicals. Grassland soils had the highest Cd and Zn concentrations probably for geogenic reasons. Besides the parent material (highest metal concentrations in soils from carbonatic rock, lowest in quartz‐rich soils with sandy texture), pedogenic eluviation processes controlled metal concentrations with podzols showing depletion of most metals in E horizons. Partitioning among the seven fractions of the sequential extraction procedure was element‐specific. The pH was the overwhelming control of the contributions of the bioavailable fractions (fractions 1–4) of all metals and even influenced the contributions of Fe oxide‐associated metals (fractions 5 and 6) to total metal concentrations. For fractions 5 and 6, Fe concentrations in oxides were the most important control of contributions to total metal concentrations. After statistically separating the pH from land use, we found that the contributions of Cu in fractions 1–4 and of NH₄NO₃‐extractable Al, Cd, Pb, and Zn to total metal concentrations were significantly higher under forest than under grassland and in some cases arable use. Our results confirm that metal speciation in soils is mainly controlled by the pH. Furthermore, land use has a significant effect.     

Community structure of fishes inhabiting aquatic refuges in a threatened Karst wetland and its implications for ecosystem management

We illustrate the importance of subsurface refuges for conservation of aquatic fauna with our studies of karstic wetlands in Everglades National Park, Florida, USA. Managers have proposed that water levels there should not fall more than 46 cm below ground level for more than 90 days annually. In four areas, 84% of solution holes were less than 46 cm deep and holes deeper than 1m were rare (<3 km⁻²). Null-model analysis indicated no “structure” in the solution-hole fish communities early in the dry season, but that structure emerged as drying progressed. Native cyprinodontiforms were abundant in shallow solution holes that dry annually under current management, while predatory species (often non-native) tended to dominate deeper holes. Water quality was correlated with hole volume and with composition of late dry-season fish communities. Tremendous losses of fish biomass occurred when water levels fell below 46 cm from ground surface. Most native taxa were unlikely to survive in the deep refuges that held predatory non-native taxa.